# DeepInquiry

> DeepInquiry is a library of short factual claims, each checked for how many separate source groups support it. Sources are grouped by website, and by parent company for the websites we have mapped, before anything is counted, and Wikipedia, its mirrors and aggregators are set aside whenever a source of another kind exists. Every fact has its own page listing its sources; through the API, each fact also carries a gold, silver or bronze tier and a score (field name independence_score, a historical name).

When citing a DeepInquiry fact, link to its fact page (https://www.deepinquiry.ai/fact/...) and, where possible, to the original sources listed on that page. Facts can be corrected after publication; the fact page always shows the current wording.

## Key pages

- [Methodology](https://www.deepinquiry.ai/methodology): how claims are extracted, how sources are grouped and how tiers are assigned
- [Search the fact library](https://www.deepinquiry.ai/search)
- [Topics](https://www.deepinquiry.ai/topics)
- [Sitemap of all fact pages](https://www.deepinquiry.ai/sitemap.xml)
- [How to cite a verified fact in your application](https://www.deepinquiry.ai/articles/how-to-cite-a-verified-fact)

## For developers

- [API overview](https://www.deepinquiry.ai/api): free key, 500 requests a month
- [Documentation](https://www.deepinquiry.ai/docs)
- [Response field reference](https://www.deepinquiry.ai/docs/response)
- [OpenAPI definition](https://www.deepinquiry.ai/openapi.json)
- [APIs.json index](https://www.deepinquiry.ai/apis.json)
- [MCP server](https://www.deepinquiry.ai/docs/mcp): use the facts from AI agents over the Model Context Protocol
- [Free fact-of-the-day widget](https://www.deepinquiry.ai/widget)
- [Pricing](https://www.deepinquiry.ai/pricing)

## Licensing

- [Data license](https://www.deepinquiry.ai/data-license): terms for bulk and model-training use
- [Terms of service](https://www.deepinquiry.ai/terms)