There is no dedicated Acumatica node in n8n, which throws people off, but it is not a problem. Acumatica exposes a full contract-based REST API, and n8n's generic HTTP Request node speaks to it perfectly. The integration is really three things: authenticate, call the right endpoint, and handle Acumatica's pagination and events sensibly.
Authenticate once, reuse the session
Acumatica's REST API is session-based: you log in against /entity/auth/login with credentials, receive a session cookie, and send that cookie on subsequent requests until you log out. The cleanest pattern in n8n is a login step at the start of the workflow that captures the cookie, then reuse it across the calls that follow. Acumatica limits concurrent logins per licence, so log out when you are done rather than leaking sessions.
POST https://erp.example.com/entity/auth/login
Content-Type: application/json
{ "name": "integration_user", "password": "***", "company": "MyCompany" }
# Response sets a session cookie — carry it on every following request.Drive endpoints with HTTP Request
Once authenticated, every operation is an HTTP call against a contract endpoint like /entity/Default/24.200.001/SalesOrder. GET to read (with $filter, $select, and $expand to shape the response), PUT to create or update. Keep the endpoint version pinned in the URL so an Acumatica upgrade does not silently change your payloads. Use $select aggressively — pulling only the fields you need makes the calls faster and the responses easier to map.
Pagination and events
Large result sets come back paged. Use $top and $skip to page through, and loop in n8n until a page returns fewer rows than the page size. To react to changes in Acumatica rather than poll, configure an Acumatica business event with a webhook target pointing at an n8n Webhook node — that turns "check every five minutes" into "run the moment it happens."
Acumatica meters API usage and limits concurrent sessions by licence tier. A chatty n8n workflow that logs in per item or never logs out will exhaust the session pool and start failing. Authenticate once per run, reuse the cookie, page efficiently, and log out at the end — treat sessions as the scarce resource they are.
n8n plus the contract REST API is a complete Acumatica integration toolkit: one login, HTTP Request nodes against versioned endpoints with tight $select/$filter, loop-based pagination, and business-event webhooks for real-time triggers. No custom node required — just disciplined use of the API you already have.
Independent software engineer in Nairobi specialising in Acumatica customisations, Laravel backends, and tax fiscalisation integrations across East and Southern Africa.