API documentation

Introduction

Dominder is an API-only domain monitoring service. You describe the domains you care about over a REST API; we watch them for reachability, SSL health, and DNS drift; and we POST a signed webhook to your system the moment something breaks.

You're reading this athttps://dominder.co/docs. The API base URL in every example below ishttps://dominder.co/api/v1- replace it if you're self-hosting somewhere else.

How it works

  1. You subscribe and grab your API key from your account page.
  2. You set a webhook URL - the public HTTPS endpoint on your service that should receive notifications.
  3. You POST the domains you want to watch to the Dominder API, along with the checks you want run against each.
  4. Our scheduler runs those checks on a heartbeat. Results are stored and the most recent status is cached on each domain.
  5. Any time a domain transitions between healthy and failing, Dominder POSTs a signed JSON payload to your webhook URL.

Conventions

  • Base URL. All API requests go tohttps://dominder.co/api/v1.
  • HTTPS required. API calls over plain HTTP are rejected in production.
  • JSON in, JSON out. SendContent-Type: application/json. Responses are always JSON, UTF-8 encoded.
  • Authentication. Every request must include your API key in a header. SeeAuthentication.
  • Identifiers. Resource IDs are 24-character hex strings (MongoDB ObjectIds).
  • Timestamps. ISO 8601, UTC, e.g.2026-04-22T12:34:56.789Z.

What we check

Reachability

HTTP GET to the domain. We try HTTPS first and fall back to HTTP. Anything returning less than 400 is healthy.

SSL certificates

Strict TLS handshake. Fails on expired, self-signed, or mismatched certs. Warns when under 14 days to expiry.

DNS records

Pin A, AAAA, CNAME, MX, TXT, or NS records to expected values and get alerted on drift.

See theMonitoring checkspage for the full rules each check applies.

Next steps

Quickstart 

From zero to your first webhook in under ten minutes.

Domains API 

Full reference for creating, updating, and removing domains.

Webhooks 

Payload format, HMAC signature verification, retry behavior.

Errors 

The error envelope and what each HTTP status code means.