# Choose the returned file format in image creation requests

August 27, 2026

Image creation requests can now include `format` in the request body. This parameter selects the file extension included in the returned URL; it does not change the stored image definition.

*   Set `format` to `png`, `jpg`, `webp`, or `pdf` for an HTML/CSS image, URL screenshot, saved-template image, or image batch.
*   Raster images are rendered and stored as PNGs. JPG and WebP URLs convert that stored PNG when requested.
*   PDFs are rendered and saved separately when a PDF URL is requested.
*   The same image ID can still be requested later with a different supported extension.
*   Batch requests can set `format` in `default_options` or override it in an individual variation.
*   When omitted, the API returns its default extensionless URL, which renders as PNG.

The official clients now expose the body parameter and apply it to generated signed URL paths:

*   [.NET client v0.12.0](https://github.com/htmlcsstoimage/dotnet-client) with `RenderImageFormat.PDF` support.
*   [TypeScript client v0.9.0](https://github.com/htmlcsstoimage/ts-client).
*   [Ruby client v0.3.0](https://github.com/htmlcsstoimage/ruby-client).

[Read the `format` parameter documentation](/parameters/format/) or compare output types in the [file formats guide](/guides/styling/file-formats/).

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