OG Roulette

OG Roulette

Randomized Open Graph Link Previews.

Text this link to a friend to generate a random art preview.

After texting or posting the link to this website, a social crawler will<br>scrape the URL and receive a 302 to a permalink whose Open Graph tags embed<br>a random public-domain artwork, from either the Met or the Cleveland Museum<br>of Art. On apps like iMessage, Signal, WhatsApp, Google Messages, and<br>Bluesky the plain URL re-rolls to a new piece on every send; a few platforms<br>(Facebook, X, Slack, and Discord) cache the preview by URL, so a unique token<br>link (below) keeps those shares fresh too. Human visitors are redirected here.

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Posting to Social Media?

Sites like Facebook, X, and Slack cache the preview per URL, so the plain link would show everyone the same artwork. A token makes each share a fresh URL their cache hasn&rsquo;t seen, so every post gets a different piece.

Copy unique share URL

The share URL is https://roulette.vaguespac.es/s/, a random five-char base62 token per click that dodges Group B preview caches (see below). The same token always resolves to the same artwork, so a given link stays consistent for everyone who opens it.

User Agents

Every HTTP request carries a User-Agent header naming the<br>software that made it: a browser, a bot, an app. Servers read it to<br>decide how to respond. OG Roulette uses it to tell link-preview crawlers<br>(facebookexternalhit, Bluesky Cardyb, …) apart<br>from human browsers: crawlers get the 302 to an Open Graph permalink,<br>humans get this page.

The term is old. In networking the client acting on your behalf is<br>literally a “user agent,” and early HTTP sent it so servers could adapt<br>to client capabilities. Then 1990s servers began sniffing it to serve<br>rich content only to Netscape, whose UA started Mozilla/…,<br>so every other browser copied that prefix to pass the check. That<br>cargo-cult is why nearly every browser still claims to be “Mozilla”<br>today. A UA is only a header, though (trivially spoofed, and now being<br>frozen for privacy), so detecting crawlers by it is best-effort. That is<br>why OG Roulette also embeds real Open Graph tags in this page, so any<br>fetcher reading meta straight from the HTML still gets a card.

Two Kinds of Link Preview

Whether a shared link re-rolls its artwork depends on where and<br>when the preview is fetched.

Client-side, at compose time (Group A). Your own device<br>fetches the URL as you write the message and embeds the card into it.<br>There is no shared cache, so every send fetches fresh; even a constant<br>URL re-rolls. iMessage, Signal, WhatsApp, Google Messages, and Bluesky.

Central server, cached per URL (Group B). A backend bot<br>scrapes the URL once and caches the card keyed by that URL; everyone who<br>shares it sees the same card until the cache expires. Facebook, X,<br>LinkedIn, Slack, Discord, Telegram, and Reddit. A fresh token per share is a<br>URL their cache has never seen, so it misses and scrapes fresh, which is<br>how OG Roulette stays random even here.

Posting to Social Media?

Easiest path: share the plain URL https://roulette.vaguespac.es on a<br>Group A app: iMessage, Signal, WhatsApp, Google Messages, or Bluesky.<br>They fetch each preview fresh with no shared cache, so the bare link<br>re-rolls on every send. No token required.

The token only exists for Group B platforms (Facebook, X, LinkedIn,<br>Slack, Discord, Telegram, and Reddit), which cache previews by URL; there<br>the plain link would freeze to a single artwork for everyone. On those,<br>use the Copy unique share URL button above to<br>mint a unique /s/ that dodges the cache.

Other Uses

The mechanism is general: a preview rendered server-side at scrape time,<br>with the share itself as the trigger. Anything that can key off a fresh,<br>unique URL can ride on it.

For example, a generative art project could mint a new work only when<br>someone shares it to social media, using the token in each share URL as<br>the seed, so every post reveals a different, one-off piece. Other<br>possibilities in the same vein: live-data cards, token-numbered limited<br>editions, or a reveal that fires only the moment a link goes public.