diff --git a/modules/templates/helper.go b/modules/templates/helper.go
index 40a79d9578..f93419fe87 100644
--- a/modules/templates/helper.go
+++ b/modules/templates/helper.go
@@ -138,7 +138,7 @@ func NewFuncMap() []template.FuncMap {
 		"TimeSinceUnix": timeutil.TimeSinceUnix,
 		"Sec2Time":      util.SecToTime,
 		"DateFmtLong": func(t time.Time) string {
-			return t.Format(time.RFC1123Z)
+			return t.Format(time.RFC3339)
 		},
 		"LoadTimes": func(startTime time.Time) string {
 			return fmt.Sprint(time.Since(startTime).Nanoseconds()/1e6) + "ms"
diff --git a/modules/timeutil/since.go b/modules/timeutil/since.go
index daa5e15419..bdde54c617 100644
--- a/modules/timeutil/since.go
+++ b/modules/timeutil/since.go
@@ -6,11 +6,9 @@ package timeutil
 import (
 	"fmt"
 	"html/template"
-	"math"
 	"strings"
 	"time"
 
-	"code.gitea.io/gitea/modules/setting"
 	"code.gitea.io/gitea/modules/translation"
 )
 
@@ -24,10 +22,6 @@ const (
 	Year   = 12 * Month
 )
 
-func round(s float64) int64 {
-	return int64(math.Round(s))
-}
-
 func computeTimeDiffFloor(diff int64, lang translation.Locale) (int64, string) {
 	diffStr := ""
 	switch {
@@ -86,94 +80,6 @@ func computeTimeDiffFloor(diff int64, lang translation.Locale) (int64, string) {
 	return diff, diffStr
 }
 
-func computeTimeDiff(diff int64, lang translation.Locale) (int64, string) {
-	diffStr := ""
-	switch {
-	case diff <= 0:
-		diff = 0
-		diffStr = lang.Tr("tool.now")
-	case diff < 2:
-		diff = 0
-		diffStr = lang.Tr("tool.1s")
-	case diff < 1*Minute:
-		diffStr = lang.Tr("tool.seconds", diff)
-		diff = 0
-
-	case diff < Minute+Minute/2:
-		diff -= 1 * Minute
-		diffStr = lang.Tr("tool.1m")
-	case diff < 1*Hour:
-		minutes := round(float64(diff) / Minute)
-		if minutes > 1 {
-			diffStr = lang.Tr("tool.minutes", minutes)
-		} else {
-			diffStr = lang.Tr("tool.1m")
-		}
-		diff -= diff / Minute * Minute
-
-	case diff < Hour+Hour/2:
-		diff -= 1 * Hour
-		diffStr = lang.Tr("tool.1h")
-	case diff < 1*Day:
-		hours := round(float64(diff) / Hour)
-		if hours > 1 {
-			diffStr = lang.Tr("tool.hours", hours)
-		} else {
-			diffStr = lang.Tr("tool.1h")
-		}
-		diff -= diff / Hour * Hour
-
-	case diff < Day+Day/2:
-		diff -= 1 * Day
-		diffStr = lang.Tr("tool.1d")
-	case diff < 1*Week:
-		days := round(float64(diff) / Day)
-		if days > 1 {
-			diffStr = lang.Tr("tool.days", days)
-		} else {
-			diffStr = lang.Tr("tool.1d")
-		}
-		diff -= diff / Day * Day
-
-	case diff < Week+Week/2:
-		diff -= 1 * Week
-		diffStr = lang.Tr("tool.1w")
-	case diff < 1*Month:
-		weeks := round(float64(diff) / Week)
-		if weeks > 1 {
-			diffStr = lang.Tr("tool.weeks", weeks)
-		} else {
-			diffStr = lang.Tr("tool.1w")
-		}
-		diff -= diff / Week * Week
-
-	case diff < 1*Month+Month/2:
-		diff -= 1 * Month
-		diffStr = lang.Tr("tool.1mon")
-	case diff < 1*Year:
-		months := round(float64(diff) / Month)
-		if months > 1 {
-			diffStr = lang.Tr("tool.months", months)
-		} else {
-			diffStr = lang.Tr("tool.1mon")
-		}
-		diff -= diff / Month * Month
-
-	case diff < Year+Year/2:
-		diff -= 1 * Year
-		diffStr = lang.Tr("tool.1y")
-	default:
-		years := round(float64(diff) / Year)
-		if years > 1 {
-			diffStr = lang.Tr("tool.years", years)
-		} else {
-			diffStr = lang.Tr("tool.1y")
-		}
-		diff -= (diff / Year) * Year
-	}
-	return diff, diffStr
-}
-
 // MinutesToFriendly returns a user friendly string with number of minutes
 // converted to hours and minutes.
 func MinutesToFriendly(minutes int, lang translation.Locale) string {
@@ -208,43 +114,14 @@ func timeSincePro(then, now time.Time, lang translation.Locale) string {
 	return strings.TrimPrefix(timeStr, ", ")
 }
 
-func timeSince(then, now time.Time, lang translation.Locale) string {
-	return timeSinceUnix(then.Unix(), now.Unix(), lang)
-}
-
-func timeSinceUnix(then, now int64, lang translation.Locale) string {
-	lbl := "tool.ago"
-	diff := now - then
-	if then > now {
-		lbl = "tool.from_now"
-		diff = then - now
-	}
-	if diff <= 0 {
-		return lang.Tr("tool.now")
-	}
-
-	_, diffStr := computeTimeDiff(diff, lang)
-	return lang.Tr(lbl, diffStr)
-}
-
-// TimeSince calculates the time interval and generate user-friendly string.
+// TimeSince renders relative time HTML given a time.Time
 func TimeSince(then time.Time, lang translation.Locale) template.HTML {
-	return htmlTimeSince(then, time.Now(), lang)
+	timestamp := then.UTC().Format(time.RFC3339)
+	// declare data-tooltip-content attribute to switch from "title" tooltip to "tippy" tooltip
+	return template.HTML(fmt.Sprintf(`<relative-time class="time-since" prefix="%s" datetime="%s" data-tooltip-content data-tooltip-interactive="true">%s</relative-time>`, lang.Tr("on_date"), timestamp, timestamp))
 }
 
-func htmlTimeSince(then, now time.Time, lang translation.Locale) template.HTML {
-	return template.HTML(fmt.Sprintf(`<span class="time-since" data-tooltip-content="%s" data-tooltip-interactive="true">%s</span>`,
-		then.In(setting.DefaultUILocation).Format(GetTimeFormat(lang.Language())),
-		timeSince(then, now, lang)))
-}
-
-// TimeSinceUnix calculates the time interval and generate user-friendly string.
+// TimeSinceUnix renders relative time HTML given a TimeStamp
 func TimeSinceUnix(then TimeStamp, lang translation.Locale) template.HTML {
-	return htmlTimeSinceUnix(then, TimeStamp(time.Now().Unix()), lang)
-}
-
-func htmlTimeSinceUnix(then, now TimeStamp, lang translation.Locale) template.HTML {
-	return template.HTML(fmt.Sprintf(`<span class="time-since" data-tooltip-content="%s" data-tooltip-interactive="true">%s</span>`,
-		then.FormatInLocation(GetTimeFormat(lang.Language()), setting.DefaultUILocation),
-		timeSinceUnix(int64(then), int64(now), lang)))
+	return TimeSince(then.AsLocalTime(), lang)
 }
diff --git a/modules/timeutil/since_test.go b/modules/timeutil/since_test.go
index 9a037c7bd0..40fefe8700 100644
--- a/modules/timeutil/since_test.go
+++ b/modules/timeutil/since_test.go
@@ -5,7 +5,6 @@ package timeutil
 
 import (
 	"context"
-	"fmt"
 	"os"
 	"testing"
 	"time"
@@ -40,46 +39,6 @@ func TestMain(m *testing.M) {
 	os.Exit(retVal)
 }
 
