SECTION

API

Read-only, public, no key. Live markets, public records and how Backd is split on any market.

Reference

Errors and limitsStatus codes, error codes and the rate limit.Read

Markets

GETList marketsOpen events, busiest first. Filter by category, league or a search word. Each event carries its top three markets; fetch the event for all of them.Read GETGet an eventOne event with every market, live prices in every odds format, and how Backd callers are split on each market.Read GETPrice historyThe chance of a market’s first outcome over time, for charts.Read GETLive matchesEvery match in play right now, with the score, the clock and the chance of each result.Read

Records

GETList callsPublic calls across Backd, newest first. Filter to one market to see who called it, and the split.Read GETGet a callOne public call, with any updates the caller added to their thesis.Read GETGet a recordSomeone’s public record: right %, profit per $10 staked, XP, streak and follows.Read GETSomeone’s callsA person’s public calls, newest first, optionally by status.Read GETLeaderboardPublic records ranked on settled calls.Read GETList combosPublic combos (2 to 10 picks in one slip, each its own position), newest first.Read

Utilities

GETConvert oddsOne chance in every odds format, with the payout on a $10 stake and the XP a right call would earn.Read

Everything public on Backd is JSON too. Live markets with prices in every odds format, public records and calls, combos, leaderboards, and how Backd callers are split on any market. No key, no sign-up. One request and you're in.

The basics

Base URL	`https://backd.market/api/v1`
Auth	None. Every endpoint is read-only and only returns what's set to everyone.
Rate limit	120 requests a minute per IP. Every response carries `x-ratelimit-limit`, `x-ratelimit-remaining` and `x-ratelimit-reset`.
CORS	Any origin. Call it straight from a browser.
Caching	Every response carries `cache-control`. Live data is 15 seconds, lists 30 to 60, odds an hour.
Numbers	Chances are 0 to 1. Money is in US dollars. Times are ISO 8601, or Unix seconds where marked.

Your first request

curl "https://backd.market/api/v1/markets?category=Football&limit=3"

Response

{
  "ok": true,
  "live": true,
  "count": 3,
  "events": [
    { "slug": "epl-ars-che-2026-10-04", "title": "Arsenal vs. Chelsea", "category": "Football",
      "markets": [ { "id": "4711001", "question": "Will Arsenal win on 2026-10-04?", "outcomes": [ { "name": "Yes", "chance": 0.58, "odds": { "percent": "58%", "decimal": "1.72", "fractional": "8/11", "american": "−138", "price": "58¢" } }, "…" ] } ],
      "url": "https://backd.market/match/epl-ars-che-2026-10-04" }
  ]
}

Common shapes

Every response is { "ok": true, ...data }. Errors are { "ok": false, "error": { "code", "message" } } with a matching status: 400 for a bad parameter, 404 when nothing matches, 429 when rate limited, 503 while records are unavailable. See errors.

Chance is always 0 to 1. Odds repeat the same chance as percent, decimal, fractional, american and price, so you never need to convert. profit_on_10 is profit per $10 staked: a normalised figure for comparing calls.

OpenAPI

The whole API is at /api/v1/openapi.json as OpenAPI 3.1, generated from the same spec as these pages. Point a client generator at it and you're done.

No writes yet. You can't back calls, build combos or send challenges from your own app. Backd's server writes every record itself at the live price, which is what keeps records honest. Tell us what you'd build and we'll look at a signed write API.