Gravekeeper informs users that a repo is abandoned, commenting on new PRs and Issues.
Example/test repository: https://github.com/caarlos0-graveyard/grave (check PRs and Issues).
It is a simple endpoint running on AWS Lambda that comments on new issues and new pull requests.
It is managed with apex/up.
To use it, add this url to your repository (or even organization) webhooks. Set it up like this:
It will leave a comment on new pull requests and new issues:
