---
title: "Apply watermark"
method: POST
path: "/watermark/apply"
tags: ["watermark"]
---

# Apply watermark

`POST /watermark/apply`

Apply a Perth v2 watermark to an audio, image, or video file. The media type is automatically detected from the file content. Processing is asynchronous unless the `Prefer: wait` header is supplied.

## Headers

- `Authorization` string, required
- `Prefer` 'wait'

## Request body

- WatermarkApplyRequest
  - `url` string, uri, required — Public HTTPS URL to the audio, image, or video source.
  - `strength` number, double — Watermark strength for image/video. Ignored for audio.
  - `custom_message` string — Message to embed in image/video. Ignored for audio.

## Response `200`

Watermark job created

- WatermarkApplyResponse
  - `success` boolean, required
  - `item` WatermarkApplyItem, required
    - `uuid` string, required
    - `media_type` 'audio' | 'image' | 'video', required — Detected media type of the source file.
    - `operation_type` 'apply', required
    - `status` 'pending' | 'processing' | 'completed' | 'failed', required
    - `model_version` 'perth_v2', required
    - `source_media_url` string, uri, required
    - `watermarked_media` string, uri, nullable — Signed output URL when processing is complete.
    - `metrics` WatermarkApplyMetrics — Apply metadata for image/video. Audio apply metrics are null.
      - `strength` number, double
      - `custom_message` string
      - `message_bits_length` integer, nullable
    - `created_at` string, date-time, required
    - `updated_at` string, date-time, required

## Changes

- **2026-08-22** `e93597a6b425` — 3 warning
  - the `custom_message` request property's maxLength was set to `64`
  - the `strength` request property's max was set to `1.00`
  - the `strength` request property's min was set to `0.00`
- **2026-07-26** `5e92bebbaf1f` — 1 breaking, 14 info
  - the `item/metrics` response's property type/format changed from ``/`` to `object`/`` for status `200`
  - added the optional property `item/metrics/custom_message` to the response with the `200` status
  - added the optional property `item/metrics/message_bits_length` to the response with the `200` status
  - added the optional property `item/metrics/strength` to the response with the `200` status
  - …11 more

[Change history](https://skmtc.dev/resemble/apis/api-reference/changes/watermark/apply/post.md)

---

[API](https://skmtc.dev/resemble/apis/api-reference.md) · [All operations](https://skmtc.dev/resemble/apis/api-reference/llms.txt) · [OpenAPI document](https://skmtc-service-production.skmtc.workers.dev/v1/apis/resemble/api-reference/revisions/e93597a6b425/schema)