Sage 300 and AvidXchange integration

What moves between them

The main flow is bidirectional. Sage 300 vendor master data and active purchase orders flow into AvidXchange to populate its vendor list and PO records. Approved invoices processed in AvidXchange then flow back into Sage 300's APInvoiceBatches module, mapped to the matching GL accounts and vendors. Reference data such as GL accounts is synced from Sage 300 to AvidXchange so invoice coding lands on valid dimensions.

How ml-connector handles it

ml-connector stores Sage 300's HTTP Basic Auth credentials encrypted and presents them on every request following the uppercase username requirement. For AvidXchange, it uses OAuth 2.0 client credentials to obtain bearer tokens and refreshes them when calls return 401. Because Sage 300 has no webhooks, ml-connector polls vendors and POs on a schedule you define, using OData date filters to fetch only changed records. Invoices approved in AvidXchange are pulled and formatted as APInvoiceBatches payloads, then posted into Sage 300 via its REST endpoint. Vendor and GL account lookups are cached to avoid redundant calls. Every record carries a full audit trail, so failed invoice batches can be reviewed and resubmitted.

A real-world example

A mid-sized manufacturing and distribution company runs Sage 300 on-premises for accounting and supply chain, and uses AvidXchange to centralize invoice receipt and approval across multiple supplier relationships. Before the integration, the AP team received approved invoices from AvidXchange via email or report downloads, then manually re-entered them into Sage 300 with vendor and GL account lookups, a process that consumed two to three hours per invoice batch and introduced coding errors. With Sage 300 and AvidXchange connected, approved invoices flow automatically into Sage 300's AP module every four hours, matched to the correct vendors and cost centers from the Sage 300 master data, eliminating manual re-entry and reconciliation delays at month-end close.

What you can do

• •Sync Sage 300 vendors and purchase orders to AvidXchange to populate the vendor list and matching PO records.
• •Route approved invoices from AvidXchange into Sage 300's AP module with GL account and vendor mappings preserved.
• •Authenticate Sage 300 with HTTP Basic Auth and AvidXchange with OAuth 2.0 client credentials via the WSO2 gateway.
• •Poll Sage 300 for vendor and PO changes on your defined schedule using OData date filters to fetch only changed records.
• •Store credentials encrypted and provide a full audit trail on every vendor, invoice, and batch record.

Questions

What records move between Sage 300 and AvidXchange?

Sage 300 vendors and purchase orders flow into AvidXchange to populate vendor lists and PO records. Approved invoices processed in AvidXchange are pulled and posted into Sage 300's AP module as APInvoiceBatches, matched to vendors and GL accounts from the Sage 300 master data. GL accounts and segments are synced from Sage 300 to AvidXchange so invoice coding lands on valid cost centers.

How does ml-connector handle Sage 300's HTTP Basic Auth and the uppercase username requirement?

ml-connector stores the Sage 300 username and password encrypted and presents them as an Authorization header on every REST call, converting them to uppercase as required by the API. Credentials are never logged or exposed in plaintext, and the audit trail tracks all vendor and invoice activity by user.

Does Sage 300 require a special API user to be created, and how does polling work without webhooks?

Yes, the Sage 300 API user must be created in Administrative Services with the Web API security group assigned; the built-in Admin user does not have API privileges. Because Sage 300 has no webhooks, ml-connector polls vendors and POs on your defined schedule using OData date filters, so only records changed since the last poll are fetched, reducing API call volume and network load.