Register a webhook endpoint

Pro+. Body: {"url": "https://...", "events": ["event.announced", "fight.result", "card.changed", "event.completed", "odds.moved"]}. Subscribe to event.announced and you do not need to poll /v1/events to discover new cards — it fires once, within a minute of a card first landing in our data, and carries the same event object the list endpoint returns. fight.result fires once per bout within a minute of the result, as revision 1, and again as the next revision (corrected: true, with the previous result) whenever the winner, method, round, time or status is corrected in the 72 h after it — upsert on fight_id and keep the highest revision. odds.moved fires when the UFCalendar consensus line on an upcoming bout moves at least 5 implied-probability points on corner a, or the favourite flips, measured against the last line we delivered for that bout (its opening line before the first delivery), so a slow drift arrives once, not per refresh: data is {fight_id, event, fighter_a, fighter_b, odds: {consensus, opening, movement, updated_at}, previous, delta_points_a, direction, favourite_flipped, moved_at}. Information only, not betting advice. The response contains the signing secret ONCE. Every delivery body is {"id", "type", "data", "sent_at"} (WebhookDelivery schema) — id is stable across retries, so deduplicate on it. Deliveries carry X-UFCalendar-Signature: t=<unix>,v1=<hmac> where the HMAC-SHA256 input is "<t>.<rawBody>". Verify the timestamp too: reject anything where |now - t| exceeds 300 seconds, otherwise a captured delivery can be replayed at you forever with a valid HMAC. Delivery is at-least-once — expect a retry roughly every 60s until your endpoint returns 2xx. Endpoints auto-disable after 20 consecutive failures, and you may hold at most 3 active endpoints (409 endpoint_limit). Latency: results are dispatched within ~1 minute of the result being recorded. event.announced only fires for cards that have not started yet, so archive backfills never reach you as new-card noise. card.changed is filtered the same way: a change whose before and after read identically (a venue row re-minted for the same arena, a source dropping a sub-time it never knew) is never delivered, and when a source flip-flops a value we deliver the move and its undo once, not the twentieth repeat. Deliveries are free — they never count against your monthly request quota, only the calls you make to manage endpoints do.