Attach existing asset

curl -X POST https://app.trypost.it/api/posts/9f1a2b3c-4d5e-6f7a-8b9c-0d1e2f3a4b5c/media/from-asset \
  -H "Authorization: Bearer YOUR_API_KEY" \
  -H "Content-Type: application/json" \
  -d '{
    "asset_id": "2681a1bf-131f-41b1-9866-755c1cb51f97",
    "alt": "Product hero shot"
  }'

{
  "id": "9f1a2b3c-4d5e-6f7a-8b9c-0d1e2f3a4b5c",
  "content": "Launch day!",
  "media": [
    {
      "id": "2681a1bf-131f-41b1-9866-755c1cb51f97",
      "path": "medias/2681a1bf-131f-41b1-9866-755c1cb51f97.jpg",
      "url": "https://media.trypost.it/medias/2681a1bf-131f-41b1-9866-755c1cb51f97.jpg",
      "type": "image",
      "mime_type": "image/jpeg",
      "original_filename": "hero.jpg",
      "size": 245760,
      "meta": {
        "width": 1920,
        "height": 1080,
        "alt_text": "Product hero shot"
      }
    }
  ],
  "status": "draft",
  "scheduled_at": null,
  "published_at": null,
  "platforms": [],
  "labels": [],
  "created_at": "2025-01-14 09:00:00",
  "updated_at": "2025-01-14 09:30:00"
}

POST

posts

{post}

media

from-asset

curl -X POST https://app.trypost.it/api/posts/9f1a2b3c-4d5e-6f7a-8b9c-0d1e2f3a4b5c/media/from-asset \
  -H "Authorization: Bearer YOUR_API_KEY" \
  -H "Content-Type: application/json" \
  -d '{
    "asset_id": "2681a1bf-131f-41b1-9866-755c1cb51f97",
    "alt": "Product hero shot"
  }'

{
  "id": "9f1a2b3c-4d5e-6f7a-8b9c-0d1e2f3a4b5c",
  "content": "Launch day!",
  "media": [
    {
      "id": "2681a1bf-131f-41b1-9866-755c1cb51f97",
      "path": "medias/2681a1bf-131f-41b1-9866-755c1cb51f97.jpg",
      "url": "https://media.trypost.it/medias/2681a1bf-131f-41b1-9866-755c1cb51f97.jpg",
      "type": "image",
      "mime_type": "image/jpeg",
      "original_filename": "hero.jpg",
      "size": 245760,
      "meta": {
        "width": 1920,
        "height": 1080,
        "alt_text": "Product hero shot"
      }
    }
  ],
  "status": "draft",
  "scheduled_at": null,
  "published_at": null,
  "platforms": [],
  "labels": [],
  "created_at": "2025-01-14 09:00:00",
  "updated_at": "2025-01-14 09:30:00"
}

Reuses a file already in the Asset Library. Nothing is uploaded. For a new file, use POST /posts/{post}/media or POST /posts/{post}/media/from-url. Owner, Admin, and Member can call this. Viewers get 403. Find IDs with GET /assets. MCP: attach-existing-asset-tool.

Path parameters

string

required

Post UUID. Must belong to this workspace. Otherwise 404.

Body parameters

string

required

Asset UUID from GET /assets. Must be a UUID. Missing, other-workspace, logo, or avatar IDs return 422 on asset_id: Asset not found.

string

Optional image alt text. Max 2000 characters. Ignored for video and PDF.

Send a non-empty alt to replace the library alt_text on this attachment.
Omit alt, or send null / "", to keep the library item’s existing alt_text.

Behaviour

The post must be draft or scheduled.
The file type must be allowed by every enabled platform on the post. If no platform is enabled, any type is allowed. Example: a post that only targets TikTok video rejects an image (422 on asset_id: This file type is not supported by the platforms enabled on the post.).
Calling again with the same asset_id does nothing: no duplicate, and alt is not updated.
The post stores a copy of the library fields (id, path, url, type, mime_type, original_filename, size, and meta when the library had any). If the library meta is empty, the post item has no meta key. The file on disk is shared — the same path as the library item.

Errors

Status	When
`403`	Viewer (or no permission to update the post)
`404`	Post not in this workspace
`422`	`asset_id` missing / not a UUID / not in this library (`Asset not found.`)
`422`	`alt` longer than 2000 characters
`422`	File type not allowed by the enabled platforms
`422`	Post is `published`, `partially_published`, `failed`, or `publishing` — `{ "message": "This post has already been processed and cannot be re-published. Duplicate it to try again." }`

Response

The updated post, same shape as GET /posts/{post}. The library item is now in media[].

curl -X POST https://app.trypost.it/api/posts/9f1a2b3c-4d5e-6f7a-8b9c-0d1e2f3a4b5c/media/from-asset \
  -H "Authorization: Bearer YOUR_API_KEY" \
  -H "Content-Type: application/json" \
  -d '{
    "asset_id": "2681a1bf-131f-41b1-9866-755c1cb51f97",
    "alt": "Product hero shot"
  }'

{
  "id": "9f1a2b3c-4d5e-6f7a-8b9c-0d1e2f3a4b5c",
  "content": "Launch day!",
  "media": [
    {
      "id": "2681a1bf-131f-41b1-9866-755c1cb51f97",
      "path": "medias/2681a1bf-131f-41b1-9866-755c1cb51f97.jpg",
      "url": "https://media.trypost.it/medias/2681a1bf-131f-41b1-9866-755c1cb51f97.jpg",
      "type": "image",
      "mime_type": "image/jpeg",
      "original_filename": "hero.jpg",
      "size": 245760,
      "meta": {
        "width": 1920,
        "height": 1080,
        "alt_text": "Product hero shot"
      }
    }
  ],
  "status": "draft",
  "scheduled_at": null,
  "published_at": null,
  "platforms": [],
  "labels": [],
  "created_at": "2025-01-14 09:00:00",
  "updated_at": "2025-01-14 09:30:00"
}

Overview

Posts

Platforms

Workspace

Assets

Signatures

Labels

Social Accounts

API Keys

Path parameters

Body parameters

Behaviour

Errors

Response

​Path parameters

​Body parameters

​Behaviour

​Errors

​Response

Path parameters

Body parameters

Behaviour

Errors

Response