What does it cost to convert PNG to WebP?

$0.003 per call, paid in USDC on Base via x402.

How large can the PNG file be?

Up to 25 MB (26,214,400 bytes). Past a limit the call answers too_large (413).

What happens if the conversion fails?

The tool answers with a typed JSON error from the errors table. Payment is settled only after the tool has produced its result; a call that fails inside the tool is never settled.

catalogue / tools / Images / PNG to WebP

Convert PNG to WebP

To convert PNG to WebP, send one POST to /v1/image-convert with the PNG source and "format": "webp" in the body. Each call costs $0.003 in USDC on Base via x402, with no account and no API key. The source file can be up to 25 MB.

Endpoint: POST /v1/image-convert
Price: $0.003 per call
Service: image-convert
Docs: /docs/image-convert

01Limits

Limit	Value
Largest source file	25 MB (26,214,400 bytes)
Timeout	60 s
Source formats	AVIF, GIF, JPEG, PNG, SVG, TIFF, WebP
Output formats	JPEG, PNG, WebP
Option quality	default 80

02Example

A real PNG to WebP run of image-convert.

Request

POST /v1/image-convert
content-type: application/json
payment-signature: <base64 x402 payload>

{
  "url": "https://grist.tools/samples/images/convert-gradient.png",
  "quality": 80,
  "format": "webp"
}

Response

200 OK
payment-response: <base64 settlement receipt>

{
  "source_url": "https://grist.tools/samples/images/convert-gradient.png",
  "source_format": "png",
  "format": "webp",
  "mime_type": "image/webp",
  "width": 32,
  "height": 32,
  "bytes": 156,
  "image_base64": "UklGRpQAAABXRUJQVlA4IIgAAAAQBQCdASogACAALk02m02hJCQkBABMS2AE6ZiX..."
}

Source file: images/convert-gradient.png, 1.8 KB (1,817 bytes). 32x32 PNG of a smooth two-axis gradient (red rises left to right, green top to bottom), built from raw pixels with the pinned PNG encoder. The request sets quality to 80. The recorded run returned 156 bytes of WebP, 9% of the source size, with an image of 32x32 pixels. Decoded, the WebP in image_base64 opens with 52 49 46 46 94 00 00 00 57 45 42 50 (ASCII RIFF and WEBP).

In the sample itself: its IHDR chunk declares 32 by 32 pixels, 8-bit truecolour RGB and no interlacing. The chunks run IHDR, pHYs, IDAT and IEND. In the returned WebP: the RIFF header counts 148 bytes after itself, and the one chunk is a lossy VP8 bitstream of 136 bytes that starts with a key frame of 32 by 32 pixels.

03Format notes

PNG as a source

Every PNG opens with the eight-byte signature 89 50 4E 47 0D 0A 1A 0A. The format is lossless and can carry an alpha channel. image-convert matches all eight bytes before sharp is loaded, while the OCR detector settles for the first four. Both services then read the dimensions from the header without decoding the raster, and a file whose width times height exceeds the shared decoded-pixel budget is refused at that point. The check exists because a small, highly compressible PNG, such as a solid colour or a decompression bomb, can inflate to an enormous raster, and Tesseract's cost grows with the pixel count. Since PNG stores exact pixel values, a PNG source contributes no compression noise of its own; any loss in a converted file comes from the lossy target encoder.

WebP as a target

Selecting WebP in image-convert always yields lossy WebP. The pinned options switch off lossless and near-lossless modes and smart subsampling, and fix the encoder effort so the search does not vary between builds; the caller's quality value is the one setting that changes the result. A lossless source such as PNG is therefore re-encoded lossily when WebP is the destination. The pixel grid stays as it was and the response reports width and height. Metadata blocks are removed because sharp is never asked to keep them, and animation is not written: the decoder reads the first frame only. Vector sources reach this encoder through image-convert, which rasterises them at sharp's default density with no density option, so an SVG becomes a WebP at its intrinsic size rather than at a caller-chosen resolution.

04Errors

Code	HTTP
`invalid_input`	`400`
`blocked_target`	`403`
`unreachable_target`	`424`
`upstream_timeout`	`424`
`unsupported_content_type`	`415`
`too_large`	`413`
`unprocessable`	`422`
`internal`	`500`

When each is raised, and what it means for payment: /docs/image-convert.

05Questions

What does it cost to convert PNG to WebP?: $0.003 per call, paid in USDC on Base via x402.
How large can the PNG file be?: Up to 25 MB (26,214,400 bytes). Past a limit the call answers too_large (413).
What happens if the conversion fails?: The tool answers with a typed JSON error from the errors table. Payment is settled only after the tool has produced its result; a call that fails inside the tool is never settled.