Create a work item attachment upload

POST/api/v2/workspaces/{slug}/projects/{project_id}/work-items/{work_item_id}/attachments/

Start an upload. This is the first of three steps. Send the file's metadata, not the file. The API creates the attachment with is_uploaded: false and returns a signed storage credential in upload_data. You then upload the file straight to storage and confirm the upload.

A successful call returns 200, not 201, and the body is an envelope rather than the bare attachment:

• upload_data holds the storage url and the form fields to send with the file.
• asset_id is the new attachment's id. Use it as {pk} when you confirm, read, or delete.
• asset_url is the attachment's relative path.
• attachment is the attachment object.

Path parameters

slug:requiredstring

The workspace slug. It appears in your Plane URLs. In https://app.plane.so/my-team/projects/, the slug is my-team.

project_id:requiredstring

The project the resource belongs to. Accepts the project UUID or its bare identifier, for example ENG.

work_item_id:requiredstring

The work item the resource belongs to. Accepts the work item UUID or its PROJ-123 identifier.

Body parameters

name:requiredstring

The file name.

size:requiredinteger

The file size in bytes. Must be at least 1.

external_id:optionalstring

Your system's identifier for this record, for sync and import correlation.

Nullable.

external_source:optionalstring

The system external_id came from, for example github or jira.

Nullable.

type:optionalstring

The file's MIME type, for example application/pdf. Defaults to application/octet-stream. A type the endpoint doesn't accept returns 400.

Response shaping

fields:optionalstring

Comma-separated list of fields to return. Fields you don't request are left out of the response instead of coming back as null. id is always included. Pass all to get every requestable field. An unknown field name returns 400. See Sparse fields.

Requestable here: asset_url, attributes, content_type, created_at, created_by_id, external_id, external_source, id, is_uploaded, name, size, updated_at, updated_by_id, work_item_id.

Scopes

projects.work_items.attachments:write

Errors

Status	Code	Cause
400	invalid_request	The request body or a query parameter failed validation.
401	unauthorized	Missing or invalid credentials.
402	payment_required	The feature this endpoint belongs to isn't enabled on your plan or is switched off.
403	forbidden	Your role or token scope doesn't allow this.
404	not_found	No such resource, or it's outside your tenant.
406	not_acceptable	The Accept header asks for a representation the API can't produce.
409	conflict	A business rule blocks the write.
413	payload_too_large	The request body is over the size limit.
415	unsupported_media_type	The Content-Type isn't one this endpoint accepts.
429	rate_limited	Throttled. Honor the Retry-After header before retrying.

Create a work item attachment upload

curl -X POST \
  "https://api.plane.so/api/v2/workspaces/my-team/projects/4af68566-94a4-4eb3-94aa-50dc9427067b/work-items/9c1f0b3d-6d2e-4c9a-8b41-2f7e5a0d6c88/attachments/" \
  -H "X-Api-Key: $PLANE_API_KEY" \
  -H "Content-Type: application/json" \
  -d '{
  "name": "design-review.pdf",
  "size": 482133,
  "external_id": null,
  "external_source": null,
  "type": "application/pdf"
}'

import requests

response = requests.post(
    "https://api.plane.so/api/v2/workspaces/my-team/projects/4af68566-94a4-4eb3-94aa-50dc9427067b/work-items/9c1f0b3d-6d2e-4c9a-8b41-2f7e5a0d6c88/attachments/",
    headers={"X-Api-Key": "your-api-key"},
    json={
        "name": "design-review.pdf",
        "size": 482133,
        "external_id": None,
        "external_source": None,
        "type": "application/pdf"
    },
)
print(response.json())

const response = await fetch(
  "https://api.plane.so/api/v2/workspaces/my-team/projects/4af68566-94a4-4eb3-94aa-50dc9427067b/work-items/9c1f0b3d-6d2e-4c9a-8b41-2f7e5a0d6c88/attachments/",
  {
    method: "POST",
    headers: {
      "X-Api-Key": "your-api-key",
      "Content-Type": "application/json",
    },
    body: JSON.stringify({
      name: "design-review.pdf",
      size: 482133,
      external_id: null,
      external_source: null,
      type: "application/pdf",
    }),
  },
);
const data = await response.json();

Response200

{
  "upload_data": {
    "url": "https://plane-uploads.s3.amazonaws.com/",
    "fields": {
      "Content-Type": "application/pdf",
      "key": "a3d1c5e7-2b4f-4a69-8c0d-7e5f1b3a9d24/5e8b1f0c9d2a4b7e8f3c6a1d0b9e2f47-design-review.pdf",
      "x-amz-algorithm": "AWS4-HMAC-SHA256",
      "x-amz-credential": "AKIAIOSFODNN7EXAMPLE/20260114/us-east-1/s3/aws4_request",
      "x-amz-date": "20260114T092241Z",
      "policy": "eyJleHBpcmF0aW9uIjoiMjAyNi0wMS0xNFQxMDoyMjo0MVoifQ==",
      "x-amz-signature": "6f1a9c2e4b7d0835a1e9f2c6b4d8a0e3f5c7b9d1a2e4f6081c3b5d7e9f0a2c4b"
    }
  },
  "asset_id": "8f4c2b1e-0d3a-4f7b-9c21-6e5a8b7d4f13",
  "asset_url": "/api/assets/v2/workspaces/my-team/projects/4af68566-94a4-4eb3-94aa-50dc9427067b/issues/9c1f0b3d-6d2e-4c9a-8b41-2f7e5a0d6c88/attachments/8f4c2b1e-0d3a-4f7b-9c21-6e5a8b7d4f13/",
  "attachment": {
    "id": "8f4c2b1e-0d3a-4f7b-9c21-6e5a8b7d4f13",
    "work_item_id": "9c1f0b3d-6d2e-4c9a-8b41-2f7e5a0d6c88",
    "name": "design-review.pdf",
    "content_type": "application/pdf",
    "size": 482133.0,
    "attributes": {
      "name": "design-review.pdf",
      "type": "application/pdf",
      "size": 482133
    },
    "asset_url": "/api/assets/v2/workspaces/my-team/projects/4af68566-94a4-4eb3-94aa-50dc9427067b/issues/9c1f0b3d-6d2e-4c9a-8b41-2f7e5a0d6c88/attachments/8f4c2b1e-0d3a-4f7b-9c21-6e5a8b7d4f13/",
    "is_uploaded": false,
    "external_id": null,
    "external_source": null,
    "created_at": "2026-01-14T09:22:41.478363Z",
    "updated_at": "2026-01-14T09:22:41.478363Z",
    "created_by_id": "16c61a3a-512a-48ac-b0be-b6b46fe6f430",
    "updated_by_id": null
  }
}