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pdfconversionapi

PSB to WebP API

Send a .psb to /v2/convert/psb/to/webp and get a lossless WebP back in the JSON. The banner sample needs no options: 384 × 128 pixels in 16,340 bytes, about a third of the 47,095-byte 16-bit PNG the same file gives.

Endpoint
POST /v2/convert/psb/to/webp
Accepts
psb
Sample timing
88 ms median of 5 runsHow we measure
Request size
Up to 10 MB on the Free plan or 100 MB on paid plans, all files together

Request and response

Every sample below ran against the API before this page was published. Set PDFCONVERSIONAPI_KEY to your key and run it as is.

curl -sS -X POST \
  https://api.pdfconversionapi.com/v2/convert/psb/to/webp \
  -H "Authorization: Bearer $PDFCONVERSIONAPI_KEY" \
  -F File=@ridge-loop-trail-banner.psb \
  -o response.json

# FileData is base64. Save the first file in converted/,
# or print the JSON error.
if jq -e '.Files' response.json > /dev/null; then
  mkdir -p converted
  name=$(jq -r '.Files[0].FileName' response.json)
  jq -r '.Files[0].FileData' response.json \
    | base64 --decode > "converted/$name"
else
  cat response.json
fi
200 OK88 ms median1 file, 16 KB
{
  "ConversionCost": 1,
  "ConversionTime": 0.088,
  "Files": [
    {
      "FileName": "ridge-loop-trail-banner.webp",
      "FileExt": "webp",
      "FileSize": 16340,
      "FileData": "UklGRsw/AABXRUJQVlA4TL8/…"
    }
  ]
}

Response from our test run on 2026-11-03. ConversionTime shows the median of 5 runs. FileData is shortened here; the real response carries the whole file as base64.

The sample, converted

The same file the code sends. Download the input and the output and compare them yourself.

First page of ridge-loop-trail-banner.webp, rendered by the API
Input
ridge-loop-trail-banner.psb (171 KB)
Output
ridge-loop-trail-banner.webp (16 KB)
Source
A layered trail-map banner we drew for this site: 384 x 128 pixels at 16 bits per channel on an opaque Background layer, with seven layers including a smooth sky gradient and a hidden old route. Written in the large document (PSB) format by our own script from the published file format specification. (CC0-1.0). How it was made
Made by
2026-11-04, API build 9eeeb0640aba

Parameters

Send these as form fields next to the file. Names are case-insensitive. If you set one of the documented options below that we don't support yet, the request fails with a 400 that names it instead of returning a file made without it.

ParameterWhat it does
ImageWidthintegerWidth of the WebP. Needed for documents wider than 16,384 px: a 40,000 px test PSB converted with ImageWidth=16384 and returned 413 without it. 192 gave the banner in 8,434 bytes.Values: 1–20000
ImageHeightintegerHeight of the WebP; the same 16,384 px ceiling applies to tall documents.Values: 1–20000
ScaleProportionsboolean, default truefalse allows a stretched result at the exact width and height.
ScaleIfLargerboolean, default falseWith true, a document already inside the requested size is left alone.
ScaleImageboolean, default truefalse crops from the top-left corner rather than scaling.
ColorSpaceenum, default defaultgray gave 6,632 bytes and monochrome 748 bytes for the banner.Values: default, rgb, gray, monochrome; cmyk returns 400
TransparentColorstringOne exact color becomes clear. #FFFFFF cleared the 295 pixels that are pure white, the core of the label and markers, while their softer edges stayed opaque (17,480 bytes).Values: #RRGGBB, R,G,B or a color name
FileNamestringName of the result without extension; defaults to the upload's.
StoreFileboolean, default falsetrue swaps the base64 data for a link that expires after 3 hours.

What carries over, and what doesn't

Kept

  • Every merged pixel, losslessly: each value equals the 16-bit document rounded to 8 bits
  • The visible layers only; the sample's hidden Old route is not drawn
  • A file smaller than the 16-bit PNG: 16,340 bytes against 47,095

Lost or not yet supported

  • The 16-bit depth. WebP stores 8 bits per channel, so the banner's 2,056 distinct 16-bit colors become 1,421; the sky gradient's 128 rows still get 128 different colors.
  • Layers, the 150 ppi setting and any color profile.
  • Very large sides. Past 16,384 px the request returns 413 instead of being scaled for you.

Limits

  • One PSB per request.
  • Requests up to 10 MB on the Free plan or 100 MB on paid plans, all files and fields together.
  • WebP width and height at most 16,384 px. A 40,000 × 120 PSB returned 413 'WebP images can be at most 16,384 pixels on a side, and this one is 40,000×120'. With ImageWidth=16385 the banner, then 16,385 × 5,462, got the same kind of 413, which also asks for a lower ImageWidth or ImageHeight.
  • 100,000,000 pixels at most after flattening, or 413.
  • 120 seconds per conversion, then 504.
  • Type layers, smart objects and layer effects in PSB files are not tested yet.

Where teams use it

Panoramas and long banners on a web page

Wide artwork kept as PSB can go on a page as WebP. The WebP is a fraction of the size and keeps every pixel of the 8-bit result, so a gallery or landing page can show the real thing.

One web format for every upload

If your site already serves WebP, convert PSB uploads straight to it instead of going through PNG; set ImageWidth at the width your layout uses.

Questions

Can I set a WebP quality?

No. The WebP is always lossless. On this route ImageQuality is not refused, it is ignored: 50 returned the same 16,340 bytes. (The PSD to WebP route refuses any value but 75, because ConvertAPI documents the option there.)

My PSB is wider than 16,384 pixels. What do I send?

Add ImageWidth=16384 or less. A 40,000 × 120 test PSB returned 413 on its own, with a message that names the limit and its 40,000×120 size, and converted to 16,384 × 49 with the width set.

Do I lose color going from 16 to 8 bits?

Each value is rounded to the nearest 8-bit step, and nothing else changes. In one column of the sample's sky, the 30 rows that differ at 16 bits still differ after rounding.

Convert your first PSB file in a minute.