A forecasting or trading agent wants the market’s current probability for an event — the
odds. Those live on venues like Polymarket, Limitless and Manifold,
each with its own API shape. Here’s how an agent reads all three in one call, normalized.
§01 · one call, three venues
Ask a keyword, get the markets.
Instead of integrating each venue, an agent POSTs a keyword and gets back the matching live markets from Polymarket, Limitless and Manifold at once — each normalized to the same shape: the question, the outcome probabilities (0–1), USD volume, and the close date. Keyless, pay-per-call over x402.
prediction-markets
# Live prediction markets across Polymarket + Limitless + Manifold, in one call.
# ~$0.005 USDC over x402, no API key.
curl -s -X POST https://true402.dev/api/v1/prediction-markets \
-H 'content-type: application/json' \
-d '{"query": "election", "limit": 10}'
# → { query, count,
# venues: { ok: ["polymarket","limitless","manifold"], failed: [] },
# markets: [ { venue, question, url,
# outcomes: [ { name: "Yes", price: 0.62 }, { name: "No", price: 0.38 } ],
# volumeUsd, closesAt, closed } ] }
§02 · normalized probabilities
Comparable, not raw.
Every outcome comes back as an implied probability between 0 and 1, not raw venue units — so an agent can compare the same event across venues directly. Real-money USD volume is reported where the venue exposes it; Manifold trades play-money, so its volume is reported as null rather than a fabricated dollar figure.
§03 · fails soft
One venue down ≠ no answer.
The call fans out in parallel with a short timeout. If a venue is slow or down it lands in venues.failed and the rest still return — so an agent always knows its coverage and never gets blocked by one flaky upstream. The result is cached briefly, so repeated identical queries are cheap.
§04 · for agents
No key, no account, pay per call.
An unpaid request returns HTTP 402 with signed payment requirements; the agent pays ~$0.005 USDC on Base and retries. There is no API key and no signup — a wallet is the only identity. Pair it with true402’s other stalls (see the API reference) to build a full forecasting or trading loop. New to the protocol? What is x402?
§05 · questions
Answered for machines.
How can an AI agent get prediction-market odds via an API?
Point it at an endpoint that reads the venues for you and returns the odds as JSON. true402’s prediction-markets stall does this in one call: POST a keyword and it fans out to Polymarket, Limitless and Manifold, then returns the matching live markets normalized — each with the question, the outcome probabilities (0–1), USD volume, and the close date. It is pay-per-call over x402 with no API key and no account, so an autonomous agent can read odds without a human signing up for anything.
Is there a Polymarket API an agent can use without a key?
Polymarket’s public market data is readable without a key, but you still have to integrate each venue’s API shape and normalize it yourself. The prediction-markets stall does that aggregation for you across three venues at once and returns a single consistent schema — so an agent asks one question ("election", "bitcoin", "fed") and gets back the live markets from all of them, already normalized to comparable probabilities.
Why aggregate prediction markets across venues instead of one?
Different venues list different questions and price the same event slightly differently. Reading Polymarket, Limitless and Manifold together gives an agent broader coverage and lets it compare implied probabilities for the same event. The stall is tolerant of a venue being down — it returns whatever venues responded plus a venues.failed list, so one flaky API never blocks the answer.
What does a prediction-market data feed cost for a bot?
true402 prices the prediction-markets stall at about $0.005 in USDC per call, paid over x402 — no subscription, no key. An unpaid request returns HTTP 402 with signed payment requirements; the agent pays and retries. A forecasting or trading agent can poll it as often as it needs and pay only for the calls it makes.