-func TestTimeSince(t *testing.T) {
-	assert.Equal(t, "now", timeSince(BaseDate, BaseDate, translation.NewLocale("en-US")))
-
-	// test that each diff in `diffs` yields the expected string
-	test := func(expected string, diffs ...time.Duration) {
-		t.Run(expected, func(t *testing.T) {
-			for _, diff := range diffs {
-				actual := timeSince(BaseDate, BaseDate.Add(diff), translation.NewLocale("en-US"))
-				assert.Equal(t, translation.NewLocale("en-US").Tr("tool.ago", expected), actual)
-				actual = timeSince(BaseDate.Add(diff), BaseDate, translation.NewLocale("en-US"))
-				assert.Equal(t, translation.NewLocale("en-US").Tr("tool.from_now", expected), actual)
-			}
-		})
-	}
-	test("1 second", time.Second, time.Second+50*time.Millisecond)
-	test("2 seconds", 2*time.Second, 2*time.Second+50*time.Millisecond)
-	test("1 minute", time.Minute, time.Minute+29*time.Second)
-	test("2 minutes", 2*time.Minute, time.Minute+30*time.Second)
-	test("2 minutes", 2*time.Minute, 2*time.Minute+29*time.Second)
-	test("1 hour", time.Hour, time.Hour+29*time.Minute)
-	test("2 hours", 2*time.Hour, time.Hour+30*time.Minute)
-	test("2 hours", 2*time.Hour, 2*time.Hour+29*time.Minute)
-	test("3 hours", 3*time.Hour, 2*time.Hour+30*time.Minute)
-	test("1 day", DayDur, DayDur+11*time.Hour)
-	test("2 days", 2*DayDur, DayDur+12*time.Hour)
-	test("2 days", 2*DayDur, 2*DayDur+11*time.Hour)
-	test("3 days", 3*DayDur, 2*DayDur+12*time.Hour)
-	test("1 week", WeekDur, WeekDur+3*DayDur)
-	test("2 weeks", 2*WeekDur, WeekDur+4*DayDur)
-	test("2 weeks", 2*WeekDur, 2*WeekDur+3*DayDur)
-	test("3 weeks", 3*WeekDur, 2*WeekDur+4*DayDur)
-	test("1 month", MonthDur, MonthDur+14*DayDur)
-	test("2 months", 2*MonthDur, MonthDur+15*DayDur)
-	test("2 months", 2*MonthDur, 2*MonthDur+14*DayDur)
-	test("1 year", YearDur, YearDur+5*MonthDur)
-	test("2 years", 2*YearDur, YearDur+6*MonthDur)
-	test("2 years", 2*YearDur, 2*YearDur+5*MonthDur)
-	test("3 years", 3*YearDur, 2*YearDur+6*MonthDur)
-}
-
 func TestTimeSincePro(t *testing.T) {
 	assert.Equal(t, "now", timeSincePro(BaseDate, BaseDate, translation.NewLocale("en-US")))
 
@@ -113,60 +72,6 @@ func TestTimeSincePro(t *testing.T) {
 			12*time.Minute+17*time.Second)
 }
 
-func TestHtmlTimeSince(t *testing.T) {
-	setting.TimeFormat = time.UnixDate
-	setting.DefaultUILocation = time.UTC
-	// test that `diff` yields a result containing `expected`
-	test := func(expected string, diff time.Duration) {
-		actual := htmlTimeSince(BaseDate, BaseDate.Add(diff), translation.NewLocale("en-US"))
-		assert.Contains(t, actual, `data-tooltip-content="Sat Jan  1 00:00:00 UTC 2000"`)
-		assert.Contains(t, actual, expected)
-	}
-	test("1 second", time.Second)
-	test("3 minutes", 3*time.Minute+5*time.Second)
-	test("1 day", DayDur+11*time.Hour)
-	test("1 week", WeekDur+3*DayDur)
-	test("3 months", 3*MonthDur+2*WeekDur)
-	test("2 years", 2*YearDur)
-	test("3 years", 2*YearDur+11*MonthDur+4*WeekDur)
-}
-
-func TestComputeTimeDiff(t *testing.T) {
-	// test that for each offset in offsets,
-	// computeTimeDiff(base + offset) == (offset, str)
-	test := func(base int64, str string, offsets ...int64) {
-		for _, offset := range offsets {
-			t.Run(fmt.Sprintf("%s:%d", str, offset), func(t *testing.T) {
-				diff, diffStr := computeTimeDiff(base+offset, translation.NewLocale("en-US"))
-				assert.Equal(t, offset, diff)
-				assert.Equal(t, str, diffStr)
-			})
-		}
-	}
-	test(0, "now", 0)
-	test(1, "1 second", 0)
-	test(2, "2 seconds", 0)
-	test(Minute, "1 minute", 0, 1, 29)
-	test(Minute, "2 minutes", 30, Minute-1)
-	test(2*Minute, "2 minutes", 0, 29)
-	test(2*Minute, "3 minutes", 30, Minute-1)
-	test(Hour, "1 hour", 0, 1, 29*Minute)
-	test(Hour, "2 hours", 30*Minute, Hour-1)
-	test(5*Hour, "5 hours", 0, 29*Minute)
-	test(Day, "1 day", 0, 1, 11*Hour)
-	test(Day, "2 days", 12*Hour, Day-1)
-	test(5*Day, "5 days", 0, 11*Hour)
-	test(Week, "1 week", 0, 1, 3*Day)
-	test(Week, "2 weeks", 4*Day, Week-1)
-	test(3*Week, "3 weeks", 0, 3*Day)
-	test(Month, "1 month", 0, 1)
-	test(Month, "2 months", 16*Day, Month-1)
-	test(10*Month, "10 months", 0, 13*Day)
-	test(Year, "1 year", 0, 179*Day)
-	test(Year, "2 years", 180*Day, Year-1)
-	test(3*Year, "3 years", 0, 179*Day)
-}
-
 func TestMinutesToFriendly(t *testing.T) {
 	// test that a number of minutes yields the expected string
 	test := func(expected string, minutes int) {
diff --git a/modules/timeutil/timestamp.go b/modules/timeutil/timestamp.go
index c8e0d4bdc1..c60d287fae 100644
--- a/modules/timeutil/timestamp.go
+++ b/modules/timeutil/timestamp.go
@@ -64,9 +64,8 @@ func (ts TimeStamp) AsLocalTime() time.Time {
 }
 
 // AsTimeInLocation convert timestamp as time.Time in Local locale
-func (ts TimeStamp) AsTimeInLocation(loc *time.Location) (tm time.Time) {
-	tm = time.Unix(int64(ts), 0).In(loc)
-	return tm
+func (ts TimeStamp) AsTimeInLocation(loc *time.Location) time.Time {
+	return time.Unix(int64(ts), 0).In(loc)
 }
 
 // AsTimePtr convert timestamp as *time.Time in Local locale
diff --git a/options/locale/locale_en-US.ini b/options/locale/locale_en-US.ini
index bd7e64fc6d..08b23e0387 100644
--- a/options/locale/locale_en-US.ini
+++ b/options/locale/locale_en-US.ini
@@ -112,6 +112,8 @@ never = Never
 
