Composite captions onto images

POST

/public/v1/slides/composite

curl --request POST \
  --url https://api.loomta.com/public/v1/slides/composite \
  --header 'Authorization: Bearer <token>' \
  --header 'Content-Type: application/json' \
  --data '{ "slides": [ { "index": 0, "mediaId": "a1d4e9b2-3c5f-4a8d-b0e1-2f6c7a9d8b3e", "caption": "Reason 1" } ], "captionSize": "medium" }'

• Production

Bakes captions onto already-uploaded images, producing new composited media. Feed the returned mediaIds into POST /posts.

Authorizations

• apiKey

Request Body^required

Media typeapplication/json

object

slides

required

Array<object>

>= 1 items <= 35 items

object

index

required

integer

mediaId

required

string format: uuid

caption

required

string

>= 1 characters <= 500 characters

captionSize

string

default: medium

Allowed values: small medium large

Example

{
  "slides": [
    {
      "index": 0,
      "mediaId": "a1d4e9b2-3c5f-4a8d-b0e1-2f6c7a9d8b3e",
      "caption": "Reason 1"
    }
  ],
  "captionSize": "medium"
}

Responses

200

The composited slide media.

Media typeapplication/json

object

slides

required

Array<object>

object

index

integer

mediaId

string format: uuid

Example^generated

{
  "slides": [
    {
      "index": 1,
      "mediaId": "2489E9AD-2EE2-8E00-8EC9-32D5F69181C0"
    }
  ]
}

400

The request body failed validation.

Media typeapplication/json

object

code

required

A stable, machine-readable error code to branch on.

string

message

required

A human-readable description.

string

details

Optional structured detail (for example Zod validation issues).

Example

{
  "code": "invalid_request",
  "message": "The request payload is invalid.",
  "details": [
    {
      "path": [
        "slideCount"
      ],
      "message": "Number must be greater than or equal to 3"
    }
  ]
}

401

The API key is missing or invalid.

Media typeapplication/json

object

code

required

A stable, machine-readable error code to branch on.

string

message

required

A human-readable description.

string

details

Optional structured detail (for example Zod validation issues).

Examples

{
  "code": "missing_api_key",
  "message": "A Bearer API key is required."
}

{
  "code": "invalid_api_key",
  "message": "The API key is invalid."
}