FreeLeaf: A free self-hosted alternative to Overleaf

How it all started ...

This story started when we wrote the MIDOG 2025 challenge paper. The challenge, hosted for the third time, was a huge success, with many people from all over the world participating. After the workshop, I wanted to write the challenge report. And here is where my troubles started: I am not part of one of those universities that bought Overleaf for all of their staff. Yes, it's a nice tool, especially for collaboration, but it's also expensive, especially if you have to pay out of your own pocket.

But since this paper was really important to me and I wanted to really have a good collaboration with all co-authors, I said to myself: Ok, then you gotta pay, what you gotta pay, and went for the paid tier. It's only after I sent out the link to the co-authors that I realized that I wasn't even able to share will all of them, since there is a new policy in that requires me to have an even higher paid tier if I have more collaborators on that project.

That was really too much for me. I already considered the service quite expensive, but paying 30€ per month? That's four times what I pay for my web server that's hosting deepmicroscopy.org. It was just enough for me to make a decision.

Enter: Agentic coding

We are now in the day and age of agentic coding, and while it would take a while before multiple successful open source clones of paid subscription models (->looking at you, Adobe) made the headlines, I thought I'd give it a try and see how much effort it would be to create such a clone for myself - and for joint authoring of LateX documents.

I tried Claude Code for this, and was surprised of the progress they made recently. Of course, it creates bugs, but not on a level exceeding my own coding skills. And yes, the outcome was not really usable professionally in the beginning, but a good start.

Now, 160 commits and lots of feedback from me, my PhDs and students later, the software is quite good. And for the most part better than the original, in my (biased) view.

Building features over features

What's really amazing when you now suddenly have your own clone of a software that you regularly use, you realize: Hey, I have some ideas of things that are missing. That would make my life just better. So, over time, I added the following things, that overleaf did not have:

Anonymous, no-account contribution via share links — Overleaf requires signing up to edit
ORCID sign-in as a first-class login method, alongside passwordless magic-link email auth
Automatic version history (auto-commit on compile or after idle time) built in, not a separate paid "history" tier
Context-aware BibTeX paste/drop — pasting or dropping BibTeX content adds it to the library instead of inserting raw text
Package wizard — detects commands like \ac/\acp and proactively suggests adding the matching package
Mobile-first reviewing workspace — PDF-default view, tab-based editor/PDF/comments switching, built for phones specifically
Personal, private project collections — organize your own dashboard view (e.g. by conference) without affecting how co-authors see the same shared projects

Try and see for yourself

FreeLeaf is open source. You can find it here: https://github.com/DeepMicroscopy/FreeLeaf