Every render targets one output format. Pick based on where the file will be used.

PDF

Pure vector, print-ready.
Embedded fonts and ICC-safe colors.
Multi-page with auto-pagination.
Best for invoices, contracts, certificates, reports.

PNG

Lossless raster with alpha channel.
Scale with the scale parameter — any number from 0.1 to 4. Anything above 1.5x costs double the credits.
Best for social posts, thumbnails, previews.

WebP

~30% smaller than PNG at similar quality.
Alpha channel supported.
Best for web delivery, email hero images.

How to ask for one

The format is the format field — "pdf", "png" or "webp" — and the resolution is scale. Those two are the whole contract — for a cheap in-app preview, ask for png at a scale below 1, and for the download ask for pdf. action is a legacy alias that only picks a format: on /v1/render/html it is refused outright with 400 unknown_fields. Send format.

Video (MP4) exports

The render API returns PDF, PNG and WebP only. MP4 is not available over the API.