 rss_feed = RSS Feed
 
+on_date = on
+
 [aria]
 navbar = Navigation Bar
 footer = Footer
@@ -3191,7 +3193,6 @@ details.documentation_site = Documentation Site
 details.license = License
 assets = Assets
 versions = Versions
-versions.on = on
 versions.view_all = View all
 dependency.id = ID
 dependency.version = Version
diff --git a/package-lock.json b/package-lock.json
index 3d565d7864..e857bc137c 100644
--- a/package-lock.json
+++ b/package-lock.json
@@ -13,6 +13,7 @@
         "@citation-js/plugin-software-formats": "0.6.1",
         "@claviska/jquery-minicolors": "2.3.6",
         "@github/markdown-toolbar-element": "2.1.1",
+        "@github/relative-time-element": "4.2.4",
         "@github/text-expander-element": "2.3.0",
         "@mcaptcha/vanilla-glue": "0.1.0-alpha-3",
         "@primer/octicons": "18.3.0",
@@ -851,6 +852,11 @@
       "resolved": "https://registry.npmjs.org/@github/markdown-toolbar-element/-/markdown-toolbar-element-2.1.1.tgz",
       "integrity": "sha512-J++rpd5H9baztabJQB82h26jtueOeBRSTqetk9Cri+Lj/s28ndu6Tovn0uHQaOKtBWDobFunk9b5pP5vcqt7cA=="
     },
+    "node_modules/@github/relative-time-element": {
+      "version": "4.2.4",
+      "resolved": "https://registry.npmjs.org/@github/relative-time-element/-/relative-time-element-4.2.4.tgz",
+      "integrity": "sha512-18qgH9FYUHYN9K3z4s35auDHww1dKTU6TacI8JkA5OuvHVa1lTMuSTZ4hIoJngD5+mizcoRMOs6p/yZYMIjsyg=="
+    },
     "node_modules/@github/text-expander-element": {
       "version": "2.3.0",
       "resolved": "https://registry.npmjs.org/@github/text-expander-element/-/text-expander-element-2.3.0.tgz",
diff --git a/package.json b/package.json
index 829b9f4ad0..57dcfc2f7f 100644
--- a/package.json
+++ b/package.json
@@ -13,6 +13,7 @@
     "@citation-js/plugin-software-formats": "0.6.1",
     "@claviska/jquery-minicolors": "2.3.6",
     "@github/markdown-toolbar-element": "2.1.1",
+    "@github/relative-time-element": "4.2.4",
     "@github/text-expander-element": "2.3.0",
     "@mcaptcha/vanilla-glue": "0.1.0-alpha-3",
     "@primer/octicons": "18.3.0",
diff --git a/routers/web/admin/admin.go b/routers/web/admin/admin.go
index 0a51000c70..9847a6d923 100644
--- a/routers/web/admin/admin.go
+++ b/routers/web/admin/admin.go
@@ -18,8 +18,6 @@ import (
 	"code.gitea.io/gitea/modules/process"
 	"code.gitea.io/gitea/modules/queue"
 	"code.gitea.io/gitea/modules/setting"
-	"code.gitea.io/gitea/modules/timeutil"
-	"code.gitea.io/gitea/modules/translation"
 	"code.gitea.io/gitea/modules/updatechecker"
 	"code.gitea.io/gitea/modules/web"
 	"code.gitea.io/gitea/services/cron"
@@ -34,7 +32,7 @@ const (
 )
 
 var sysStatus struct {
-	Uptime       string
+	StartTime    string
 	NumGoroutine int
 
 	// General statistics.
@@ -75,7 +73,7 @@ var sysStatus struct {
 }
 
 func updateSystemStatus() {
-	sysStatus.Uptime = timeutil.TimeSincePro(setting.AppStartTime, translation.NewLocale("en-US"))
+	sysStatus.StartTime = setting.AppStartTime.Format(time.RFC3339)
 
