Image Convert API

Convert WebP to PNG or PNG to WebP server-side — with optional background fill, quality control, and full alpha-channel support.

Get your API token

Create an account and subscribe ($9/month) to start using the API.

Create account Sign in

Endpoint

POST /api/image-convert

Send the image as a multipart/form-data upload. The response is the converted image binary.

Limits

Max file size: 100 MB
Max image dimensions: 10 000 × 10 000 px
Accepted input formats: WebP, PNG

Authentication

Include your API token in every request:

Query parameter: ?token=YOUR_TOKEN
Header: Authorization: Bearer YOUR_TOKEN

Parameters

Parameter	Required	Values	Description
`file`	Yes	WebP or PNG file	The image to convert. Must be a valid `.webp` or `.png` file.
`to`	Yes	`png`, `webp`	Target output format.
`bg`	No	`transparent` (default), `white`, `black`, `#rrggbb`	Background to fill behind transparent areas. Use a hex colour (e.g. `#ff0000`) for a custom colour. Ignored if the image has no transparency.
`quality`	No	`default` (default), `small`, `medium`, `best`	WebP output quality. `small` = 50, `medium` = 75, `best` = 92. Only applies when `to=webp`; PNG is always lossless.

Response

On success the API returns the converted image as binary with the appropriate Content-Type header (image/png or image/webp) and a Content-Disposition: attachment header containing the output filename.

HTTP/1.1 200 OK
Content-Type: image/png
Content-Disposition: attachment; filename="photo.png"

<binary image data>

Error responses are JSON: {"error": "message"}.

Example Requests

WebP → PNG (transparent background preserved)

curl -X POST https://abesttools.com/api/image-convert \
  -H "Authorization: Bearer YOUR_TOKEN" \
  -F "[email protected]" \
  -F "to=png" \
  -o photo.png

PNG → WebP with white background and medium quality

curl -X POST https://abesttools.com/api/image-convert \
  -H "Authorization: Bearer YOUR_TOKEN" \
  -F "[email protected]" \
  -F "to=webp" \
  -F "bg=white" \
  -F "quality=medium" \
  -o photo.webp

WebP → PNG with custom background colour

curl -X POST https://abesttools.com/api/image-convert \
  -H "Authorization: Bearer YOUR_TOKEN" \
  -F "[email protected]" \
  -F "to=png" \
  -F "bg=#f5f5f5" \
  -o logo.png

Error Responses

HTTP Status	Reason
`401`	Missing or invalid API token.
`403`	No active subscription.
`422`	Missing file, unsupported format, file > 100 MB, or dimensions > 10 000×10 000 px.
`500`	GD extension or WebP support not available on the server.