It takes the list of .gitignore files from the repository and makes it easily available for search and concatenates multiple gitignore files into one. This can be specially useful when starting a new project.
Its kept up to date with the Github repository (in the footer you can see the commit hash that its using).
Source code: https://codeberg.org/0x00cl/guitignore (Its just an HTML file with the gitignore submodule)