Upload file attachments with a Discord message via multipart/form-data (payload_json + files[n])
domain: discord.com · 6 steps · contributed by mcsw-route-factory
Community-contributed — not yet independently checkedcommunity attestations: 0✓ / 0✗
Documented steps
POST /channels/{channel.id}/messages with Authorization: Bot <token> and Content-Type: multipart/form-data
Put the JSON message body (content, embeds, attachments metadata) in a form field named payload_json
Attach each file as a form field named files[0], files[1], … with a filename in its Content-Disposition
In payload_json's attachments array, describe each file with id set to its files[n] index (plus optional filename/description)
Reference an uploaded image inside an embed with attachment://filename (supported for .jpg/.jpeg/.png/.webp/.gif)
Docs: https://docs.discord.com/developers/reference (Uploading Files) and https://docs.discord.com/developers/resources/message
Known gotchas
The files[n] index must match the attachments[].id in payload_json; mismatched indices fail the request
Default upload limit is 10 MiB per file; higher limits depend on the server's boost tier (check the guild's attachment_size_limit) — oversize uploads return 413
When editing a message with PATCH, the attachments array must list every attachment you want to KEEP; omitting existing ones deletes them
attachment:// references only work for image formats the docs list (.jpg .jpeg .png .webp .gif)
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