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“Three nines” uptime sounds reassuring until you do the math. A service can hit 99.9% availability and still be down long enough for users to notice, tickets to pile up, and SLAs to get uncomfortable. The gap between the percentage and the real impact is where confusion starts. This post breaks down what 99.9% uptime […]

A 999 status code usually shows up when a request gets blocked, not when a server crashes. Your site looks fine, but crawlers, bots, or monitoring checks suddenly fail. That mismatch makes troubleshooting slower than it should be. This post explains what HTTP 999 actually means, why it exists outside the official spec, and which […]

Uptime looks simple until you have to explain it after an incident. A service shows “99.9%,” customers are upset, and someone asks how many minutes were actually down. Without a clear method, the number creates more confusion than clarity. This guide breaks uptime into something you can calculate, defend, and repeat. It covers the basic […]

Website downtime rarely comes from a single, dramatic failure. More often it’s a small change that cascades: a bad deploy, an expired certificate, a resource limit quietly hit, or a dependency that stops responding. The result is the same, users see errors, and teams scramble for answers. This article breaks down the most common causes […]

Open source monitoring tools promise control and flexibility, but the tradeoffs show up fast. Setup takes longer than expected, alerts need tuning, and ownership shifts to your team the moment something breaks at three a.m. Picking the wrong tool can slow response instead of improving it. This article reviews widely used open source monitoring options […]

On November 18th, 2025, a large Cloudflare outage briefly broke big chunks of the internet. For several hours, users around the world were greeted with 500 errors, including platforms like X, ChatGPT, Spotify, and many others that run behind Cloudflare’s network. At UptimeRobot, we sit in a slightly unusual spot during events like this: So […]