A serverless implementation of ActivityPub

Mumble is a serverless implementation of ActivityPub that can communicate with other compliant servers such as Mastodon.


  • Basic features of ActivityPub
    • Publish post (mumble)
      • Only public post (mumbling) so far
      • Optional attachments
    • Deliver mumblings to your followers
  • Communication with Mastodon
    • Your Mumble account may be reached and followed by Mastodon users.
  • Built with serverless technologies on AWS
    • You can start it with almost zero cost and scale it as you gain traffic!
  • Built-in viewer app for guests
    • You can promote your Mumble account by sharing your profile URL.
    • Guests can search your mumblings with free-form texts.

More features are coming!

How to get started

Mumble itself is not a cloud service but a software package including the recipe for the AWS infrastructure. However, you can easily deploy it to your AWS account if you have some experience with AWS and AWS Cloud Development Kt (CDK). Please refer to the GitHub repository for how to deploy Mumble.

Viewer app

Any guests can view your profile and public mumblings on the built-in viewer app. Include its URL in your social media profile to promote your Mumble account. Guests can also search your mumblings with free-form texts on the search page powered by FlechasDB, and OpenAI's embeddings.

Here is a screenshot of Kikuo's profile page ( viewer app


To mumble on Mumble, you need a client app. There is an official client MumbleBee.


I often write down thoughts and findings in short texts (mumblings) while I am working. For that purpose, I used to use Microsoft Teams, Slack, Discord, or whatever the workplace provided. These mumblings often turned out useful for my colleagues and me later. Now, as a freelance, I started to want to have my own place to publicly write down these mumblings. Twitter could have been a good place, but I felt somehow it was not the right place for me. During the recent turmoil around Twitter, Mastodon, a decentralized social network, caught my attention, and I was attracted to ActivityPub behind Mastodon. Since hosting Mastodon required a traditional setup of servers that was not the way I was eager to pursue, I decided to implement a serverless version of ActivityPub on AWS.

GitHub repository

Please refer to the GitHub repository ( for how to deploy Mumble and more details.