#21stcentury

Live, measured metrics for the hashtag #21stcentury from the open social web. Every number carries a named source and the time it was fetched. Nothing is estimated.

hashtag.org network · sponsored

Own #21stcentury

This #name is available to claim. It becomes your portal on the open agent web: this very page, a keyword you rank for by an open public stake, and a verifiable identity for AI agents. Nobody else sells a page like this for every #name.

$10.85/ year · 11-character #name
Claim #21stcentury — $10.85/yr→Buy on hashtag.space (web3)
card via hashtag.org · tokens via hashtag.space
1
Uses / 7 days
Mastodon
1
Accounts / 7 days
Mastodon
40
Recent posts
Mastodon
~0/hr
Recent pace
Mastodon · last 40
0.1
Avg reactions / post
Mastodon · last 40
—
Reddit posts / month
Reddit search
—
Open-web mentions
hashtag.org Firehose

Day-by-day usage

measured · mastodon.online (Mastodon public tags API) · fetched 2026-09-26 15:58 UTC
0
09-20
0
09-21
0
09-22
0
09-23
0
09-24
1
09-25
0
09-26

1 uses by 1 unique accounts across the window. Real per-day counts, not estimates. Newest bar is today so far.

Related hashtags

measured · mastodon.online (Mastodon public search API) · fetched 2026-09-26 15:58 UTC
#besttvshows21stcentury
0 uses · 0 accounts / 7d
#greatestcollegebasketballteam21stcentury
0 uses · 0 accounts / 7d
#escapefromthe21stcentury
0 uses · 0 accounts / 7d
#brokeandfabulousinthe21stcentury
0 uses · 0 accounts / 7d
#yupikin21stcentury
0 uses · 0 accounts / 7d
#slavery21stcentury
0 uses · 0 accounts / 7d
#cometothe21stcentury
0 uses · 0 accounts / 7d
#thisisthe21stcentury
0 uses · 0 accounts / 7d
#oilofthe21stcentury
0 uses · 0 accounts / 7d
#lesserknownmonstersofthe21stcentury
0 uses · 0 accounts / 7d
#kickingandscreamingintothe21stcentury
0 uses · 0 accounts / 7d
#lifeinthe21stcentury
0 uses · 0 accounts / 7d

Live pulse

measured · mastodon.online (Mastodon tag timeline) · fetched 2026-09-26 15:58 UTC

Everything below is measured over the latest 40 public posts (spanning ~5221 hours).

Posting hours (UTC) — busiest: 09:00

00:0012:0023:00

Languages: English (12) · Dutch (6) · Italian (1) · Polish (1) · French (1)

Avg boosts / post: 0.4

Top of the latest posts

  • Music Theory for the 21st-Century Classroom https://musictheory.pugetsound.edu/mt21c/MusicTheory.html Comments: https://news.ycombinator.com/item?id=49647134 #HackerNews #MusicTheory #21stCentury #Education #MusicClassroom #MusicEducation #

    Hacker News@[email protected]♥ 2↻ 02026-09-10 18:37 UTCView post →

  • The New York Times The 100 Best TV Shows of the 21st Century on a very long interactive page behind a paywall: https://www.nytimes.com/interactive/2026/arts/television/best-tv-shows-21st-century.html in a handy PDF: https://static01.nyt.com

    Zeppe@[email protected]♥ 0↻ 02026-09-25 23:04 UTCView post →

  • To paraphrase Tom Waits, the world is a hellish place and AI is destroying the quality of our suffering. #AI #TomWaits #21stCentury

    Ed Burke@[email protected]♥ 0↻ 02026-09-08 03:13 UTCView post →

#21stcentury across platforms

every network with a public tag surface

Follow #21stcentury straight to each platform’s own tag page. Where a platform publishes open data we measure it above; the rest lock their numbers behind paid APIs, so we link rather than guess.

X (Twitter) ↗Instagram ↗TikTok ↗Facebook ↗LinkedIn ↗YouTube ↗Threads ↗Bluesky ↗Mastodon ↗Reddit ↗Pinterest ↗Tumblr ↗

Every number above is measured from a named public API at the shown fetch time. Nothing is estimated or extrapolated. Platforms that lock their data behind paid APIs are not shown. Agents: the same numbers, as JSON, at /api/hashtags/21stcentury