Introducing our improved uptime check
Published on June 3, 2025 by Freek Van der Herten
The past few months, we’ve working on improving our uptime check. We proud to announce that this improved check is now available for all users. You don’t have to do anything to get it (unless you are not subscribed to Oh Dear, in that case your should subscribe to Oh Dear 😄), all our users now have it enabled by default.
In this blogpost, I’d like to give an overview of the changes and some background why we changed some things.
A bit of history
When Oh Dear was initially built, we only had a handful of checks: uptime, certificate health, and broken links.
Over time we added more checks: DNS, application health, sitemap, and a couple more. One of the checks we introduced after launch was the performance check. It displays a graph that shows the response times of your site. For each minute it has a data point.
Under the hood the performance check is powered by the uptime check. Each time we ping your site to verify it is online, we collect response time data for the performance check. That's why for the performance check to work, you had to have the uptime check enabled.
Because the vast majority of our users have both the uptime and the performance check enabled for their sites, and both of these checks are technically so intertwined, we decided to merge them together.
Let’s take a look at new uptime check
In our UI, you'll only see the uptime check, but the new results page now also includes the performance graph. Here's how that new page looks like.
We also improved what you see when the site is down. The alert is now much more clear, and you can take certain actions right from the alert: request a new run of the check, view your site. You can even post an update directly to the status page that contains your site.
Behind the scenes, we performed an additional technical upgrade. Instead of storing the performance data in our local MySQL database, it now gets saved in a ClickHouse database. This is a database specialized in working with time-based data. This unlocks future improvements we have in mind.
In closing
We do hope that you like our new uptime check. Should you have any remarks, questions or feature requests, let us know!
