assets

Create a media-library asset

Uploads a file to the workspace's media library and returns its permanent public URL. Send a multipart/form-data body with the bytes in the file part.

The file's contents determine its type, and the type determines its kind:

KindAccepted formatsMaximum size
imagePNG, JPEG, GIF, WebP5 MB
videoMP4, WebM, QuickTime25 MB
audioMP3, M4A, Ogg, WAV25 MB
documentPDF25 MB

Images are re-encoded to remove embedded metadata and apply recorded rotation. Animated GIFs keep their animation, and WebP images become JPEG or PNG. Other files are stored byte-for-byte. Documents are downloads; other media displays inline. Asset bytes and URLs do not change. Upload new content as a new asset. A duplicate file returns the existing asset with 200 OK. An organization can retain at most 100,000 assets per region, including removed library entries whose URLs still serve. Reusing an existing asset does not use another slot.

Include each multipart field at most once. file is required. Optional name is a display name of up to 255 characters and defaults to the filename when omitted or empty after trimming; alt_text allows up to 1,000 characters; folder_id places a new asset in an existing folder. Omit folder_id for the library root. Each text part is limited to 8 KiB before trimming surrounding whitespace. Duplicate uploads retain the existing asset's metadata and folder.

See Manage media-library files for CLI and MCP use.

post/v1/assets

Request

  • Base URL: https://us1.platform.bird.com
  • URL: https://us1.platform.bird.com/v1/assets
  • Auth: one of:
    • HTTP bearer
    • API key in cookie bird_session

Headers

Idempotency-Keystring

Client-supplied key. On operations supporting request deduplication, a retained response is replayed for duplicate requests with the same key within the idempotency window (3 hours by default). This protection requires a workspace, organization, or staff-account scope. User-only and unscoped unauthenticated operations, streams, and operations with a separate replay contract do not use this response replay.

On a supported operation, if idempotency protection is unavailable before execution, the API returns 503 IdempotencyUnavailable (E01033) without executing this attempt. Retry with backoff using the same key and request. An operation that takes effect before its response is retained can still execute again on retry.

Two distinct 409 errors signal misuse:

  • request_in_progress (E01004): The same key is currently being processed by a concurrent request. Wait briefly and retry. The lock expires within 30 seconds.
  • idempotency_key_reuse (E01005): The same key has already completed against a different request body or method. Generate a new key.

Recommended key format is <event-type>/<entity-id> (for example welcome-user/usr_abc123).

X-Workspace-Idstring

Workspace context for the request. Required for dashboard authentication and master keys. Workspace keys and access tokens already identify their workspace; send that workspace or omit the header. A different one is rejected.

X-Organization-Idstring

Organization context for the request. Required for dashboard authentication. An API key or access token carries its own organization, so send either that organization or no header at all; a different one is rejected.

Response

An asset with identical contents already existed and was returned unchanged.

created_atstring date-time required
updated_atstring date-time required
idstring required
urlstring uri required

The asset's permanent public URL. Safe to embed or link in sent messages; for a document the usable form is a link.

thumbnail_urlstring uri nullable required

A small preview of the asset, for rendering a picker or a grid. Intended for your own interfaces rather than for embedding in messages. Null for every kind but image: generating a preview of a video, an audio file, or a document would mean rendering its contents, which the library does not do. Show an icon for the kind instead.

namestring required

The asset's display name. Defaults to the uploaded file's name.

content_typestring required

The stored file's media type, determined from its contents.

kindstring required

The category a media-library asset's type falls into. Use it to group or filter a mixed library.

  • image: covers PNG, JPEG, and GIF.
  • video: covers MP4, WebM, and QuickTime.
  • audio: covers MP3, M4A, Ogg, and WAV.
  • document: covers PDF.
size_bytesinteger required

The stored file's size in bytes. Images are re-encoded on upload, so for those this can differ from the size of the file you sent. Every other kind is stored byte-for-byte.

widthinteger nullable required

The stored image's width in pixels. Null for every kind but image.

heightinteger nullable required

The stored image's height in pixels. Null for every kind but image.

alt_textstring nullable required

Default alternative text describing the asset, carried along whenever it is placed. Most mail clients block images by default, so for an image this is often the only thing a recipient reads.

folder_idstring required
deleted_atstring date-time nullable required

When the asset was removed from the library, or null if it is still listed. A removed asset keeps serving at its original URL.

Example response

{
  "created_at": "2026-05-20T09:14:52Z",
  "updated_at": "2026-05-25T16:42:01Z",
  "id": "ast_01krdgeqcxet5s7t44vh8rt9mg",
  "kind": "image",
  "folder_id": "asf_01krdgeqcxet5s7t44vh8rt9mg"
}

Changes

No recorded changes to this operation across all 2 revisions of this API.