maltoe

ChromicPDF - PDF generator

Hello!

Came here to announce ChromicPDF, a pet project PDF generator I’ve been working on for the past few months. Why another PDF generator, you may be asking? Because it was fun to implement a client for (small parts of) the Chrome DevTools Protocol in Elixir.

That’s basically Chromic’s main feature, it can talk to Chrome without the need for puppeteer / a NodeJS at runtime. It launches Chrome, spawns a number of targets that it keeps around, and to print a PDF instructs them to navigate to a URL. In sum, this makes for relatively performant PDF generation flow.

For good measure, I threw in a PDF/A converter using Ghostscript, capable of creating veraPDF-test-passing PDF/A-3b files - obviously inspired by a project where we needed to generate invoice PDFs for long-term storage.

Would be super interested in any opinion you might have! It’s not (yet) on hex.pm, will wait a bit to see if people are interested. Documentation can be found in the README and, oddly, in the Supervisor module.

cheers,
Malte

Also kudos to my employer for letting us work on pet projects

63 comments

#protocols #library #pdf-generator #chromeremoteinterface

31 11567 63

2026-01-09 13:45:04 UTC

First Post!

dino

Hi maltoe,

This looks like an interesting project, kudos on building it!

I’ve got some feedback after reading the project’s README.
When calling the ChromicPDF.print_to_pdfa function you’re providing a map in the print_to_pdf argument, however the specific map keys are in camel case while in Elixir I think it’s more standard/common to use snake case, so for example, you’d use:

print_to_pdf: %{
    # Margins are in given inches
    margin_top: 0.393701,
    margin_left: 0.787402,
    margin_right: 0.787402,
    margin_bottom: 1.1811,
   ...
}

instead of the more javascript-like one in the example:

print_to_pdf: %{
    # Margins are in given inches
    marginTop: 0.393701,
    marginLeft: 0.787402,
    marginRight: 0.787402,
    marginBottom: 1.1811,
    ...
}

This might just be nitpicking but I thought I should let you know! Congrats once again in building this

Post #1

Most Liked

maltoe

Just released version 1.0

See the Changelog for recent additions and changes.

Thanks to everyone who took interest into this little project of mine!

Post #25

egze

There is for example PrawnPDF in Ruby GitHub - prawnpdf/prawn: Fast, Nimble PDF Writer for Ruby · GitHub and they do it without a browser or other libs. I always wondered why there is nothing like this in Elixir.

Post #5

Phillipp

Have not read the code nor do I know about the Chrome api, but maybe those options will be passed directly to the API and he just wanted to avoid manually converting from snake case to camel case.
If that is the case, I personally would leave it as it is as it follows the API and people who are familiar with the API would have an easier time working with it. However, if the goal is to completely abstract that, then having them in snake case would be better.

It depends on the viewpoint.

Post #2