Official venue APIsAPIfree
Metaculus API: what it exposes, how it authenticates, where it stops
Last checked 2026-09-08
Metaculus is a forecasting platform, not an exchange: its API returns questions, community probabilities and prediction histories rather than tradable order books. The live reference is a Swagger UI at metaculus.com/api/, and the site itself is open source under BSD-2-Clause.
It is for researchers and forecasters who want structured probability data. Traders will not find orders, fills or a balance anywhere in it.
What the API exposes
The archived OpenAPI schema (version 1.0) lists /api2/questions/ with per-question routes for predict, prediction-history, prediction-for-date, predictions, download_csv, resolve and vote, plus bulk-predict. Around them sit projects (tournaments), categories, comments, notifications, reminders, user profiles and organizations.
An unauthenticated request to any /api2 or /api path today returns a permission error stating the API is only available to authenticated users, so everything, including reads, needs a token. The schema also lists proxy routes for Anthropic and OpenAI chat completions and a gpt-forecast endpoint, which points at how Metaculus is using the API internally for AI forecasting.
Authentication and rate limits
Generate a token on your account settings page under API Access and send it as Authorization: Token {token}. The schema notes that cookie authentication from the 2020 to 2023 era is still supported.
The schema states requests are throttled to 1,000 per hour. No burst or per-endpoint figures are published.
Pricing and access
No charge. Anyone with a Metaculus account can create a token. Questions and ideas go to api-requests@metaculus.com.
The full schema and Redoc page return 403 to anonymous requests; the figures on this page come from the Swagger landing page (which loads), the live permission-error response, and a 2025 Wayback Machine copy of the OpenAPI document.
Where it falls short
There is nothing to trade. Probabilities are community aggregates, not prices you can hit.
Documentation is behind login, and the schema warns that backward compatibility is not guaranteed as the tooling changes.
1,000 requests per hour rules out any high-frequency polling of question histories.
Who should use it
Quant researchers comparing crowd forecasts against venue prices, and forecasters automating their own submissions through the predict and bulk-predict routes. The per-question download_csv route is the quickest way to pull a full history for one question.
Anyone building a trading signal should treat it as a slow-moving reference feed alongside a real exchange API.
Questions about Metaculus API
Is the Metaculus API free?
Yes, with an account. Create a token under API Access in settings and send it as Authorization: Token.
Can I trade on Metaculus through the API?
No. Metaculus is a forecasting platform. The API exposes questions, predictions and community probabilities, not orders or money.
What is the Metaculus API rate limit?
The published schema states 1,000 requests per hour.
Where are the Metaculus API docs?
A Swagger UI at metaculus.com/api/ and a Redoc page under /api2/schema/redoc/, both of which require a logged-in session to load the schema.
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