What does it cost to convert WebP to PNG?

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

How large can the WebP 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 / WebP to PNG

Convert WebP to PNG

To convert WebP to PNG, send one POST to /v1/image-convert with the WebP source and "format": "png" 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 WebP to PNG run of image-convert.

Request

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

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

Response

200 OK
payment-response: <base64 settlement receipt>

{
  "source_url": "https://grist.tools/samples/images/pair-note.webp",
  "source_format": "webp",
  "format": "png",
  "mime_type": "image/png",
  "width": 556,
  "height": 100,
  "bytes": 1021,
  "image_base64": "iVBORw0KGgoAAAANSUhEUgAAAiwAAABkCAIAAAAqgfyWAAAACXBIWXMAAAPoAAAD..."
}

Source file: images/pair-note.webp, 248 bytes. Lossless WebP of the same 556x100 raster as ocr-scan.png: two uppercase lines drawn from a hand-written 5x7 bitmap font, SAMPLE SCAN FOR OCR and SECOND LINE 2026. The request sets quality to 80. The recorded run returned 1,021 bytes of PNG, 4.1 times the source size, with an image of 556x100 pixels. Decoded, the PNG in image_base64 opens with 89 50 4E 47 0D 0A 1A 0A 00 00 00 0D (ASCII PNG).

In the sample itself, the RIFF header counts 240 bytes after itself and the one chunk is a lossless VP8L bitstream of 227 bytes for 556 by 100 pixels, with the alpha hint clear. In the returned PNG: its IHDR chunk declares 556 by 100 pixels, 8-bit truecolour RGB and no interlacing. The next chunk is pHYs.

03Format notes

WebP as a source

WebP can hold lossy or lossless imagery, alpha and animation inside a RIFF container. Grist checks for RIFF at byte zero and WEBP at byte eight; the second test matters because WAV and AVI files also open with RIFF and differ only in that form type. image-convert and ocr-image-to-text each perform the check themselves before any decoder runs. For conversion, sharp opens the file with animated decoding off, so an animated WebP contributes only its first frame, and the header dimensions are compared with the shared pixel budget beforehand. The output does not record whether the source was lossy or lossless: image-convert re-encodes the decoded pixels and drops metadata. A lossless WebP therefore hands exact pixel values to the target encoder, whereas a lossy one passes its own artefacts along.

PNG as a target

PNG output is lossless, so image-convert ignores the quality value when PNG is requested. Its encoder options are pinned: the maximum zlib compression level, a fixed effort, adaptive filtering off, palette quantisation off and no interlacing, so identical pixels always deflate to identical bytes. Dimensions are kept and reported in the response, and metadata is stripped. Vector input takes a separate service: svg-to-png renders the document at a caller-set density, which drives the natural raster size, and an optional width or height fits the render inside that box with the lanczos3 kernel, keeping the aspect ratio, before the same pinned PNG options apply. video-thumbnail writes PNG by default through ffmpeg's png encoder; when a width is requested, the height follows the aspect ratio and is rounded to an even number.

Note: An animated WebP is converted from its first frame only.

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 WebP to PNG?: $0.003 per call, paid in USDC on Base via x402.
How large can the WebP 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.