Checks are tests and assertions created and run after every successful deployment. Checks API defines your application's quality metrics, runs end-to-end tests, investigates APIs' reliability, and checks your deployment.

Most testing and CI/CD flows occur in synthetic environments. This leads to false results, overlooked performance degradation, and missed broken connections.

The diagram shows the complete lifecycle of how a check works:

1. When a deployment is created, Vercel triggers the deployment.created webhook. This tells integrators that checks can now be registered
2. Next, an integrator uses the Checks API to create checks defined in the integration configuration
3. When the deployment is built, Vercel triggers the deployment.ready webhook. This notifies integrators to begin checks on the deployment
4. Vercel waits until all the created checks receive an update
5. Once all checks receive a conclusion, aliases will apply, and the deployment will go live

Learn more about this process in the Anatomy of Checks API

You can create a native or connectable account integration that works with the checks API to facilitate testing of deployments for Vercel users. The Checks API reference lists the endpoints your integration calls to create and update checks.

Vercel users can find and install your integration from the Marketplace under testing, monitoring or observability.

Once you have created your integration, publish it to the marketplace by following these guidelines:

• Provide low or no configuration solutions for developers to run checks
• A guided onboarding process for developers from the installation to the end result
• Provide relevant information about the outcome of the test on the Vercel dashboard
• Document how to go beyond the default behavior to build custom tests for advanced users