Calibre
Web performance monitoring platform for Core Web Vitals, page speed, and real-user analytics
About Calibre
Calibre is an end-to-end web performance monitoring and analytics platform that combines synthetic testing with real-user data from Chrome User Experience Report (CrUX). It enables teams to track Core Web Vitals, run Google Lighthouse audits, set performance budgets, and catch speed regressions before they reach production through GitHub Pull Request Reviews. With testing infrastructure across 17 global locations, Calibre provides a comprehensive view of how websites perform for users worldwide. The platform is designed for collaborative use across entire organizations. Teams can simulate different devices, connection speeds, and locations using Test Profiles, monitor unlimited sites and URLs on any plan, and get automated insights delivered via email reports. Third-party tracking identifies external scripts that slow down pages, while the AI-powered test verification engine automatically re-tests anomalous results to reduce false positives. Calibre integrates with developer workflows through its CLI, Node.js API, webhooks, and native Vercel and Netlify integrations for automatic deploy tracking. All data is encrypted at rest, retained for the lifetime of your account, and the platform maintains 99.91% uptime with full GDPR compliance.
Pros & Cons
Pros
- Combines synthetic testing and real-user CrUX data in a single platform for comprehensive insights
- GitHub Pull Request Reviews catch performance regressions before they reach production
- Unlimited sites and URLs on all plans — no per-site pricing surprises
- AI-powered test verification reduces false positives and noise in results
- 17 global test locations provide accurate worldwide performance perspective
- No tracking scripts required for real-user monitoring via CrUX integration
Cons
- No free tier — starts at \u002475/month which may be steep for individual developers
- Large price jump from Team (\u0024150/mo) to Company (\u00241,500/mo) with no intermediate option
- Real-user monitoring relies on CrUX data which only covers Chrome users
- 14-day trial may not provide enough data for a thorough evaluation
- Additional test packs cost \u002460 each, which can add up for high-volume testing needs
Key Features
Core Web Vitals Monitoring
Track CWV metrics using real-user CrUX data without installing any tracking scripts
Synthetic Testing
Run automated performance tests across 17 global locations with configurable devices and connection speeds
Pull Request Reviews
Assess speed impact of code changes directly in GitHub PRs before merging to production
Google Lighthouse Built-in
Run industry-standard Lighthouse audits with accessibility, SEO, and performance scoring
Performance Budgets
Set trackable speed goals with automatic alerts when thresholds are exceeded
Third-Party Tracking
Identify how external scripts and tools impact site performance and find alternatives
AI Test Verification
AI-powered engine automatically re-tests anomalous results to reduce false positives
Deploy Tracking
Add deployment markers to performance charts to correlate releases with speed changes
Pages Leaderboard
Rank pages by performance and benchmark against competitors
CLI & Node.js API
Developer-friendly command line interface and npm package for automation and CI/CD integration
Unlimited Data Retention
Historical performance data retained for the lifetime of your account
Slack & Zapier Integration
Get instant alerts in Slack and connect to thousands of apps via Zapier
Pricing
- 5,000 synthetic tests monthly
- 3 included seats
- Unlimited sites and URLs
- Real-user monitoring with CrUX
- 1 team
- Google SSO
- All platform features
- 15,000 synthetic tests monthly
- 10 included seats
- Unlimited sites and URLs
- Real-user monitoring with CrUX
- Unlimited teams
- Google SSO
- All platform features
- 50,000 synthetic tests monthly
- 50 included seats
- Unlimited sites and teams
- Real-user monitoring with CrUX
- SAML & Google SSO
- Invoice payment
- High priority support
Best For
CI/CD Performance Gates
Use Pull Request Reviews to catch speed regressions before merging code to production
Core Web Vitals Optimization
Monitor real-user CWV scores to improve search rankings and user experience
Agency Multi-Site Monitoring
Track unlimited client sites with team-based organization and automated reporting
Third-Party Script Auditing
Identify external scripts slowing down pages and measure their performance impact
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