The /camli/ endpoint returns a blob the server knows about. A request with the GET verb will return 200 and the blob contents if present, 404 if not. A request with the HEAD verb will return 200 and the blob meta data (i.e., content-length), or 404 if the blob is not present. Get the blob: GET /camli/sha1-126249fd8c18cbb5312a5705746a2af87fba9538 HTTP/1.1 Host: example.com Response: HTTP/1.1 200 OK Content-Type: application/octet-stream Content-Length: Existence check: HEAD /camli/sha1-126249fd8c18cbb5312a5705746a2af87fba9538 HTTP/1.1 Host: example.com Response: HTTP/1.1 200 OK Content-Type: application/octet-stream Content-Length: Does not exist: GET /camli/sha1-126249fd8c18cbb5312a5705746a2af87fba9538 HTTP/1.1 Host: example.com Response: HTTP/1.1 404 OK