 	m := new(runtime.MemStats)
 	runtime.ReadMemStats(m)
diff --git a/templates/admin/auth/list.tmpl b/templates/admin/auth/list.tmpl
index c431c79cb5..3b8d17ff7d 100644
--- a/templates/admin/auth/list.tmpl
+++ b/templates/admin/auth/list.tmpl
@@ -29,8 +29,8 @@
 							<td><a href="{{AppSubUrl}}/admin/auths/{{.ID}}">{{.Name}}</a></td>
 							<td>{{.TypeName}}</td>
 							<td>{{if .IsActive}}{{svg "octicon-check"}}{{else}}{{svg "octicon-x"}}{{end}}</td>
-							<td><span data-tooltip-content="{{.UpdatedUnix.FormatShort}}"><time data-format="short-date" datetime="{{.UpdatedUnix.FormatLong}}">{{.UpdatedUnix.FormatShort}}</time></span></td>
-							<td><span data-tooltip-content="{{.CreatedUnix.FormatLong}}"><time data-format="short-date" datetime="{{.CreatedUnix.FormatLong}}">{{.CreatedUnix.FormatShort}}</time></span></td>
+							<td>{{template "shared/datetime/short" (dict "Datetime" .UpdatedUnix.FormatLong "Fallback" .UpdatedUnix.FormatShort)}}</td>
+							<td>{{template "shared/datetime/short" (dict "Datetime" .CreatedUnix.FormatLong "Fallback" .CreatedUnix.FormatShort)}}</td>
 							<td><a href="{{AppSubUrl}}/admin/auths/{{.ID}}">{{svg "octicon-pencil"}}</a></td>
 						</tr>
 					{{end}}
diff --git a/templates/admin/cron.tmpl b/templates/admin/cron.tmpl
index 29e4bc09bc..51685112ba 100644
--- a/templates/admin/cron.tmpl
+++ b/templates/admin/cron.tmpl
@@ -21,8 +21,8 @@
 						<td><button type="submit" class="ui green button" name="op" value="{{.Name}}" title="{{$.locale.Tr "admin.dashboard.operation_run"}}">{{svg "octicon-triangle-right"}}</button></td>
 						<td>{{$.locale.Tr (printf "admin.dashboard.%s" .Name)}}</td>
 						<td>{{.Spec}}</td>
-						<td>{{DateFmtLong .Next}}</td>
-						<td>{{if gt .Prev.Year 1}}{{DateFmtLong .Prev}}{{else}}N/A{{end}}</td>
+						<td>{{template "shared/datetime/full" (dict "Datetime" (DateFmtLong .Next) "Fallback" (DateFmtLong .Next) )}}</td>
+						<td>{{if gt .Prev.Year 1}}{{template "shared/datetime/full" (dict "Datetime" (DateFmtLong .Prev) "Fallback" (DateFmtLong .Prev) )}}{{else}}N/A{{end}}</td>
 						<td>{{.ExecTimes}}</td>
 						<td {{if ne .Status ""}}data-tooltip-content="{{.FormatLastMessage $.locale}}"{{end}} >{{if eq .Status ""}}—{{else if eq .Status "finished"}}{{svg "octicon-check" 16}}{{else}}{{svg "octicon-x" 16}}{{end}}</td>
 					</tr>
diff --git a/templates/admin/dashboard.tmpl b/templates/admin/dashboard.tmpl
index d2ba1e2b01..fc1b1f4385 100644
--- a/templates/admin/dashboard.tmpl
+++ b/templates/admin/dashboard.tmpl
@@ -83,7 +83,7 @@
 		<div class="ui attached table segment">
 			<dl class="dl-horizontal admin-dl-horizontal">
 				<dt>{{.locale.Tr "admin.dashboard.server_uptime"}}</dt>
-				<dd>{{.SysStatus.Uptime}}</dd>
+				<dd><relative-time format="duration" datetime="{{.SysStatus.StartTime}}">{{.SysStatus.StartTime}}</relative-time></dd>
 				<dt>{{.locale.Tr "admin.dashboard.current_goroutine"}}</dt>
 				<dd>{{.SysStatus.NumGoroutine}}</dd>
 				<div class="ui divider"></div>
diff --git a/templates/admin/notice.tmpl b/templates/admin/notice.tmpl
index bfe4762350..dd17bde036 100644
--- a/templates/admin/notice.tmpl
+++ b/templates/admin/notice.tmpl
@@ -29,7 +29,7 @@
 							<td>{{.ID}}</td>
 							<td>{{$.locale.Tr .TrStr}}</td>
 							<td class="view-detail"><span class="notice-description text truncate">{{.Description}}</span></td>
-							<td><span class="notice-created-time" data-tooltip-content="{{.CreatedUnix.AsTime}}"><time data-format="short-date" datetime="{{.CreatedUnix.FormatLong}}">{{.CreatedUnix.FormatShort}}</time></span></td>
+							<td>{{template "shared/datetime/short" (dict "Datetime" .CreatedUnix.FormatLong "Fallback" .CreatedUnix.FormatShort)}}</td>
 							<td><a href="#">{{svg "octicon-note" 16 "view-detail"}}</a></td>
 						</tr>
 					{{end}}
diff --git a/templates/admin/org/list.tmpl b/templates/admin/org/list.tmpl
index 9bf7a6268e..f114b90fc7 100644
--- a/templates/admin/org/list.tmpl
+++ b/templates/admin/org/list.tmpl
@@ -44,7 +44,7 @@
 							<td>{{.NumTeams}}</td>
 							<td>{{.NumMembers}}</td>
 							<td>{{.NumRepos}}</td>
-							<td><span title="{{.CreatedUnix.FormatLong}}"><time data-format="short-date" datetime="{{.CreatedUnix.FormatLong}}">{{.CreatedUnix.FormatShort}}</time></span></td>
+							<td>{{template "shared/datetime/short" (dict "Datetime" .CreatedUnix.FormatLong "Fallback" .CreatedUnix.FormatShort)}}</td>
 							<td><a href="{{.OrganisationLink}}/settings">{{svg "octicon-pencil"}}</a></td>
 						</tr>
 					{{end}}
diff --git a/templates/admin/packages/list.tmpl b/templates/admin/packages/list.tmpl
index bb36ca1ae3..121f575861 100644
--- a/templates/admin/packages/list.tmpl
+++ b/templates/admin/packages/list.tmpl
@@ -68,7 +68,7 @@
 							{{end}}
 							</td>
 							<td>{{FileSize .CalculateBlobSize}}</td>
-							<td><span title="{{.Version.CreatedUnix.FormatLong}}"><time data-format="short-date" datetime="{{.Version.CreatedUnix.FormatLong}}">{{.Version.CreatedUnix.FormatShort}}</time></span></td>
+							<td>{{template "shared/datetime/short" (dict "Datetime" .Version.CreatedUnix.FormatLong "Fallback" .Version.CreatedUnix.FormatShort)}}</td>
 							<td><a class="delete-button" href="" data-url="{{$.Link}}/delete?page={{$.Page.Paginater.Current}}&sort={{$.SortType}}" data-id="{{.Version.ID}}" data-name="{{.Package.Name}}" data-data-version="{{.Version.Version}}">{{svg "octicon-trash"}}</a></td>
 						</tr>
 					{{end}}
diff --git a/templates/admin/process-row.tmpl b/templates/admin/process-row.tmpl
index 477bf5a41e..8fd2d1af70 100644
--- a/templates/admin/process-row.tmpl
+++ b/templates/admin/process-row.tmpl
@@ -3,7 +3,7 @@
 		<div class="icon gt-ml-3 gt-mr-3">{{if eq .Process.Type "request"}}{{svg "octicon-globe" 16}}{{else if eq .Process.Type "system"}}{{svg "octicon-cpu" 16}}{{else}}{{svg "octicon-terminal" 16}}{{end}}</div>
 		<div class="content gt-f1">
 			<div class="header">{{.Process.Description}}</div>
-			<div class="description"><span title="{{DateFmtLong .Process.Start}}">{{TimeSince .Process.Start .root.locale}}</span></div>
+			<div class="description">{{TimeSince .Process.Start .root.locale}}</div>
 		</div>
 		<div>
 			{{if ne .Process.Type "system"}}
diff --git a/templates/admin/queue.tmpl b/templates/admin/queue.tmpl
index 19dd70da12..767c235a38 100644
--- a/templates/admin/queue.tmpl
+++ b/templates/admin/queue.tmpl
@@ -158,8 +158,8 @@
 					{{range .Queue.Workers}}
 					<tr>
 						<td>{{.Workers}}{{if .IsFlusher}}<span title="{{$.locale.Tr "admin.monitor.queue.flush"}}">{{svg "octicon-sync"}}</span>{{end}}</td>
-						<td>{{DateFmtLong .Start}}</td>
-						<td>{{if .HasTimeout}}{{DateFmtLong .Timeout}}{{else}}-{{end}}</td>
+						<td>{{template "shared/datetime/full" (dict "Datetime" (DateFmtLong .Start) "Fallback" (DateFmtLong .Start) )}}</td>
+						<td>{{if .HasTimeout}}{{template "shared/datetime/full" (dict "Datetime" (DateFmtLong .Timeout) "Fallback" (DateFmtLong .Timeout) )}}{{else}}-{{end}}</td>
 						<td>
 							<a class="delete-button" href="" data-url="{{$.Link}}/cancel/{{.PID}}" data-id="{{.PID}}" data-name="{{.Workers}}" title="{{$.locale.Tr "remove"}}">{{svg "octicon-trash"}}</a>
 						</td>
diff --git a/templates/admin/repo/list.tmpl b/templates/admin/repo/list.tmpl
index 11216b8c86..f8e2bbc844 100644
--- a/templates/admin/repo/list.tmpl
+++ b/templates/admin/repo/list.tmpl
@@ -83,7 +83,7 @@
 							<td>{{.NumForks}}</td>
 							<td>{{.NumIssues}}</td>
 							<td>{{FileSize .Size}}</td>
-							<td><span title="{{.CreatedUnix.FormatLong}}"><time data-format="short-date" datetime="{{.CreatedUnix.FormatLong}}">{{.CreatedUnix.FormatShort}}</time></span></td>
+							<td>{{template "shared/datetime/short" (dict "Datetime" .CreatedUnix.FormatLong "Fallback" .CreatedUnix.FormatShort)}}</td>
 							<td><a class="delete-button" href="" data-url="{{$.Link}}/delete?page={{$.Page.Paginater.Current}}&sort={{$.SortType}}" data-id="{{.ID}}" data-name="{{.Name}}">{{svg "octicon-trash"}}</a></td>
 						</tr>
 					{{end}}
diff --git a/templates/admin/stacktrace-row.tmpl b/templates/admin/stacktrace-row.tmpl
index e6d2e68cbb..15e51e4aca 100644
--- a/templates/admin/stacktrace-row.tmpl
+++ b/templates/admin/stacktrace-row.tmpl
@@ -13,7 +13,7 @@
 		</div>
 		<div class="content gt-f1">
 			<div class="header">{{.Process.Description}}</div>
-			<div class="description">{{if ne .Process.Type "none"}}<span title="{{DateFmtLong .Process.Start}}">{{TimeSince .Process.Start .root.locale}}</span>{{end}}</div>
+			<div class="description">{{if ne .Process.Type "none"}}{{TimeSince .Process.Start .root.locale}}{{end}}</div>
 		</div>
 		<div>
 			{{if or (eq .Process.Type "request") (eq .Process.Type "normal")}}
diff --git a/templates/admin/user/list.tmpl b/templates/admin/user/list.tmpl
index 88af2172b7..50b9d13619 100644
--- a/templates/admin/user/list.tmpl
+++ b/templates/admin/user/list.tmpl
@@ -94,9 +94,9 @@
 							<td>{{if .IsRestricted}}{{svg "octicon-check"}}{{else}}{{svg "octicon-x"}}{{end}}</td>
 							<td>{{if index $.UsersTwoFaStatus .ID}}{{svg "octicon-check"}}{{else}}{{svg "octicon-x"}}{{end}}</td>
