Developers

The Trueindex API

Free, public, no key required. Greater China market probabilities as JSON.

Every market on Trueindex is available as JSON over HTTPS. There is no registration, no API key, and no rate-limit tier to negotiate — point a request at it and read the numbers.

It exists because a forecast nobody can check is not much use. Journalists should be able to cite a number and have a reader verify it; researchers should be able to pull a series without scraping a page.

Authentication

None. All endpoints are public and read-only, and responses carry permissive CORS headers so you can call them directly from a browser, a notebook, or a newsroom dashboard without a proxy.

You do not need a Trueindex account to use the API. An account is only required to trade on the site itself.

curl https://trueindex.io/api/v1/stats

Endpoints

GET/api/v1/markets

List markets, newest and busiest first.

category — politics · technology · economy · cross-strait · hk-macau · overseas
status — open (default) · resolved · all
limit — 1–200, default 100

curl "https://trueindex.io/api/v1/markets?category=politics&limit=5"

GET/api/v1/markets/{slug}

A single market, including its recent probability history.

curl https://trueindex.io/api/v1/markets/smic-ships-3nm-by-2027

GET/api/v1/stats

Site-wide totals — the same figures the homepage header shows.

curl https://trueindex.io/api/v1/stats

Response shape

Every response is an object with data and meta. Prices come as an explicit probability between 0 and 1 alongside whole-cent prices, so there is no ambiguity about what the number means.

{
  "data": [
    {
      "slug": "smic-ships-3nm-by-2027",
      "url": "https://trueindex.io/markets/smic-ships-3nm-by-2027",
      "question": { "en": "Will SMIC ship a 3nm-class chip before end of 2027?" },
      "category": "technology",
      "status": "open",
      "probability": 0.4241,
      "price_cents": { "yes": 42, "no": 58 },
      "volume_24h": 797018628,
      "liquidity": 130000,
      "ends_at": "2027-12-29T21:20:09Z",
      "opening_book": true
    }
  ],
  "meta": {
    "api_version": "v1",
    "generated_at": "2026-08-30T20:50:38Z",
    "data_mode": "opening_book",
    "count": 1
  }
}

Data status

Markets flagged opening_book show platform-seeded opening liquidity, and meta.data_mode reads "opening_book". The flag clears itself once trading volume builds.

Fair use

Responses are cached at the edge for 60 seconds, so polling faster than that returns the same payload and helps nobody. There is no hard rate limit today; if that changes it will be announced here first, not enforced silently.

Terms

Free for commercial and non-commercial use, including in paid publications.
Attribution appreciated: “Source: Trueindex.io”, ideally linking to the market page in the url field.
Present opening_book figures as opening liquidity, not as participant volume.
No warranty. Prices are probabilistic and can be wrong; do not use them as the sole basis for a financial decision.

Questions, higher volumes, or a bulk export: [email protected]