COG downloads

Some collections' source files are hosted on Darly's own storage (currently the Mexico lidar COGs — agency-hosted collections like 3DEP and HRDEM have direct public URLs instead; see coverage). On plans with downloads enabled (Pro and up), you can download these files whole through /dl links.

Getting a download link

Fetch the single-item endpoint — Darly-hosted assets are rewritten to /dl links:

curl "https://api.darly.io/collections/mex-inegi-lidar-5m/items/{item_id}" \
  -H "X-API-Key: $DARLY_API_KEY"

{
  "assets": {
    "dtm": {
      "href": "https://api.darly.io/dl/mex-inegi-lidar-5m/{item_id}/dtm",
      "type": "image/tiff; application=geotiff; profile=cloud-optimized",
      "roles": ["data"]
    }
  }
}

Search and item-list responses omit Darly-hosted assets — always drill into the item. The /dl link itself is stable and never expires.

Downloading

GET /dl/{collection}/{item}/{asset} authenticates you, charges the file's size to your monthly data-out quota, and answers 302 with a short-lived signed URL. Any HTTP client that follows redirects just works:

curl -L -o tile.tif \
  "https://api.darly.io/dl/mex-inegi-lidar-5m/{item_id}/dtm" \
  -H "X-API-Key: $DARLY_API_KEY"

import os
import requests

resp = requests.get(
    "https://api.darly.io/dl/mex-inegi-lidar-5m/{item_id}/dtm",
    headers={"X-API-Key": os.environ["DARLY_API_KEY"]},
    allow_redirects=True,
)
resp.raise_for_status()
with open("tile.tif", "wb") as f:
    f.write(resp.content)

// fetch follows redirects by default
const resp = await fetch(
  "https://api.darly.io/dl/mex-inegi-lidar-5m/{item_id}/dtm",
  { headers: { "X-API-Key": process.env.DARLY_API_KEY } },
)
const buf = Buffer.from(await resp.arrayBuffer())

Metering rules

• Charged at full file size, once per download — against the same monthly data-out quota as raster extracts.
• The signed URL in the redirect lives 5 minutes — start the transfer promptly; re-hit the /dl link for a fresh one.
• 15-minute grace window: repeat requests for the same asset within 15 minutes redirect again without a second charge. This covers multi-open readers (GDAL/QGIS open files more than once) and HEAD-then-GET clients. After the window, a new request is a new charge.
• HEAD charges like GET (its redirect already exposes a live signed URL).
• Partial reads still pay the full file: /dl is for whole files. If you want a window, a mosaic, or a different projection, the raster endpoint meters actual bytes instead.

Errors