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Northstar Toolkit is the nonprofit data platform: every US nonprofit and foundation from IRS 990 filings, as free search, a developer API, and an MCP server for AI agents. The 990 base layer is free, and stays free.
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Documentation

Quickstarts, guides, and the full API reference for the nonprofit data API.

Quickstart

Your first API call in under a minute: keyless, then with a free key.

API Reference

Every endpoint, parameter, and response schema, generated from the API itself.

MCP / Agents

Point Claude or any MCP client at the warehouse. One URL, no key needed.