Skip to content


Site speed monitoring without the hassle.

👋🏻 Hello there

We are ♠️ Calibre: an (intentionally) small company building a web performance platform to help create faster, more equitable internet.

Our team has a long history of community organising, from open source contributions and facilitation (for example, projects like Ruby on Rails, Bower and Node.js) to organising dozens of international events (such as JSConf and CSSConf).

We feel at home when helping people, and GitHub is one of the places where we do it.

💓 Giving back to the ecosystem

Because we believe in paying it forward, we actively work on building tools to benefit people and teams interested in improving web performance and user experience. Here are our favourite projects:

  • Calibre CLI: a command-line interface and Node.js API for Calibre data and actions.
  • Image Actions: a GitHub Action that automatically optimises your images in pull requests.
  • React Live Chat Loader: an npm module that mitigates the negative performance impact of chat tools.

We also contribute to existing tools, such as Google Lighthouse or Chrome HAR. Beyond GitHub, we run 📬 a fortnightly page speed newsletter and regularly publish 📝 high-quality content about speed.

🙌🏻 Want to join us?

We’re currently hiring developers—if you value a supportive work environment with interesting technical challenges and code ownership, check out 📢 our current open positions for more details! We’d love to get to know you.


  1. cli Public

    Calibre’s Node.js API and Command Line Client (CLI).

    JavaScript 113 16

  2. A Github Action that automatically compresses JPEGs, PNGs and WebPs in Pull Requests.

    TypeScript 1.1k 56

  3. Implement a live chat beacon in your React application without performance regressions.

    TypeScript 372 38

  4. .github Public template

    Community health files and templates for Calibre’s open source and private repositories.