Live Projects / Tool 01

EIN Due-Diligence Checker

In build · v1

Check any US nonprofit's IRS standing in seconds — one plain-English trust card with a green / amber / red verdict. An answer engine, not a database: verdict up front, evidence expandable, every field citing its source and "as of" date.

1,983,563organizations ingested from the IRS Business Master File
6IRS source files, pulled direct — never a re-publisher
9trap tests passing on every build
161,185reinstated orgs protected from a false "revoked" flag

What it checks — and what it doesn't

Checked in v1

  • 501(c)(3) status in the IRS Business Master File
  • Tax-deductibility per Publication 78 — including group-ruling subordinates
  • Revocation history, reconciled against reinstatements
  • Filing recency from the 990 e-file index and 990-N e-Postcards

Not evaluated yet

  • Charitable-registration status in the ~41 states that require it
  • 990 financial detail (revenue, spending, compensation)
  • News, litigation, or reputation signals

A diligence tool earns trust by saying "I didn't look" — never by implying "nothing there."

Build log

  1. Build rules, schema, and 98-code reference tables committedJul 2026
  2. IRS Business Master File ingested and verified — 1.98M orgs, church and known-EIN spot checks passingJul 2026
  3. Publication 78 + auto-revocation reconciliation, with trap tests that fail the build before they can mislabel an orgJul 2026
  4. Filing recency (990 e-file index + 990-N)
  5. Name search with match confidence
  6. Trust-card assembly and the deterministic rules engine
  7. Public checker launches on this page

Colophon — how this is built

Spec first: a full v1 build document with the correctness traps named before any code — group-ruling subordinates that look non-deductible, revoked-then-reinstated orgs that look revoked, churches that look like non-filers. Each trap is a test that fails the build, not the user.

Data comes from IRS.gov directly (Business Master File, Publication 78, the auto-revocation list, the 990 e-file index) — never from a re-publisher's API. Cards are precomputed monthly and served read-only, so there are no third-party calls at request time and no live database to corrupt: the warehouse builds a baked artifact, and the API serves it.

Built with AI in the loop, end to end — the same operating model I bring to organizations: spec → schema → verified 2M-row ingest in a working day, with human judgment on every gate that matters.

PythonPostgres + pg_trgmpolarsFastAPIBaked SQLite artifactGitHub Pages + Fly.io

Launching here.

The checker goes live on this page — free, no login, one search box. Building a nonprofit-facing product and want to compare notes, or want the verdict behind an org you fund? Email me.