 							<td>{{.NumRepos}}</td>
-							<td><span title="{{.CreatedUnix.FormatLong}}"><time data-format="short-date" datetime="{{.CreatedUnix.FormatLong}}">{{.CreatedUnix.FormatShort}}</time></span></td>
+							<td>{{template "shared/datetime/short" (dict "Datetime" .CreatedUnix.FormatLong "Fallback" .CreatedUnix.FormatShort)}}</td>
 							{{if .LastLoginUnix}}
-								<td><span title="{{.LastLoginUnix.FormatLong}}"><time data-format="short-date" datetime="{{.LastLoginUnix.FormatLong}}">{{.LastLoginUnix.FormatShort}}</time></span></td>
+								<td>{{template "shared/datetime/short" (dict "Datetime" .LastLoginUnix.FormatLong "Fallback" .LastLoginUnix.FormatShort)}}</td>
 							{{else}}
 								<td><span>{{$.locale.Tr "admin.users.never_login"}}</span></td>
 							{{end}}
diff --git a/templates/explore/organizations.tmpl b/templates/explore/organizations.tmpl
index c763fcffc6..fe9359251b 100644
--- a/templates/explore/organizations.tmpl
+++ b/templates/explore/organizations.tmpl
@@ -23,7 +23,7 @@
 								{{svg "octicon-link"}}
 								<a href="{{.Website}}" rel="nofollow">{{.Website}}</a>
 							{{end}}
-							{{svg "octicon-clock"}} {{$.locale.Tr "user.join_on"}} <time data-format="short-date" datetime="{{.CreatedUnix.FormatLong}}">{{.CreatedUnix.FormatShort}}</time>
+							{{svg "octicon-clock"}} {{$.locale.Tr "user.join_on"}} {{template "shared/datetime/short" (dict "Datetime" .CreatedUnix.FormatLong "Fallback" .CreatedUnix.FormatShort)}}
 						</div>
 					</div>
 				</div>
diff --git a/templates/explore/users.tmpl b/templates/explore/users.tmpl
index aa397e65b7..5dbc4ef6e7 100644
--- a/templates/explore/users.tmpl
+++ b/templates/explore/users.tmpl
@@ -18,7 +18,7 @@
 								{{svg "octicon-mail"}}
 								<a href="mailto:{{.Email}}" rel="nofollow">{{.Email}}</a>
 							{{end}}
-							{{svg "octicon-clock"}} {{$.locale.Tr "user.join_on"}} <time data-format="short-date" datetime="{{.CreatedUnix.FormatLong}}">{{.CreatedUnix.FormatShort}}</time>
+							{{svg "octicon-clock"}} {{$.locale.Tr "user.join_on"}} {{template "shared/datetime/short" (dict "Datetime" .CreatedUnix.FormatLong "Fallback" .CreatedUnix.FormatShort)}}
 						</div>
 					</div>
 				</div>
diff --git a/templates/package/shared/cleanup_rules/preview.tmpl b/templates/package/shared/cleanup_rules/preview.tmpl
index c59ad67f77..f9c9bc71f0 100644
--- a/templates/package/shared/cleanup_rules/preview.tmpl
+++ b/templates/package/shared/cleanup_rules/preview.tmpl
@@ -22,7 +22,7 @@
 					<td><a href="{{.FullWebLink}}">{{.Version.Version}}</a></td>
 					<td><a href="{{.Creator.HomeLink}}">{{.Creator.Name}}</a></td>
 					<td>{{FileSize .CalculateBlobSize}}</td>
-					<td><span title="{{.Version.CreatedUnix.FormatLong}}"><time data-format="short-date" datetime="{{.Version.CreatedUnix.FormatLong}}">{{.Version.CreatedUnix.FormatShort}}</time></span></td>
+					<td>{{template "shared/datetime/short" (dict "Datetime" .Version.CreatedUnix.FormatLong "Fallback" .Version.CreatedUnix.FormatShort)}}</td>
 				</tr>
 			{{else}}
 				<tr>
diff --git a/templates/package/view.tmpl b/templates/package/view.tmpl
index beadcf5c1e..9677b8eb09 100644
--- a/templates/package/view.tmpl
+++ b/templates/package/view.tmpl
@@ -86,7 +86,7 @@
 							{{range .LatestVersions}}
 								<div class="item">
 									<a href="{{$.PackageDescriptor.PackageWebLink}}/{{PathEscape .LowerVersion}}">{{.Version}}</a>
-									<span class="text small">{{$.locale.Tr "packages.versions.on"}} {{.CreatedUnix.FormatDate}}</span>
+									<span class="text small">{{$.locale.Tr "on_date"}} {{.CreatedUnix.FormatDate}}</span>
 								</div>
 							{{end}}
 							</div>
diff --git a/templates/repo/activity.tmpl b/templates/repo/activity.tmpl
index ae1d426bc0..aa71fe838b 100644
--- a/templates/repo/activity.tmpl
+++ b/templates/repo/activity.tmpl
@@ -2,7 +2,7 @@
 <div role="main" aria-label="{{.Title}}" class="page-content repository commits">
 	{{template "repo/header" .}}
 	<div class="ui container">
-		<h2 class="ui header"><time data-format="date" datetime="{{.DateFrom}}">{{.DateFrom}}</time> - <time data-format="date" datetime="{{.DateUntil}}">{{.DateUntil}}</time>
+		<h2 class="ui header">{{template "shared/datetime/long" (dict "Datetime" .DateFrom "Fallback" .DateFrom)}} - {{template "shared/datetime/long" (dict "Datetime" .DateUntil "Fallback" .DateUntil)}}
 			<div class="ui right">
 				<!-- Period -->
 				<div class="ui floating dropdown jump filter">
diff --git a/templates/repo/issue/view_content/sidebar.tmpl b/templates/repo/issue/view_content/sidebar.tmpl
index 521d6ba1d3..a2f12083c6 100644
--- a/templates/repo/issue/view_content/sidebar.tmpl
+++ b/templates/repo/issue/view_content/sidebar.tmpl
@@ -385,7 +385,7 @@
 					<div class="gt-df gt-sb gt-ac">
 						<div class="due-date {{if .Issue.IsOverdue}}text red{{end}}" {{if .Issue.IsOverdue}}data-tooltip-content="{{.locale.Tr "repo.issues.due_date_overdue"}}"{{end}}>
 							{{svg "octicon-calendar" 16 "gt-mr-3"}}
-							<time data-format="date" datetime="{{.Issue.DeadlineUnix.FormatDate}}">{{.Issue.DeadlineUnix.FormatDate}}</time>
+							{{template "shared/datetime/long" (dict "Datetime" .Issue.DeadlineUnix.FormatDate "Fallback" .Issue.DeadlineUnix.FormatDate)}}
 						</div>
 						<div>
 							{{if and .HasIssuesOrPullsWritePermission (not .Repository.IsArchived)}}
diff --git a/templates/repo/settings/deploy_keys.tmpl b/templates/repo/settings/deploy_keys.tmpl
index 952d1b8418..33f3937201 100644
--- a/templates/repo/settings/deploy_keys.tmpl
+++ b/templates/repo/settings/deploy_keys.tmpl
@@ -64,7 +64,7 @@
 									{{.Fingerprint}}
 								</div>
 								<div class="activity meta">
-									<i>{{$.locale.Tr "settings.add_on"}} <span><time data-format="short-date" datetime="{{.CreatedUnix.FormatLong}}">{{.CreatedUnix.FormatShort}}</time></span> —  {{svg "octicon-info"}} {{if .HasUsed}}{{$.locale.Tr "settings.last_used"}} <span {{if .HasRecentActivity}}class="green"{{end}}><time data-format="short-date" datetime="{{.UpdatedUnix.FormatLong}}">{{.UpdatedUnix.FormatShort}}</time></span>{{else}}{{$.locale.Tr "settings.no_activity"}}{{end}} - <span>{{$.locale.Tr "settings.can_read_info"}}{{if not .IsReadOnly}} / {{$.locale.Tr "settings.can_write_info"}} {{end}}</span></i>
+									<i>{{$.locale.Tr "settings.add_on"}} <span>{{template "shared/datetime/short" (dict "Datetime" .CreatedUnix.FormatLong "Fallback" .CreatedUnix.FormatShort)}}</span> —  {{svg "octicon-info"}} {{if .HasUsed}}{{$.locale.Tr "settings.last_used"}} <span {{if .HasRecentActivity}}class="green"{{end}}>{{template "shared/datetime/short" (dict "Datetime" .UpdatedUnix.FormatLong "Fallback" .UpdatedUnix.FormatShort)}}</span>{{else}}{{$.locale.Tr "settings.no_activity"}}{{end}} - <span>{{$.locale.Tr "settings.can_read_info"}}{{if not .IsReadOnly}} / {{$.locale.Tr "settings.can_write_info"}} {{end}}</span></i>
 								</div>
 							</div>
 						</div>
diff --git a/templates/repo/settings/options.tmpl b/templates/repo/settings/options.tmpl
index 023be5cee4..1aaf58ee91 100644
--- a/templates/repo/settings/options.tmpl
+++ b/templates/repo/settings/options.tmpl
@@ -93,7 +93,7 @@
 						<tr>
 							<td>{{(MirrorRemoteAddress $.Context .Repository .Mirror.GetRemoteName false).Address}}</td>
 							<td>{{$.locale.Tr "repo.settings.mirror_settings.direction.pull"}}</td>
-							<td><time data-format="date-time" datetime="{{.Mirror.UpdatedUnix.FormatLong}}">{{.Mirror.UpdatedUnix.AsTime}}</time></td>
+							<td>{{template "shared/datetime/full" (dict "Datetime" .Mirror.UpdatedUnix.FormatLong "Fallback" .Mirror.UpdatedUnix.AsTime)}}</td>
 							<td class="right aligned">
 								<form method="post" style="display: inline-block">
 									{{.CsrfTokenHtml}}
@@ -171,7 +171,7 @@
 							{{$address := MirrorRemoteAddress $.Context $.Repository .GetRemoteName true}}
 							<td>{{$address.Address}}</td>
 							<td>{{$.locale.Tr "repo.settings.mirror_settings.direction.push"}}</td>
-							<td>{{if .LastUpdateUnix}}<time data-format="date-time" datetime="{{.LastUpdateUnix.FormatLong}}">{{.LastUpdateUnix.AsTime}}</time>{{else}}{{$.locale.Tr "never"}}{{end}} {{if .LastError}}<div class="ui red label" data-tooltip-content="{{.LastError}}">{{$.locale.Tr "error"}}</div>{{end}}</td>
+							<td>{{if .LastUpdateUnix}}{{template "shared/datetime/full" (dict "Datetime" .LastUpdateUnix.FormatLong "Fallback" .LastUpdateUnix.AsTime)}}{{else}}{{$.locale.Tr "never"}}{{end}} {{if .LastError}}<div class="ui red label" data-tooltip-content="{{.LastError}}">{{$.locale.Tr "error"}}</div>{{end}}</td>
 							<td class="right aligned">
 								<form method="post" style="display: inline-block">
 									{{$.CsrfTokenHtml}}
diff --git a/templates/repo/user_cards.tmpl b/templates/repo/user_cards.tmpl
index b7bc3060b2..a48fd41744 100644
--- a/templates/repo/user_cards.tmpl
+++ b/templates/repo/user_cards.tmpl
@@ -18,7 +18,7 @@
 					{{else if .Location}}
 						{{svg "octicon-location"}} {{.Location}}
 					{{else}}
