Authentication

Every request to a SigIndex data endpoint requires the X-API-Key header. Your key is shown exactly once when you sign up; copy it to your service’s .env or password manager. If you lose it, regenerate from your Account page.

Examples

Substitute $SIGINDEX_KEY for the key from your Account page.

curl https://api.sigindex.com/api/v1/facility/110043804185 \
  -H "X-API-Key: $SIGINDEX_KEY"

Storing your key

Production services: Inject via your platform’s secret manager (Vercel env vars, AWS Secrets Manager, Railway env vars, Doppler, etc.). Never commit your key to a repository.
Local development: Store in .env.local and ensure that file is in your .gitignore.
Rotation: Regenerate from your Account page. The old key returns 401 immediately on the next call. Throttled to one regenerate per minute.

Failure modes

401 UNAUTHENTICATED — missing or invalid X-API-Key, or you sent a Bearer header (not accepted).
402 QUOTA_EXHAUSTED — free tier’s monthly call cap reached. Wait for the calendar-month reset or upgrade.
403 TIER_RESTRICTED — your key is valid but your tier doesn’t cover this endpoint (e.g., /area on Free).
429 RATE_LIMIT_EXCEEDED — monthly call limit hit. Inspect the Retry-After header (in seconds) or wait for the calendar-month reset.

Full error reference on the Errors page.