cloudparts

Checkly

Hosted synthetic monitoring written as code: API checks, uptime monitors and Playwright browser tests defined in TypeScript next to your app, tested with a CLI and deployed to run from 22 locations.

What it is
Synthetic monitoring
Used for
Alerting
Type
Commercial product
Made by
Checkly Inc.
License
Proprietary (the Checkly CLI is Apache 2.0)
Facts checked
23 October 2026
Website Source code

What it is

Checkly runs checks against your product on a schedule from cloud locations: 22 public ones across the Americas, Europe and Asia Pacific (most on AWS), or a private location where you run Checkly’s agent inside your own network. Uptime monitors cover URLs, TCP ports and DNS. API checks send a request and assert on the status, headers and JSON body. Browser checks are Playwright scripts, and multistep checks script a flow of several API requests. Playwright Check Suites take an existing Playwright test project as it is, selecting tests by project or tag from playwright.config, and run it as a monitor for up to 30 minutes per run. Each failed run keeps the trace, video, screenshots and logs, and alerts go to email, SMS, phone, Slack, Teams or webhooks; Checkly also hosts status pages and dashboards.

The defining idea is “monitoring as code”. Checks, alert channels and groups are TypeScript constructs such as ApiCheck or BrowserCheck, kept in the application’s repository with a checkly.config.ts that sets defaults like frequency and locations. npx checkly test dry-runs them on Checkly’s infrastructure, and npx checkly deploy creates, updates or deletes the matching resources, like a small Terraform for monitors (a Terraform provider exists too). Pricing is per run: a free Hobby plan includes 10,000 API check runs and 1,000 browser runs a month, and a 45-second Playwright suite counts as two browser runs.

Why teams pick it

  • Checks live in the same repository and pull requests as the code they test, and the same CLI can run them before they go live
  • Reuses Playwright: end-to-end tests become production monitors without rewriting, with traces and videos for every failure
  • Runs from 22 regions, or from private locations inside your network
  • Monitoring, alerting and status pages in one service with a usable free tier

Watch out for

  • Hosted only: private locations can run checks inside your network, but scheduling, results, alerting and the UI live in Checkly’s cloud
  • Billed per run, and retries and extra locations each count as another run, so frequent browser checks from many regions add up
  • Free-plan quotas are hard caps: checks stop when the month’s runs are used up
  • Monitoring as code assumes JavaScript or TypeScript: constructs and browser checks are written in it

Alternatives

What all synthetic monitoring have in common →Compare side by side →
Uptime KumaOpen sourceA self-hosted uptime monitor in one Node.js container: HTTP, TCP, ping, DNS, database and browser checks as often as every 20 seconds, 90+ notification services and public status pages, all set up in a web UI.

How it fits with other technologies

An API check as code, then test and deploy it · ts

// __checks__/api.check.ts
import { ApiCheck, AssertionBuilder } from 'checkly/constructs'

new ApiCheck('api-health-check', {
  name: 'API Health Check',
  request: {
    url: 'https://danube-web.shop/api/books',
    method: 'GET',
    assertions: [
      AssertionBuilder.statusCode().equals(200),
    ],
  },
})

// $ npx checkly test     # run once from Checkly's locations
// $ npx checkly deploy   # create or update the monitor

See it in a real stack

No architecture uses Checkly yet. Drop it into the playground and wire it up yourself.Open playground →
Where it came from2018–2024

Tim Nolet created Checkly in Berlin as a side project to give developers signals about their apps’ performance and downtime. By 2018 its site sold “active monitoring” of two things: API endpoints, checked from up to 8 locations as often as once a minute, and site click flows such as logins and shopping carts, scripted with Google’s Puppeteer and run in Chrome. Checkly also published Headless Recorder, a Chrome extension that turned clicks into Puppeteer or Playwright scripts; it was deprecated in December 2022.

TechCrunch names Hannes Lenke (now CEO), Nolet and Timo Euteneuer as co-founders. In April 2020 Accel led a $2.25 million seed round. Browser checks later moved from Puppeteer to Playwright, and in February 2023 Checkly introduced its CLI and “monitoring as code” workflow, so checks could be written, reviewed and deployed with the application.

In July 2024 Balderton Capital led a $20 million Series B, bringing total funding to $32.25 million; the company then had a 35-person team, more than 1,000 paying customers and ran 32.5 million checks a day. It launched Checkly Traces at the same time, and later Playwright Check Suites, which run whole existing test projects as monitors.

Why it’s built this way

Monitors as TypeScript in the repository
Clicking checks together in a UI drifts away from the code they test. Constructs deployed by a CLI let developers review, test and version monitors like application code.
Real browser scripts, not recorded macros
Checkly built browser checks on Puppeteer and then Playwright, the libraries developers already use for end-to-end tests, so the same tests can serve both purposes.
Price by check run
Billing per run, not per host or seat, ties cost to how often and from how many places you check.

Timeline

  1. 2018

    Checkly sells API checks and Puppeteer browser checks from up to 8 locations

  2. 2018

    Headless Recorder Chrome extension released

  3. 2020

    $2.25 million seed round led by Accel (April)

  4. 2023

    Checkly CLI and monitoring as code introduced in beta (February)

  5. 2024

    $20 million Series B led by Balderton; Checkly Traces launched

Sources12 · facts checked 23 October 2026

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