Duplicate detection

Control how far back the API looks for an identical image before rendering a new one.

When you create an HTML/CSS image or URL screenshot with POST /v1/image, the API can look for an identical image created within a configurable time window. MCP-created HTML/CSS images and URL screenshots use the same behavior.

If a matching image is found in your organization, the response returns its existing id and url. The request consumes no image credits because a new image is not created.

The rendered content and image parameters must match exactly. A different character or parameter value creates a different image. The dedupe_duration_s value itself is excluded from this comparison, so you can change the lookback window without changing what counts as an identical image.

Set dedupe_duration_s to the number of seconds the API should look back. Set it to 0 to disable deduplication for that request.

{
  "html": "<h1>Monthly report</h1>",
  "css": "h1 { color: navy; }",
  "dedupe_duration_s": 3600
}

The value is request-only: it is not saved on the image and does not become the default for later requests. Every request can use a different lookback window.

When dedupe_duration_s is omitted, URL screenshots default to 0 seconds because URL content is expected to change more often. HTML/CSS requests use the default for your plan:

These explicit-value limits apply to both HTML/CSS images and URL screenshots. For example, a Pro URL request can opt into any lookback from 0 through 180 days even though its omitted default is 0.

The configurable lookback applies to HTML/CSS images and URL screenshots created through the standard single-image POST endpoint or the MCP image-creation tools.

It does not apply to:

• Templated images, which are already identified by their template ID and values.
• Signed create-and-render URL images, which already use content-based IDs.
• Image batch requests.

See the dedupe_duration_s parameter reference for request examples.