What Does 99.9% Uptime Really Mean? A Practical Guide to SLAs and Downtime Budgets
Translate uptime percentages into downtime, distinguish SLIs, SLOs, and SLAs, and learn how to measure partial outages and error budgets fairly.
The Testable Blog
Monitoring, reliability, and testing.
Practical articles on keeping websites and APIs available, correct, and fast—plus the testing practices that support reliable systems.
From the blog
Latest posts
Cron Job Monitoring: How to Detect Silent Failures in Background Jobs and Workers
Learn how heartbeat monitoring detects missed cron jobs, stalled workers, long runtimes, and unhealthy service clusters without exposing an inbound endpoint.
Multi-Region Monitoring: How Often Should You Check—and When Should You Alert?
Learn how to choose monitoring regions, check frequency, timeouts, retries, confirmation checks, and alert thresholds without creating noisy incidents.
Website Performance Monitoring: Core Web Vitals, Page Load Time, and Performance Regressions
Learn which website performance metrics to monitor, how lab and field data differ, and how to catch regressions with baselines, budgets, and scheduled checks.
How to Turn Playwright Tests into Reliable Production Monitors
Learn how to adapt Playwright tests for continuous production monitoring with safe accounts, resilient locators, meaningful assertions, controlled retries, and useful failure evidence.
What Is Synthetic Monitoring? Uptime Monitoring vs. RUM vs. APM
Learn how synthetic monitoring, uptime monitoring, real user monitoring, and application performance monitoring differ—and how to combine them effectively.
API Monitoring Best Practices: Status Codes, Response Data, Authentication, and Workflows
A practical guide to monitoring API availability, correctness, performance, authentication, rate limits, and multi-step business workflows.
Website Monitoring Checklist: What to Monitor Beyond a 200 OK
A practical website monitoring checklist covering availability, content, performance, critical user journeys, dependencies, certificates, regions, and alerting.
Playwright Test Tags Guide
Playwright Test is a powerful, well thought out test framework that helps you streamline and enhance your testing workflows. The Playwright team has carefully thought about various workflows related to software development and testing which makes it one of the best options out there. In this post we'll go over it's useful tags feature that make tests more organized, flexible, and efficient.
Playwright Test Annotations Guide
Playwright Test is a powerful, well thought out test framework that helps you streamline and enhance your testing workflows. The Playwright team has carefully thought about various workflows related to software development and testing which makes it one of the best options out there. In this post we'll go over it's useful annotations feature that make tests more organized, flexible, and efficient.