-						{{svg "octicon-clock"}} {{$.locale.Tr "user.join_on"}} <time data-format="short-date" datetime="{{.CreatedUnix.FormatLong}}">{{.CreatedUnix.FormatShort}}</time>
+						{{svg "octicon-clock"}} {{$.locale.Tr "user.join_on"}} {{template "shared/datetime/short" (dict "Datetime" .CreatedUnix.FormatLong "Fallback" .CreatedUnix.FormatShort)}}
 					{{end}}
 				</div>
 			</li>
diff --git a/templates/shared/datetime/full.tmpl b/templates/shared/datetime/full.tmpl
new file mode 100644
index 0000000000..1c55a4b53e
--- /dev/null
+++ b/templates/shared/datetime/full.tmpl
@@ -0,0 +1 @@
+<relative-time format="datetime" weekday="" year="numeric" month="short" day="numeric" hour="numeric" minute="numeric" second="numeric" datetime="{{.Datetime}}">{{.Fallback}}</relative-time>
diff --git a/templates/shared/datetime/long.tmpl b/templates/shared/datetime/long.tmpl
new file mode 100644
index 0000000000..4880cf3f91
--- /dev/null
+++ b/templates/shared/datetime/long.tmpl
@@ -0,0 +1 @@
+<relative-time format="datetime" year="numeric" month="long" day="numeric" weekday="" datetime="{{.Datetime}}">{{.Fallback}}</relative-time>
diff --git a/templates/shared/datetime/short.tmpl b/templates/shared/datetime/short.tmpl
new file mode 100644
index 0000000000..e5bcef6459
--- /dev/null
+++ b/templates/shared/datetime/short.tmpl
@@ -0,0 +1 @@
+<relative-time format="datetime" year="numeric" month="short" day="numeric" weekday="" datetime="{{.Datetime}}">{{.Fallback}}</relative-time>
diff --git a/templates/shared/issuelist.tmpl b/templates/shared/issuelist.tmpl
index 35994fc435..198e76f37c 100644
--- a/templates/shared/issuelist.tmpl
+++ b/templates/shared/issuelist.tmpl
@@ -106,7 +106,7 @@
 						<span class="due-date" data-tooltip-content="{{$.locale.Tr "repo.issues.due_date"}}">
 							<span{{if .IsOverdue}} class="overdue"{{end}}>
 								{{svg "octicon-calendar" 14 "gt-mr-2"}}
-								<time data-format="short-date" datetime="{{.DeadlineUnix.FormatDate}}">{{.DeadlineUnix.FormatShort}}</time>
+								{{template "shared/datetime/short" (dict "Datetime" .DeadlineUnix.FormatDate "Fallback" .DeadlineUnix.FormatShort)}}
 							</span>
 						</span>
 					{{end}}
diff --git a/templates/user/profile.tmpl b/templates/user/profile.tmpl
index e0e05575fa..9bde03f001 100644
--- a/templates/user/profile.tmpl
+++ b/templates/user/profile.tmpl
@@ -73,7 +73,7 @@
 									</li>
 								{{end}}
 							{{end}}
-							<li>{{svg "octicon-clock"}} {{.locale.Tr "user.join_on"}} <time data-format="short-date" datetime="{{.Owner.CreatedUnix.FormatLong}}">{{.Owner.CreatedUnix.FormatShort}}</time></li>
+							<li>{{svg "octicon-clock"}} {{.locale.Tr "user.join_on"}} {{template "shared/datetime/short" (dict "Datetime" .Owner.CreatedUnix.FormatLong "Fallback" .Owner.CreatedUnix.FormatShort)}}</li>
 							{{if and .Orgs .HasOrgsVisible}}
 							<li>
 								<ul class="user-orgs">
diff --git a/templates/user/settings/applications.tmpl b/templates/user/settings/applications.tmpl
index 23cd111229..2694f5cad0 100644
--- a/templates/user/settings/applications.tmpl
+++ b/templates/user/settings/applications.tmpl
@@ -30,7 +30,7 @@
 								</ul>
 							</details>
 							<div class="activity meta">
-								<i>{{$.locale.Tr "settings.add_on"}} <span><time data-format="short-date" datetime="{{.CreatedUnix.FormatLong}}">{{.CreatedUnix.FormatShort}}</time></span> — {{svg "octicon-info"}} {{if .HasUsed}}{{$.locale.Tr "settings.last_used"}} <span {{if .HasRecentActivity}}class="green"{{end}}><time data-format="short-date" datetime="{{.UpdatedUnix.FormatLong}}">{{.UpdatedUnix.FormatShort}}</time></span>{{else}}{{$.locale.Tr "settings.no_activity"}}{{end}}</i>
+								<i>{{$.locale.Tr "settings.add_on"}} <span>{{template "shared/datetime/short" (dict "Datetime" .CreatedUnix.FormatLong "Fallback" .CreatedUnix.FormatShort)}}</span> — {{svg "octicon-info"}} {{if .HasUsed}}{{$.locale.Tr "settings.last_used"}} <span {{if .HasRecentActivity}}class="green"{{end}}>{{template "shared/datetime/short" (dict "Datetime" .UpdatedUnix.FormatLong "Fallback" .UpdatedUnix.FormatShort)}}</span>{{else}}{{$.locale.Tr "settings.no_activity"}}{{end}}</i>
 							</div>
 						</div>
 					</div>
diff --git a/templates/user/settings/grants_oauth2.tmpl b/templates/user/settings/grants_oauth2.tmpl
index 0adc981683..3b92f35f37 100644
--- a/templates/user/settings/grants_oauth2.tmpl
+++ b/templates/user/settings/grants_oauth2.tmpl
@@ -20,7 +20,7 @@
 				<div class="content">
 					<strong>{{$grant.Application.Name}}</strong>
 					<div class="activity meta">
-						<i>{{$.locale.Tr "settings.add_on"}} <span><time data-format="short-date" datetime="{{$grant.CreatedUnix.FormatLong}}">{{$grant.CreatedUnix.FormatShort}}</time></span></i>
+						<i>{{$.locale.Tr "settings.add_on"}} <span>{{template "shared/datetime/short" (dict "Datetime" $grant.CreatedUnix.FormatLong "Fallback" $grant.CreatedUnix.FormatShort)}}</span></i>
 					</div>
 				</div>
 			</div>
diff --git a/templates/user/settings/keys_gpg.tmpl b/templates/user/settings/keys_gpg.tmpl
index 772fc4613b..9ba9199db7 100644
--- a/templates/user/settings/keys_gpg.tmpl
+++ b/templates/user/settings/keys_gpg.tmpl
@@ -68,9 +68,9 @@
 						<b>{{$.locale.Tr "settings.subkeys"}}:</b> {{range .SubsKey}} {{.PaddedKeyID}} {{end}}
 					</div>
 					<div class="activity meta">
-						<i>{{$.locale.Tr "settings.add_on"}} <span><time data-format="short-date" datetime="{{.AddedUnix.FormatLong}}">{{.AddedUnix.FormatShort}}</time></span></i>
+						<i>{{$.locale.Tr "settings.add_on"}} <span>{{template "shared/datetime/short" (dict "Datetime" .AddedUnix.FormatLong "Fallback" .AddedUnix.FormatShort)}}</span></i>
 						-
-						<i>{{if not .ExpiredUnix.IsZero}}{{$.locale.Tr "settings.valid_until"}} <span><time data-format="short-date" datetime="{{.ExpiredUnix.FormatLong}}">{{.ExpiredUnix.FormatShort}}</time></span>{{else}}{{$.locale.Tr "settings.valid_forever"}}{{end}}</i>
+						<i>{{if not .ExpiredUnix.IsZero}}{{$.locale.Tr "settings.valid_until"}} <span>{{template "shared/datetime/short" (dict "Datetime" .ExpiredUnix.FormatLong "Fallback" .ExpiredUnix.FormatShort)}}</span>{{else}}{{$.locale.Tr "settings.valid_forever"}}{{end}}</i>
 					</div>
 				</div>
 			</div>
diff --git a/templates/user/settings/keys_principal.tmpl b/templates/user/settings/keys_principal.tmpl
index a156306112..6194db13ab 100644
--- a/templates/user/settings/keys_principal.tmpl
+++ b/templates/user/settings/keys_principal.tmpl
@@ -25,7 +25,7 @@
 					<div class="content">
 						<strong>{{.Name}}</strong>
 						<div class="activity meta">
-							<i>{{$.locale.Tr "settings.add_on"}} <span><time data-format="short-date" datetime="{{.CreatedUnix.FormatLong}}">{{.CreatedUnix.FormatShort}}</time></span> —  {{svg "octicon-info" 16}} {{if .HasUsed}}{{$.locale.Tr "settings.last_used"}} <span {{if .HasRecentActivity}}class="green"{{end}}><time data-format="short-date" datetime="{{.UpdatedUnix.FormatLong}}">{{.UpdatedUnix.FormatShort}}</time></span>{{else}}{{$.locale.Tr "settings.no_activity"}}{{end}}</i>
+							<i>{{$.locale.Tr "settings.add_on"}} <span>{{template "shared/datetime/short" (dict "Datetime" .CreatedUnix.FormatLong "Fallback" .CreatedUnix.FormatShort)}}</span> —  {{svg "octicon-info" 16}} {{if .HasUsed}}{{$.locale.Tr "settings.last_used"}} <span {{if .HasRecentActivity}}class="green"{{end}}>{{template "shared/datetime/short" (dict "Datetime" .UpdatedUnix.FormatLong "Fallback" .UpdatedUnix.FormatShort)}}</span>{{else}}{{$.locale.Tr "settings.no_activity"}}{{end}}</i>
 						</div>
 					</div>
 				</div>
diff --git a/templates/user/settings/keys_ssh.tmpl b/templates/user/settings/keys_ssh.tmpl
index 160dedc93c..b60434cae4 100644
--- a/templates/user/settings/keys_ssh.tmpl
+++ b/templates/user/settings/keys_ssh.tmpl
@@ -59,7 +59,7 @@
 								{{.Fingerprint}}
 						</div>
 						<div class="activity meta">
-								<i>{{$.locale.Tr "settings.add_on"}} <span><time data-format="short-date" datetime="{{.CreatedUnix.FormatLong}}">{{.CreatedUnix.FormatShort}}</time></span> —	{{svg "octicon-info"}} {{if .HasUsed}}{{$.locale.Tr "settings.last_used"}} <span {{if .HasRecentActivity}}class="green"{{end}}><time data-format="short-date" datetime="{{.UpdatedUnix.FormatLong}}">{{.UpdatedUnix.FormatShort}}</time></span>{{else}}{{$.locale.Tr "settings.no_activity"}}{{end}}</i>
+								<i>{{$.locale.Tr "settings.add_on"}} <span>{{template "shared/datetime/short" (dict "Datetime" .CreatedUnix.FormatLong "Fallback" .CreatedUnix.FormatShort)}}</span> —	{{svg "octicon-info"}} {{if .HasUsed}}{{$.locale.Tr "settings.last_used"}} <span {{if .HasRecentActivity}}class="green"{{end}}>{{template "shared/datetime/short" (dict "Datetime" .UpdatedUnix.FormatLong "Fallback" .UpdatedUnix.FormatShort)}}</span>{{else}}{{$.locale.Tr "settings.no_activity"}}{{end}}</i>
 						</div>
 				</div>
 			</div>
diff --git a/tests/integration/repo_test.go b/tests/integration/repo_test.go
index 1765577999..5ddedfcf36 100644
--- a/tests/integration/repo_test.go
+++ b/tests/integration/repo_test.go
@@ -75,7 +75,10 @@ func testViewRepo(t *testing.T) {
 			}
 		})
 
