macOS Preview sometimes 'forgets' about annotations that were added to a PDF file. This can be particularly frustrating after providing feedback on a draft for many hours, just to loose the precious annotations when closing and re-opening the file.
This tool attempts to fix the annotations based on a technique described by 'thorimur'.
You can either use the command line app or try the web app hosted on GitHub Pages.
Thanks to WebAssembly, you can also use this tool from the browser here.
The web app runs entirely in the browser and the PDF is never sent anywhere.
The source code can be found under web-app directory of this repository.
You need to have a working rust toolchain installed.
Then just run the program using cargo:
~ cargo run -- my_messed_up.pdf fixed.pdf
# ...
recovered 188 annotations