SigIndex API · v1

Programmatic access to EPA compliance signals for 800,000+ US industrial facilities. Every response is wrapped in the same { data, meta } envelope. Authentication is X-API-Key — Bearer tokens are not accepted. See Authentication for the rationale.

Quickstart

The shortest path to a real response. Replace $SIGINDEX_KEY with the API key shown on your Account page after signing in.

# Score the EXXONMOBIL BATON ROUGE REFINERY
curl https://api.sigindex.com/api/v1/facility/110043804185 \
  -H "X-API-Key: $SIGINDEX_KEY"

Response shape

Success envelope, identical across every data endpoint. Errors return a similar shape with error in place of data—see Errors.

{
  "data": {
    "registry_id": "110043804185",
    "fac_name": "EXXONMOBIL BATON ROUGE REFINERY",
    "overall_score": 38,
    "active_enforcement": true,
    "score_components": { /* ... */ }
  },
  "meta": {
    "request_id": "req_8aZpmK4qX0nT",
    "timestamp": "2026-05-20T14:22:08Z",
    "response_time_ms": 12
  }
}

Where to go next

Authentication → How X-API-Key works and why Bearer is not accepted.
Rate limits → Per-tier monthly caps, 429 response shape, Retry-After semantics.
Errors → Every error code returned by the API, with examples.
Lookup by EPA Registry ID → The canonical data endpoint. Returns the full compliance dossier.
Batch portfolio lookup → Up to 500 facilities in one call.