-		f.commitTime, _ = s.Find("span.time-since").Attr("data-tooltip-content")
+		// convert "2017-06-14 21:54:21 +0800" to "Wed, 14 Jun 2017 13:54:21 UTC"
+		htmlTimeString, _ := s.Find("relative-time.time-since").Attr("datetime")
+		htmlTime, _ := time.Parse(time.RFC3339, htmlTimeString)
+		f.commitTime = htmlTime.UTC().Format("Mon, 02 Jan 2006 15:04:05 UTC")
 		items = append(items, f)
 	})
 
diff --git a/web_src/js/features/admin/common.js b/web_src/js/features/admin/common.js
index be5aa876a5..8f895152c7 100644
--- a/web_src/js/features/admin/common.js
+++ b/web_src/js/features/admin/common.js
@@ -178,7 +178,7 @@ export function initAdminCommon() {
     // Attach view detail modals
     $('.view-detail').on('click', function () {
       $detailModal.find('.content pre').text($(this).parents('tr').find('.notice-description').text());
-      $detailModal.find('.sub.header').text($(this).parents('tr').find('.notice-created-time').text());
+      $detailModal.find('.sub.header').text($(this).parents('tr').find('relative-time').attr('title'));
       $detailModal.modal('show');
       return false;
     });
diff --git a/web_src/js/features/formatting.js b/web_src/js/features/formatting.js
deleted file mode 100644
index 5590ba44d1..0000000000
--- a/web_src/js/features/formatting.js
+++ /dev/null
@@ -1,31 +0,0 @@
-const {lang} = document.documentElement;
-const dateFormatter = new Intl.DateTimeFormat(lang, {year: 'numeric', month: 'long', day: 'numeric'});
-const shortDateFormatter = new Intl.DateTimeFormat(lang, {year: 'numeric', month: 'short', day: 'numeric'});
-const dateTimeFormatter = new Intl.DateTimeFormat(lang, {year: 'numeric', month: 'short', day: 'numeric', hour: 'numeric', minute: 'numeric', second: 'numeric'});
-
-export function initFormattingReplacements() {
-  // for each <time></time> tag, if it has the data-format attribute, format
-  // the text according to the user's chosen locale and formatter.
-  formatAllTimeElements();
-}
-
-function formatAllTimeElements() {
-  const timeElements = document.querySelectorAll('time[data-format]');
-  for (const timeElement of timeElements) {
-    const formatter = getFormatter(timeElement.dataset.format);
-    timeElement.textContent = formatter.format(new Date(timeElement.dateTime));
-  }
-}
-
-function getFormatter(format) {
-  switch (format) {
-    case 'date':
-      return dateFormatter;
-    case 'short-date':
-      return shortDateFormatter;
-    case 'date-time':
-      return dateTimeFormatter;
-    default:
-      throw new Error('Unknown format');
-  }
-}
diff --git a/web_src/js/index.js b/web_src/js/index.js
index 878afb10d7..f7cbb24e85 100644
--- a/web_src/js/index.js
+++ b/web_src/js/index.js
@@ -74,7 +74,6 @@ import {initRepoBranchButton} from './features/repo-branch.js';
 import {initCommonOrganization} from './features/common-organization.js';
 import {initRepoWikiForm} from './features/repo-wiki.js';
 import {initRepoCommentForm, initRepository} from './features/repo-legacy.js';
-import {initFormattingReplacements} from './features/formatting.js';
 import {initCopyContent} from './features/copycontent.js';
 import {initCaptcha} from './features/captcha.js';
 import {initRepositoryActionView} from './components/RepoActionView.vue';
@@ -83,10 +82,6 @@ import {initGiteaFomantic} from './modules/fomantic.js';
 import {onDomReady} from './utils/dom.js';
 import {initRepoIssueList} from './features/repo-issue-list.js';
 
