Getting started

Authentication

API keys, the three ways to send them, anonymous access, and how credits attach to your account.

What needs a key

Surface Anonymous With API key
STAC catalog (/collections, /search, …) ✓ 30 req/min per IP Higher limits
Elevation API (/v1/elevation/*) ✗ 401 ✓
COG downloads (/dl/...) ✗ 401 After your first credit purchase
/v1/health ✓ ✓

Keys are free: sign up, then create one under Dashboard → API keys. The full key is displayed once at creation.

Sending the key

Two equivalent forms; both are HTTP headers:

curl "https://api.darly.io/v1/elevation/point?lat=45.51&lon=-73.56" \
  -H "X-API-Key: $DARLY_API_KEY"

Keys are not accepted in the URL. A request with ?api_key=… is rejected with 401 rather than served anonymously: URLs are recorded by proxies, access logs, browser history, and Referer headers, so a key in a URL leaks at every hop.

For tools that take only a URL, most still let you attach headers. GDAL-based software (QGIS, rasterio, /vsicurl) reads them from an environment variable:

GDAL / rasterio / QGIS
export GDAL_HTTP_HEADERS="X-API-Key: $DARLY_API_KEY"
gdalinfo /vsicurl/https://api.darly.io/dl/usa-usgs-3dep-1m-seamless/<item>/dtm

Keys, users, and credits

  • Credits are per account, not per key. All keys you create (and your signed-in Explorer session) draw from the same credit balance and per-minute limits. Create as many keys as you want to separate environments or teammates' tools; revoking one never affects the others.
  • Revoke keys anytime in Dashboard → API keys; revocation is immediate.
  • What credits buy and every limit: credits & limits.

Auth errors

Case Response
Elevation call without authentication 401 {"detail": "Authentication is required for the elevation API"}
Download without authentication 401 {"detail": "Authentication is required to download assets"}
Invalid or revoked key Treated as anonymous: STAC keeps working at the anonymous limit; elevation calls get the 401s above
Your account doesn't include the endpoint 403 {"detail": "The current plan does not include this endpoint"}
Downloads before your first credit purchase 403 {"detail": "The current plan does not include downloads"}

A silent fallback to anonymous access on a bad key can be surprising: if STAC calls work but elevation calls return 401, check the key value first.