Sage 50 and Airbase integration

What moves between them

The main flow runs from Airbase into Sage 50. Once a bill, payment, expense reimbursement, or card transaction is approved in Airbase, ml-connector writes it into Sage 50 as a purchase invoice or a journal entry, coded to the matching GL account. Vendor records and the Sage 50 chart of accounts flow the other direction so spend in Airbase is coded against accounts and vendors that already exist in the ledger. Reference data is aligned so every posted line lands on a valid Sage 50 account. The cadence is driven by an Airbase webhook or a poll where webhooks are not enabled, plus a scheduled poll of Sage 50 through the local agent.

How ml-connector handles it

ml-connector deploys a lightweight Windows agent on the Sage 50 machine because the SDK needs an interactive desktop session and cannot run as a headless service. The agent uses a dedicated Sage 50 user account, since only one SDK session can hold the company file open at a time, so the integration login is kept separate from the person using Sage 50 at their desk. Both credential sets are stored encrypted: the Sage 50 username and password on the agent side, and the Airbase Bearer token plus tenant base URL on the cloud side. Approved Airbase spend is filtered by status before it is written, so a bill that is still pending approval is never posted. GL accounts and vendors are mapped first, so every purchase invoice and journal line references a Sage 50 account that exists. Where Airbase webhooks are enabled, an approval event triggers a sync; otherwise the connector polls. Sage 50 is always polled, because the desktop product never pushes. Because the SDK accepts no idempotency key, ml-connector checks for an existing record by reference number before creating one, and stores the Sage-assigned internal ID in a mapping table so a retry does not double-post. The agent matches the installed Sage 50 version, and reconnects after the machine reboots. Every record carries a full audit trail and can be replayed if a write fails.

A real-world example

A 90-person construction services firm runs Sage 50 in its back office for the general ledger and vendor payments, and rolled out Airbase so field managers could request purchases and submit card and expense spend from their phones. Before the integration, a bookkeeper printed approved bills and expense reports from Airbase each week and re-keyed every one into Sage 50, picking the GL account by hand and reconciling card statements line by line at month-end. With Sage 50 and Airbase connected, each approved bill, payment, and card transaction posts into Sage 50 automatically against the right account, and the vendor list and chart of accounts stay aligned. The weekly re-keying is gone and the card reconciliation is already done when close begins.

What you can do

• •Post approved Airbase bills, payments, expense reimbursements, and card transactions into Sage 50 as purchase invoices and journal entries.
• •Send Sage 50 vendors and the chart of accounts to Airbase so spend is coded against real accounts.
• •Map Airbase GL coding to Sage 50 accounts so every posted line lands on a valid account.
• •Bridge the Sage 50 local username and password login to the Airbase tenant Bearer token through one encrypted agent.
• •Run on a schedule through the local Windows agent, with retries, reference-number deduplication, and a full audit trail.

Questions

How does ml-connector reach Sage 50 if it has no cloud API?

Sage 50 is desktop software with no REST API, so ml-connector runs a small Windows agent on the same machine as Sage 50 and uses the local SDK. The agent authenticates with a dedicated Sage 50 username and password and syncs data to Airbase over HTTPS. The machine needs to stay on and logged in for syncs to run.

Which direction does data move between Sage 50 and Airbase?

Approved spend moves from Airbase into Sage 50, where bills, payments, expense reimbursements, and card transactions are written as purchase invoices and journal entries. Vendor records and the chart of accounts move from Sage 50 up to Airbase so spend is coded against real accounts. Reference data is aligned in both directions so every posted line lands on a valid Sage 50 account.

What keeps the integration from posting unapproved spend or duplicate records?

Airbase bills, expenses, and POs run through approval chains, so ml-connector filters by status and only writes records once they are approved. Because the Sage 50 SDK accepts no idempotency key, the connector checks for an existing record by reference number before creating one and stores the Sage-assigned ID in a mapping table. A retry therefore updates the existing record instead of double-posting.