Calibre for Developers
Performance data in your terminal, CI, and PRs
Powerful tools and APIs that let you automate testing, extract data, and integrate performance checks into your CI/CD pipeline, without building infrastructure from scratch.
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Why Developers love Calibre
Connect GitHub or CI/CD pipeline for automated performance checks
Powerful CLI and API for custom workflows and data retrieval
Skip building custom monitoring infrastructure
Block specific hosts and third parties in tests
Test pages behind authentication
Technical support from a team of performance experts
“Calibre delivers the substance behind the statistics. They know the actionability of performance measurement is paramount.”
Synthetic Testing
Focus on code, not infrastructure
Let Calibre’s synthetic testing infrastructure handle the monitoring while you build your product.
Stop maintaining your own testing infrastructure
Our synthetic testing platform runs Lighthouse on Chrome across a global network of test agents. Tests are automatically verified to filter out anomalies.
Learn about Synthetic Testing →Get performance feedback in every pull request
Calibre’s GitHub integration posts performance analysis directly into your PRs. See how changes affect LCP, CLS, and TBT before you merge.
Learn about PR Reviews →Authenticate & Automate
Test what your users actually see
Monitor logged-in pages, staging environments, and private applications. Integrate performance checks into your CI/CD pipeline.
Test pages behind authentication
Configure form-based login, cookie auth, or custom headers. Test the pages your users actually interact with, not just the public-facing shell.
Learn about Authentication →Automate
Automate with CLI and Node.js API
Create tests, export metrics, manage sites and track deploys, all from your terminal or code.
Performance checks in CI/CD
Run tests automatically on every deploy or pull request. Compare work-in-progress branches against production before merging.
Learn about GitHub Actions →Deploy tracking
Connect GitHub and Calibre marks every production deploy on your charts automatically, or create deploys from the CLI or API. Compare each release with the one before it.
Learn about deploy tracking →Full CLI for any workflow
The calibre npm package lets you run one-off tests, manage sites, export metrics, and track deploys from your terminal or CI pipelines.
Learn about the CLI →Node.js API
Programmatic access to all monitoring data: create and manage custom monitoring, collect data from synthetic tests, performance budgets, and CrUX metrics.
NPM package and API docs →Questions from developers
How do I add performance checks to CI/CD?
Use the Calibre GitHub Action or the calibre CLI in any CI system to run tests on every deploy or pull request. Pull request reviews test a preview deployment from Vercel, Netlify, Render or any public URL and post the performance impact on the pull request.
Can Calibre test pages behind a login?
Yes. Calibre supports single and multi-step form login, basic authentication, and custom cookies and headers. Authentication runs on every Page in a Site. Two-factor authentication is not supported.
What APIs does Calibre have?
Calibre has a CLI (the calibre npm package, where every command supports --json), a Node.js API, a GraphQL API and an HTTP Site API. Use them to create tests, manage Sites, track deploys and export metrics.
How does Calibre run its tests?
Calibre runs Lighthouse in Chrome on a global network of test agents, from the test location you choose for each Site. Test Profiles set the emulated device, connection speed, cookies and headers, and can block ads, JavaScript or specific third parties. Tests are automatically verified to filter out anomalies.
Does Calibre measure real users as well as synthetic tests?
Yes. Calibre combines synthetic Lighthouse tests with Real User Monitoring and Google’s Chrome User Experience Report (CrUX) data, so you can compare lab results with what visitors experience.
Need help to dial in your new speed system?
Our friendly, knowledgeable team will help you establish a system that works efficiently or answer any questions. We’re here to support you in your web performance journey. Contact support.
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