Free Nonprofit Verification APIs
If your application needs to look up a nonprofit, resolve its EIN, or confirm that a submitted organization matches a real filing, the workflow usually has four steps.
Search by name, choose the right organization, save the EIN, and retrieve the latest filing. 501see supports this workflow on its free Developer plan. You can create an account, get an API key, and make your first request in about two minutes.
How the alternatives compare
The IRS Tax Exempt Organization Search is the authoritative source for formal tax-exempt status checks. It provides a search interface and downloadable records rather than an application-ready JSON API.
ProPublica’s Nonprofit Explorer API is free. Its documentation describes the API as a work in progress, and its database does not include organizations that only file Form 990-N.
CharityAPI offers a free, rate-limited plan and a $15 per month plan with name autocomplete and almost no rate limit.
501see provides a free Developer plan with name search, EIN lookup, and latest-filing lookup. It uses API-key authentication and returns structured JSON for application use.
Candid also offers a Charity Check API. Its documentation tells developers to contact an account manager for an API key.
Start free with 501see
The 501see Developer Free plan includes the complete basic workflow:
- Search for an organization by name, with optional location filters.
- Look up the organization by EIN.
- Retrieve its latest filing.
- Use an API key and structured JSON in your own application.
If you need lookup and verification inside an application, start with the free 501see Developer API. Two minutes is enough to find out whether it fits.