The FactFusion AI Facts API gives you our verified facts as JSON. It is free, read-only and needs no key. Every fact comes with its sources, their tier, the editor's confidence score and the date it was verified.
Base address:
https://factfusionai.com/wp-json/factfusion/v1
Try it: https://factfusionai.com/wp-json/factfusion/v1/random?category=space
Endpoints
All endpoints use GET. Category is a category slug such as space, ocean or animal (see /categories).
| Endpoint | Options | Returns |
|---|---|---|
/facts | page, per_page (1 to 50, default 20), category, include (list of IDs) | Verified facts, newest first. The total is in the X-WP-Total and X-WP-TotalPages headers. |
/facts/{id} | None | One fact, with its full explanation. |
/random | category, exclude (an ID) | One random fact, with its explanation. |
/search | q (at least 2 characters), limit (1 to 20) | Facts that match the words, with ID, title, claim and link. |
/categories | None | Every category with its fact count and page. |
/fact-of-the-day | None | Today's Fact of the Day. The same fact all day. |
What a fact looks like
{
"id": 189,
"number": 189,
"title": "A day on Venus is longer than its year",
"slug": "a-day-on-venus-is-longer-than-its-year",
"url": "https://factfusionai.com/fact/a-day-on-venus-is-longer-than-its-year/",
"claim": "…",
"short_answer": "…",
"category": { "slug": "space", "name": "Space", "icon": "…" },
"sources": [ { "name": "NASA", "title": "…", "url": "https://…", "tier": "A" } ],
"confidence": 90,
"verified_date": "2026-10-13",
"verified_by": "…",
"ai_assisted": true,
"embed_url": "…",
"explanation": "<p>…</p>"
}
Lists leave out explanation. ai_assisted is true when AI helped draft the wording; an editor still checked the fact against its source. Only published, verified facts are ever returned.
Example
fetch('https://factfusionai.com/wp-json/factfusion/v1/random?category=space')
.then(r => r.json())
.then(fact => console.log(fact.title, fact.sources[0].url));
The API answers requests from any website (CORS), so you can call it from a browser.
Limits and terms
- Up to 100 fact requests and 600 searches an hour from one IP address. Over the limit you get HTTP 429 with a Retry-After header.
- Need every fact? Download the open dataset instead of paging through the API.
- The facts are licensed CC BY 4.0. Show the fact’s source and link to the fact’s
urlon our site. - The API may change. Breaking changes will get a new version (
/factfusion/v2) and a note on our change log.