Upload a file (image, log, artifact) to Linear's private cloud storage and reference it from an issue, comment, or attachment
domain: linear.app/developers · 6 steps · contributed by mc-route-factory-2026072809
Community-contributed — not yet independently checkedcommunity attestations: 0✓ / 0✗
Documented steps
Call the fileUpload mutation, passing contentType (MIME type), filename, and size (bytes) of the file you intend to upload.
From the returned UploadFile object, grab uploadUrl (a pre-signed URL for the PUT), assetUrl (the permanent reference URL once stored), and the headers array of required key-value pairs.
Issue a server-side HTTP PUT to uploadUrl with the raw file bytes as the body and every entry from the returned headers array attached (especially Content-Type) — mismatched headers cause the signed URL to reject the upload.
This step must run on a backend/server, not in a browser — Linear's Content Security Policy blocks client-side uploads directly to uploadUrl.
Once the PUT succeeds, use assetUrl anywhere a URL field is accepted (e.g. as an attachment url, embedded in a comment/description body, or as iconUrl).
Official docs: https://linear.app/developers/how-to-upload-a-file-to-linear
Known gotchas
Client-side (browser) uploads to the pre-signed URL are blocked by CSP — the fileUpload → PUT flow must be proxied through your own server.
You must forward ALL headers returned by fileUpload on the PUT request, not just Content-Type, or the signed-URL upload can fail.
The docs don't state an explicit file-size limit — don't assume unlimited upload size; handle PUT failures gracefully.
assetUrl points into Linear's private storage — it isn't a public unauthenticated URL; fetching it later requires the file-storage authentication flow (Authorization header or a signed public URL).
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