Ensure Network Services Stay Online and Responsive With TCP Checks

Monitor databases, message queues, mail servers, and other critical infrastructure with TCP checks. Verify connectivity, detect failures, and prevent outages—all within Checkly’s application reliability platform.

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tcpcheck.ts
import { TcpCheck, TcpAssertionBuilder } from 'checkly/constructs'

new TcpCheck('hello-tcp-1', {
  name: 'Hello TCP',
  activated: true,
  maxResponseTime: 5000,
  degradedResponseTime: 4000,
  request: {
    hostname: 'tcpbin.com',
    port: 4242,
    data: 'ping\n',
    ipFamily: 'IPv6',
    assertions: [
      TcpAssertionBuilder.responseTime().lessThan(1000),
      TcpAssertionBuilder.responseData().contains('ping')
    ]
  }
})

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Monitor Critical Infrastructure Beyond HTTP

Your infrastructure depends on more than just web services. With Checkly’s TCP checks, you can monitor essential backend systems that power your applications.

  • Mail servers (IMAPS, SMTP, etc.) – Ensure email services are online and responsive.
  • Custom TCP services – Validate internal services with data exchange and assertions
  • Firewalls & network rules – Confirm security rules are correctly applied.
screenshot of a tcp check with Checkly

Define & Automate TCP Checks as Code

Integrate TCP monitoring seamlessly into your development workflow. Define checks via the CLI, Terraform, or Pulumi and version-control them alongside your infrastructure.

  1. Code and configure your TCP monitoring

    import { TcpCheck, TcpAssertionBuilder } from 'checkly/constructs'

new TcpCheck('hello-tcp-1', {
  name: 'Hello TCP',
  activated: true,
  maxResponseTime: 5000,
  degradedResponseTime: 4000,
  request: {
    hostname: 'tcpbin.com',
    port: 4242,
    data: 'ping\n',
    ipFamily: 'IPv6',
    assertions: [
      TcpAssertionBuilder.responseTime().lessThan(1000),
      TcpAssertionBuilder.responseData().contains('ping')
    ]
  }
})

  2. Test your TCP checks in your CI/CD

    $ npx checkly test

Running 1 TCP check in eu-west-1.

src/__checks__/hello-tcp.check.ts
   ✔ Hello TCP (120ms)

1 passed, 1 total

  3. Deploy your TCP checks for continuous monitoring

    $ npx checkly deploy --preview

Create: 
    TcpCheck: hello-tcp-1

$ npx checkly deploy

Real-time Insights into Your TCP Monitoring Results

Get a clear, detailed view of your TCP check performance with Checkly’s monitoring dashboard. Track uptime, response times, and failures in real-time to stay ahead of potential issues.

  • Instant visibility – See check results at a glance with pass, fail, and degraded status indicators.
  • Performance metrics – Monitor response times across P50, P95, and P99 percentiles to detect slowdowns early.
  • Historical trends – Analyze past performance and identify recurring issues before they escalate.
  • No blind spots – Get full transparency into connection retries, alerts, and test sessions.

Stay in control of your infrastructure—detect, diagnose, and resolve TCP issues before they impact users.

Simple, Affordable, and Integrated

Full support for Monitoring as Code

Automate and scale monitoring efficiently.

Run checks from private locations

Monitor internal services securely.

Custom failure conditions

Set alerts for timeouts, blocked ports, or incorrect responses.

Single-tool efficiency

Monitor HTTP and non-HTTP services in one platform.

Transparent pricing

Just $2 per 10,000 runs, included in your API check quota.

Works out of the box

No complex setup required—just start monitoring today.

“TCP checks are working nicely for our use case.

We're using them to monitor some of our critical network services. ”

Matt Watkins

Release Engineering Team, The Linux Foundation

Try out Checkly for free

Start monitoring essential backend systems that power your applications.

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