← PDF compressor

Compress a PDF with curl

Make a PDF smaller by downsampling its images. Choose how far: screen (smallest), ebook, printer or prepress. Here is the whole call with curl, with the output it produced when we ran it.

Before you start

An API key. Create a free account; it comes with free tokens every month. Put the key in an environment variable so it stays out of your code: export BLOODWEB_KEY=your_key
curl 7.76 or later (for --fail-with-body, which makes curl stop on an error and still show the reason).
The input file in the same folder: scan.pdf. Use your own; that is the name the code expects.

The code

Save it as pdf-compress.sh and run bash pdf-compress.sh.

curl -sS --fail-with-body \
  -H "Authorization: Bearer $BLOODWEB_KEY" \
  -F file=@scan.pdf \
  -F level=ebook \
  https://bloodweb.net/api/v1/pdf-compress \
  -o smaller.pdf

What you get

Tested 19 October 2026: this exact code ran against our test copy of the API, which runs the same service code as bloodweb.net, and produced this.

It writes smaller.pdf: a PDF, 3 pages, 1 KB.

The PDF compressor output, page 1 — Page 1 of the result.

Change the call

Every option the PDF compressor takes. Add or change them the same way as the ones in the code.

level: screen: images at 72 DPI, smallest. ebook: 150 DPI, good for email. printer: 300 DPI. prepress: 300 DPI, colour kept for print shops. One of: screen, ebook, printer, prepress.
grayscale: Convert everything to shades of grey. Often halves a scanned colour document again.

If it fails

A failed call is not charged. The answer is JSON with an error object; curl stops with an error, and that JSON lands in smaller.pdf instead of the result, so open it as text to read the reason. The usual ones:

401 missing_key or invalid_key: BLOODWEB_KEY is not set in the shell that runs the code, or the key was revoked.
415 unsupported_type: the file is not a type this service reads. The type is read from the file itself, so renaming a file does not change it.
413 file_too_large: the file is over the limit on the service page.
402 insufficient_tokens: the balance does not cover the call. Top up in the dashboard.
429 rate_limited: too many calls at once. Wait the seconds in the Retry-After header and send it again.

Every code and its fix is in the docs.

The PDF compressor page: every option, the limits, and Try it now in your browser.
Getting started: keys, errors and rate limits for all the services.