Finance & ERP · Integration
Brex
Add Brex to your product for your customers, and give your AI agents governed access to it.
Embed a Brex integration so your customers can manage their own cards, transactions, expenses, and budgets from inside your product, with governed agent access to the same records. Writes are idempotent, so a retry after a timeout does not create a duplicate record, and every call is logged per tenant so a spend decision can be traced to the event that caused it. fastn handles each customer's OAuth and API upkeep, so onboarding another Brex account is configuration rather than a release.
In your product
Embedded for your customers. Per-tenant auth, no per-customer code, maintained by fastn.
Let customers connect their own Brex account and read card transactions into your product for coding and reporting.
Issue and update virtual cards with spend limits from your product so controls are set where the work happens.
Read and update expenses, receipts, and their memos so expense review happens without a tab switch.
Trigger your product when a transaction posts or a budget threshold is crossed.
For your AI agents
Governed, audited access for the agents you build, through the MCP server.
An agent reads recent transactions and flags the ones missing a receipt or category.
An agent issues a limited virtual card for an approved purchase within governed permissions.
An agent reacts to a budget threshold event and notifies the budget owner.
Example prompt
List transactions over 500 from last month with no receipt attached and show the cardholder for each.
Set up Brex in 4 steps
- 01Open the Brex connector from your fastn dashboard.
- 02Have each customer authenticate their own Brex account with OAuth and least-privilege scopes.
- 03Map the transaction, expense, and budget fields your product uses, then enable actions and triggers.
- 04Call them from your product, or expose them to an agent through the MCP server.
Why teams use the Brex integration
What you get by embedding it with fastn instead of building it yourself.
- Ship a Brex integration without building it. Your customers connect their own Brex account inside your product and work their invoices, payments and vendors there, with no per-customer code on your side.
- Handle the part that actually costs time: financial writes must be idempotent and reconcilable, because a duplicate is an accounting problem rather than a bug. fastn owns the auth, token refresh, rate limits, pagination and breaking-change fixes, so a Brex update is not your on-call problem.
- One integration serves your product and your agents. The same governed Brex connection powers in-product features and gives AI agents scoped, audited access, so you move financial records without hand-keying them between systems without wiring it twice.
Used by these teams
Compare with
NetSuite
BlackLineWorks well with
StripeOften used alongside
Tools the same teams tend to run next to Brex, across other categories.
Shopify
BigCommerce
AfterShip
ChargebeeBrex integration FAQ
How do I add a Brex integration to my product?
Enable the Brex connector in your fastn dashboard, then let each customer authenticate their own Brex account. fastn handles the OAuth flow, token storage and refresh per tenant, so there is no Brex client code in your app and no per-customer branch in your codebase. Setup is 4 steps.
Do my customers each connect their own Brex account?
Yes. Every connection is scoped to the individual customer, so each authorises their own Brex account and only ever sees their own invoices, payments and vendors. That per-tenant isolation is the point of an embedded integration: you support the long tail of customer setups without maintaining an integration per customer.
Can AI agents use this Brex integration?
Yes. The same connection is exposed to your agents through the fastn MCP gateway, with permissions scoped per tenant and every call audited. An agent reads recent transactions and flags the ones missing a receipt or category.
Who maintains the Brex integration?
fastn does. When Brex changes an endpoint, deprecates a field or alters its auth, the fix lands in the connector rather than in your backlog, and your customers' connections keep working.
Is the Brex integration safe for financial writes?
Writes are idempotent, so a retry after a timeout does not post a document twice, and every call is logged per tenant so an entry can be traced back to the event that created it. That matters more in finance than anywhere else, because a duplicate is a number somebody has to explain.
Can it handle each customer's own chart of accounts?
Yes. ERP deployments are configured to the business, so account structures, required fields and fiscal calendars differ per customer. Those are mapped per tenant as configuration, not hard-coded.
What about Brex rate limits during a first import?
Backfills are throttled deliberately. ERP limits are often account-wide rather than per-integration, so an unthrottled import can exhaust a customer's allowance and disrupt their other integrations.
What can I build with the Brex integration?
A common starting point: connect their own Brex account and read card transactions into your product for coding and reporting. Teams also use it for the other use cases listed above, and expose it to agents for governed reads and writes.
How much does the Brex integration cost?
It is included. Pricing is based on connected accounts, not on how many connectors you enable, so adding Brex does not change your per-connector cost. You can start free with 3 connected accounts.
Add Brex to your product
Start free with 3 connected accounts. No sales call required, and no per-customer integration code.