Test page speed in controlled conditions
Calibre runs scheduled and on-demand browser tests, so you always know exactly what changed and why.
Dashboard
See how every page performs over time
Every metric charted over time, with each deploy marked.
Spot regressions the moment they deploy
Deploy markers on every chart show exactly which release changed performance.
Learn about Pulse →Any device, network or location
Test from 17 locations on 12+ emulated devices, at any network speed from 2G to cable, on any schedule.
Learn about Test Profiles →Analyse
Diagnose exactly what makes pages slow
Render timelines, request waterfalls, Lighthouse audits and third-party costs in every test.
Watch your page load frame by frame
Replay how your page renders, frame by frame and on video. See what visitors see, and when.
Learn about Snapshots →Get targeted advice for every Web Vital
Lighthouse audits for Performance, Accessibility, SEO and Best Practices, filtered by the metric they affect.
Learn about Audits →Find the scripts blocking your main thread
See every long JavaScript task, which script caused it, and how much blocking time it adds. Filter by first or third party.
Learn about Long Tasks →See what third parties cost you
The size and run time of every external service on the page, so you know what to keep, fix or remove.
Learn about Third Parties →Budgets & Alerts
Stop regressions before they reach users
Set a budget for any metric, and get told when it slips.
Budgets for any metric
Core Web Vitals, JavaScript size, third-party weight, or hundreds of other metrics.
Learn about Budgets →Alerts in Slack, email or webhook
Alerts go where your team already works, and Zapier connects thousands more services.
Learn about Integrations →Enforce budgets in pull requests
Fail pull request checks automatically when a budget is exceeded, before the change merges.
Learn about PR Reviews →Automate
Make speed part of every release
Test pull requests, check every deploy, and run tests on demand from the CLI or API.
Performance reviews in every pull request
Compare a branch against production, with Web Vitals, asset changes and budget status posted to the pull request.
Learn about PR Reviews →Automate with the CLI and Node.js API
Create tests, export metrics, manage sites and track deploys from your terminal or code.
Learn about the CLI & API →Test authenticated and private sites
Test logged-in pages and staging sites with form login, cookies or custom headers.
Learn about Authentication →Run one-off tests for any URL
A full report for any page, to share with stakeholders or run from CI.
Learn about Single Page Tests →“Calibre delivers the substance behind the statistics. They know the actionability of performance measurement is paramount.”
Calibre Synthetic is built for you
Synthetic is included on every plan. Test from 17 locations, on any schedule, with full diagnostics on every run.
