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Checkly is the industry’s best tool to monitor your production applications. With the power of playwright, developers can test the systems they’ve developed, and roll out those tests as production monitors running from multiple geographies on the Checkly system. And Checkly monitors thousands of API endpoints with complex validation, setup and cleanup scripts, and reliable alerting. So why are we expanding into TCP-based checks? Aren’t those network layer concerns, and outside the responsibilities of application developers?
Networking is shifting Left
10 years ago, it’s true, services that were only available via TCP requests might have been the sole responsibility of network admins. They might use DIY tools to repeatedly ping their services. Of course, at that time network admins might test their network-level resources a few times a month and feel sure that everything was working as expected. In the era of user-created subdomains and container services, our network config changes at the speed of users. As such, we’re shifting left (or is it shifting up?) responsibility for network service availability.
Think about it: how often did your subdomain structure shift, just a few years ago? In fact, you could probably get by with a few hard-coded monitors deployed to some hardware on the network that checked the same five domains, perhaps updating once a year. Now, every time I create a pull request in our documentation repository, Vercel issues me a new subdomain. If we want to monitor a network architecture that’s constantly changing, a dynamic monitoring as code solution is necessary.
Checkly’s TCP Monitoring gives your developers super-powers
Application developers who are already familiar with scripting monitors using Playwright and Checkly, and configuring API checks with Checkly’s API monitors, also need to monitor services that don’t give full HTTP responses, only available for TCP-based requests. Along with basic validation, our new TCP monitors can make SSL requests, finding problems like SSL cite expiry or misconfiguration.
SSL and DNS errors end up being the root cause of application failures. And during those failures, it’s often app teams on-call who’s handling those incidents, we want those app developers to be able to answer on their own ‘it was DNS.’
Key features of Checkly’s TCP Monitoring
Checkly’s TCP monitors offers a new monitoring tool as part of an integrated monitoring solution. TCP monitors are configured in a way very similar to the API checks you know and love, and have the features that separate Checkly from a simple ‘pinger’ service:
- Monitoring as code - no need to manage monitors from a web UI, and you can dynamically integrate the Checkly CLI to do add and manage TCP monitors with scripted tools.
- Setup and cleanup scripts - Need to make a request before you start your check? Need to add a script that will run right after it completes? Checkly’s monitors make sure your synchronous tasks keep your checks up to date and your database clean.
- SSL Verification - don’t let your users be the ones who report expired SSL certificates! Your team can also set up assertions based on certificates, meaning you can send an alert before your cert expires.
- Deep Configuration - is your check one that’s expected to fail? Do you want this check to skip SSL? In the event of a failure, do you want to check after 1, 4, and 16 minutes? Our configuration for each check goes way beyond a simple timeout.
With Checkly, checks on TCP services are a fully fledged part of your monitoring toolkit.
It’s dangerous to go alone: share TCP check results with your team
Of course, since TCP checks are part of Checkly’s monitoring, you’ll expect the full range of alert channels available on any check. Send alerts to SMS, email, Slack, integrated tools like Rootly and PagerDuty, or any webhook you’d like. Further our Checkly dashboards make it easy to get insight into what’s failing and how.
Conclusions: application developers can do more
Developers are now responsible for keeping both apps and networks running smoothly. Checkly’s new TCP monitoring helps with this by letting developers check not just websites and APIs, but also services that only work over TCP, like databases or message queues. With features like SSL checks, setup scripts, and detailed configurations, Checkly makes it easy to catch problems early, whether it’s an expired certificate or a DNS issue. This means fewer surprises and faster fixes.
By adding TCP monitoring, Checkly gives developers everything they need to monitor their entire system in one place. It’s a powerful tool for teams who want to stay ahead of issues and keep their apps running smoothly. With Checkly, you’re not just building great software—you’re making sure it stays reliable, no matter what.
To go further, check out our documentation on TCP checks.