-// Run time-critical code as soon as possible. This is safe to do because this
-// script appears at the end of <body> and rendered HTML is accessible at that point.
-// TODO: replace them with CustomElements
-initFormattingReplacements();
 // Init Gitea's Fomantic settings
 initGiteaFomantic();
 
diff --git a/web_src/js/modules/tippy.js b/web_src/js/modules/tippy.js
index 0d57af4f0f..6cec95d766 100644
--- a/web_src/js/modules/tippy.js
+++ b/web_src/js/modules/tippy.js
@@ -6,7 +6,7 @@ export function createTippy(target, opts = {}) {
     animation: false,
     allowHTML: false,
     hideOnClick: false,
-    interactiveBorder: 30,
+    interactiveBorder: 20,
     ignoreAttributes: true,
     maxWidth: 500, // increase over default 350px
     arrow: `<svg width="16" height="7"><path d="m0 7 8-7 8 7Z" class="tippy-svg-arrow-outer"/><path d="m0 8 8-7 8 7Z" class="tippy-svg-arrow-inner"/></svg>`,
@@ -36,6 +36,8 @@ export function createTippy(target, opts = {}) {
  * @returns {null|tippy}
  */
 function attachTooltip(target, content = null) {
+  switchTitleToTooltip(target);
+
   content = content ?? target.getAttribute('data-tooltip-content');
   if (!content) return null;
 
@@ -55,6 +57,18 @@ function attachTooltip(target, content = null) {
   return target._tippy;
 }
 
+function switchTitleToTooltip(target) {
+  const title = target.getAttribute('title');
+  if (title) {
+    target.setAttribute('data-tooltip-content', title);
+    target.setAttribute('aria-label', title);
+    // keep the attribute, in case there are some other "[title]" selectors
+    // and to prevent infinite loop with <relative-time> which will re-add
+    // title if it is absent
+    target.setAttribute('title', '');
+  }
+}
+
 /**
  * Creating tooltip tippy instance is expensive, so we only create it when the user hovers over the element
  * According to https://www.w3.org/TR/DOM-Level-3-Events/#events-mouseevent-event-order , mouseover event is fired before mouseenter event
@@ -67,48 +81,57 @@ function lazyTooltipOnMouseHover(e) {
   attachTooltip(this);
 }
 
-/**
- * Activate the tooltip for all children elements
- * And if the element has no aria-label, use the tooltip content as aria-label
- * @param target {HTMLElement}
- */
-function attachChildrenLazyTooltip(target) {
-  for (const el of target.querySelectorAll('[data-tooltip-content]')) {
-    el.addEventListener('mouseover', lazyTooltipOnMouseHover, true);
+// Activate the tooltip for current element.
+// If the element has no aria-label, use the tooltip content as aria-label.
+function attachLazyTooltip(el) {
+  el.addEventListener('mouseover', lazyTooltipOnMouseHover, {capture: true});
 
-    // meanwhile, if the element has no aria-label, use the tooltip content as aria-label
-    if (!el.hasAttribute('aria-label')) {
-      const content = target.getAttribute('data-tooltip-content');
-      if (content) {
-        el.setAttribute('aria-label', content);
-      }
+  // meanwhile, if the element has no aria-label, use the tooltip content as aria-label
+  if (!el.hasAttribute('aria-label')) {
+    const content = el.getAttribute('data-tooltip-content');
+    if (content) {
+      el.setAttribute('aria-label', content);
     }
   }
 }
 
+// Activate the tooltip for all children elements.
+function attachChildrenLazyTooltip(target) {
+  for (const el of target.querySelectorAll('[data-tooltip-content]')) {
+    attachLazyTooltip(el);
+  }
+}
+
+const elementNodeTypes = new Set([Node.ELEMENT_NODE, Node.DOCUMENT_FRAGMENT_NODE]);
+
 export function initGlobalTooltips() {
-  // use MutationObserver to detect new elements added to the DOM, or attributes changed
-  const observer = new MutationObserver((mutationList) => {
-    for (const mutation of mutationList) {
+  // use MutationObserver to detect new "data-tooltip-content" elements added to the DOM, or attributes changed
+  const observerConnect = (observer) => observer.observe(document, {
+    subtree: true,
+    childList: true,
+    attributeFilter: ['data-tooltip-content', 'title']
+  });
+  const observer = new MutationObserver((mutationList, observer) => {
+    const pending = observer.takeRecords();
+    observer.disconnect();
+    for (const mutation of [...mutationList, ...pending]) {
       if (mutation.type === 'childList') {
         // mainly for Vue components and AJAX rendered elements
         for (const el of mutation.addedNodes) {
-          // handle all "tooltip" elements in added nodes which have 'querySelectorAll' method, skip non-related nodes (eg: "#text")
-          if ('querySelectorAll' in el) {
+          if (elementNodeTypes.has(el.nodeType)) {
             attachChildrenLazyTooltip(el);
+            if (el.hasAttribute('data-tooltip-content')) {
+              attachLazyTooltip(el);
+            }
           }
         }
       } else if (mutation.type === 'attributes') {
-        // sync the tooltip content if the attributes change
         attachTooltip(mutation.target);
       }
     }
+    observerConnect(observer);
   });
-  observer.observe(document, {
-    subtree: true,
-    childList: true,
-    attributeFilter: ['data-tooltip-content'],
-  });
+  observerConnect(observer);
 
   attachChildrenLazyTooltip(document.documentElement);
 }
diff --git a/web_src/js/webcomponents/README.md b/web_src/js/webcomponents/README.md
index 2b586a63d2..0fde507310 100644
--- a/web_src/js/webcomponents/README.md
+++ b/web_src/js/webcomponents/README.md
@@ -10,9 +10,3 @@ https://developer.mozilla.org/en-US/docs/Web/Web_Components
   so they should have their own dependencies and should be very light,
   then they won't affect the page loading time too much.
 * If the component is not a public one, it's suggested to have its own `Gitea` or `gitea-` prefix to avoid conflicts.
-
-# TODO
-
-There are still some components that are not migrated to web components yet:
-
-* `<time data-format>`
diff --git a/web_src/js/webcomponents/webcomponents.js b/web_src/js/webcomponents/webcomponents.js
index 5c4afb1eec..7e8135aa00 100644
--- a/web_src/js/webcomponents/webcomponents.js
+++ b/web_src/js/webcomponents/webcomponents.js
@@ -1,3 +1,4 @@
 import '@webcomponents/custom-elements'; // polyfill for some browsers like Pale Moon
+import '@github/relative-time-element';
 import './GiteaLocaleNumber.js';
 import './GiteaOriginUrl.js';