API Documentation

OnChange REST API

Programmatic access to your monitors, changes, and notifications. Build dashboards, automate workflows, and integrate OnChange into your toolchain.

Authentication

Pass an API key in theX-API-Keyheader. Issue per-integration keys with their own scopes and expiry fromSettings → API.

Base URL

Every endpoint lives underhttps://onchange.app/api/v1and returns JSON. Default rate limit is 120 requests per minute per key — admins can raise that for partner keys.

Pagination

List endpoints support page-based pagination usingpageandper_pagequery parameters. Default is 20; monitor lists allow up to 500.

Authentication

Issue a key

Open Settings → API.
Click New key, name it after the integration that will use it, and pick the scopes it needs.
Copy the secret. It is shown exactly once.

Use the key

Send the secret in the X-API-Key header on every request. Keys carry scopes — calls without the right scope return 403.

If a key is compromised, revoke it from the same settings page. Revocation is immediate.

Scopes

Scopes follow resource:action where action is read or write. Pick the smallest set your integration needs.

Scope	Grants
monitors:read	List, fetch, and inspect monitors.
monitors:write	Create, update, pause, delete monitors.
changes:read	Read change history, diffs, and AI summaries.
changes:write	Mark changes as useful / noise; archive.
alerts:read	List alert destinations and rules.
alerts:write	Create or modify alert destinations and rules.
reports:read	Download generated reports.
webhooks:read	Inspect outbound webhook deliveries.
users:read	Read your own profile and API keys.
users:write	Manage your own API keys.

Rate limits

Default ceiling is 120 requests / minute per key. Each issued key gets its own bucket — multi-key customers are not penalized for having many integrations.

Admins can raise the ceiling for individual keys (partner integrations, internal automations). Need a higher limit? Get in touch.

Exceeding the limit returns 429 Too many requests. Back off and retry after the bucket refills.

OpenAPI specification

Full machine-readable spec for the public surface. Drop it into Postman, Insomnia, or any OpenAPI-aware client to generate a request collection.

Download openapi.json

Example request

curl https://onchange.app/api/v1/monitors \
  -H "X-API-Key: ock_..." \
  -H "Content-Type: application/json"

Interactive API Explorer

Try any endpoint live. Enter your API key and send requests directly from this page.

Authentication

Add your API key to try endpoints live. Find it in Settings → API Key.

Monitors

Changes

Timeline & Values

Crawl

Alert Rules

Accessibility

Reports

Status Pages

Export

User

Monitors

Changes

Timeline & Values

Crawl

Alert Rules

Accessibility

Reports

Status Pages

Export

User

Error codes

Code	Meaning
200	Success
201	Created
400	Bad request - invalid parameters
401	Unauthorized - invalid or missing API key
403	Forbidden — API key is missing the required scope (response includes required_scope)
404	Not found
429	Rate limited - too many requests
500	Internal server error

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