API reference
Documentation map
Every dataset, and where its documentation lives, is listed on one page: the documentation map. It is generated from the dataset registry and checked in CI, so a dataset cannot be published without documentation.
NGOpen
Federal spending, nonprofit, and legislative data. Five PostgREST APIs over PostgreSQL/PostGIS, designed to be joined — see the join paths and worked cross-dataset queries for how they connect.
- USAspending — Federal spending: prime awards, subawards, financial accounts, and agency references from USAspending.gov.
- IRS Nonprofits — IRS Exempt Organizations Business Master File, Form 990 SOI financials, Publication 78, auto-revocations, 990-N e-Postcards, 990 XML filings, Section 527 political organizations, and ACS census demographics.
- SAM Entity Registry — SAM.gov entity registrations for federal contractors and vendors.
- Congressional District Maps — UCLA PolySci’s congressional district boundaries for every Congress, served over PostGIS.
- Congress Legislators — @unitedstatesproject’s congress-legislators: members of Congress past and present, terms, committees, and district offices.
Parts
Vehicle, component, and identifier reference data. A separate collection with its own signed manifest; these datasets are not part of NGOpen.
- NHTSA vPIC Vehicle Information — official vPIC decoder tables, VIN decoding RPCs, and synchronized manufacturer, WMI, variable, model, and equipment-plant reference data.
Machine-readable references
Every endpoint has an OpenAPI specification, browsable at /swagger/ and served as JSON:
| Dataset | Specification |
|---|---|
| USAspending | /api/usaspending.json |
| IRS Nonprofits | /api/irs_ng.json |
| SAM Entity Registry | /api/samer.json |
| Congressional District Maps | /api/up_cdmaps.json |
| Congress Legislators | /api/usp_cl.json |
| NHTSA vPIC | /api/NHTSA.json |
Note the casing. Five specifications are lowercase; the NHTSA specification is uppercase, matching its
/parts/NHTSA/API path. The reference page and swagger page for NHTSA are lowercase, with uppercase aliases at/docs/NHTSA/and/swagger/NHTSA/.
Each dataset also publishes a signed BDP manifest describing its schema, provenance, and endpoints.