How to leave a message for a github.com user

Need help on GitHub usage. I wonder if there is a way to communicate with a github.com user i.e. write the user a message when only username/id is given on their GitHub page? Does GitHub have this social feature?

Although GitHub removed the private messaging feature, there's still an alternative.

GitHub host git repositories. If the user you're willing to communicate with has ever committed some code, there are good chances you may reach your goal. Indeed, within each commit is stored some information about the author of the change or the one who accepted it.

Provided you're really dying to exchange with user user_test

• Display the public activity page of the user: https://github.com/user_test?tab=activity
• Search for an event stating "user_test pushed to [branch] at [repository]". There are usually good chances, they may have pushed one of his own commits. Ensure this is the case by clicking on the "View comparison..." link and make sure the user is listed as one of the committers.
• Clone on your local machine the repository they pushed to: git clone https://github.com/..../repository.git
• Checkout the branch they pushed to: git checkout [branch]
• Display the latest commits: git log -50

As a committer/author, an email should be displayed along with the commit data.

Note: Every warning related to unsolicited email should apply there. Do not spam.

This method was working as of June 2021

1. Copy and paste the next line into your browser (feel free to bookmark it): https://api.github.com/users/xxxxxxx/events/public
2. Find the GitHub username for which you want the email. Replace the xxxxxxx in the URL with the person's GitHub username. Hit Enter.
3. Press Ctrl+F and search for “email”.

As suggested by qbolec, the above steps can be done by using this snippet:

<input id=username type="text" placeholder="github username or repo link">
<button onclick="fetch(`https://api.github.com/users/${username.value.replace(/^.*com[/]([^/]*).*$/,'$1')}/events/public`).then(e=> e.json()).then(e => [...new Set([].concat.apply([],e.filter(x => x.type==='PushEvent').map(x => x.payload.commits.map(c => c.author.email)))).values()]).then(x => results.innerText = x)">GO</button>
<div id=results></div>

Source: Matthew Ferree @ Sourcecon