Documentation Index
Fetch the complete documentation index at: https://docs.arcuserp.com/llms.txt
Use this file to discover all available pages before exploring further.
1. Get an API key
Sign in to app.arcuserp.com, open Settings, then click Developers. On the API Keys tab, click Create API key.- Name: give it a descriptive label (e.g.
My Integration) - Mode: choose Test for sandbox or Live for production
- Scopes: select at minimum
accounts:readto follow this guide
API keys are entity-scoped. The entity ID is part of the URL path:
/v1/entities/{entity_id}/{resource}. Every request is automatically scoped to the entity that issued the key.Where to find your entity ID
Your entity ID is a UUID that identifies your organization in Arcus. You need it for every API request. Easiest way: Go to Settings > Developers > API Keys. The Quick Reference panel at the top of the page shows your Entity ID with a copy button right next to it. Once you have both values, set them as environment variables:2. Make your first request
List the first five accounts in your entity:3. Understand the response
Every list endpoint returns the same envelope:starting_after with the last ID in data:
4. Create your first order
Next steps
Authentication
Entity-scoped keys, scopes, and IP allowlists.
Concepts
Idempotency, pagination, expand, errors, and more.
API Reference
Every endpoint documented with try-it-now.
Webhooks
Subscribe to real-time order, payment, and fulfillment events.

