Turn the Coupa Supplier Portal into an API

What you can build on the CSP

• Get purchase orders

  Build this

  Reads the Purchase Orders table on the Orders page for the customer you pick in Select Customer.

  Takes

  Customer, status (optional)

  Returns

  PO number, order date, status, acknowledged at, items, unanswered comments, total

• Check invoice statuses

  Build this

  Reads the Invoices table for one customer, with each invoice's status and, for a disputed invoice, the dispute reason.

  Takes

  Customer, status (optional)

  Returns

  Invoice number, created date, status, PO number, total, unanswered comments, dispute reason

• Get invoice payments

  Build this

  Reads Invoice Payments on the Payments page for one customer: which invoices were paid, how and when.

  Takes

  Customer, released since (optional)

  Returns

  Payment number, invoice number, status, payment method, payment released date, total

• Create an invoice from a purchase order

  Build this

  Opens a PO on the Orders page, selects Create Invoice, fills in the invoice, attaches the PDF and submits it or saves it as a draft.

  Takes

  Customer, PO number, invoice number, invoice date, invoice PDF, submit or draft

  Returns

  Invoice number, status, PO number, total

Automate the CSP with a workflow

A workflow runs your methods as one process, with nobody at the screen. A schedule or a call from your own system starts it, the steps run in order, and the result arrives in your inbox or in the systems you already use.

• Unacknowledged purchase orders, every customer

  Build this

  Starts

  Every weekday at 7:00

  Step 1

  For each customer you name, get the purchase orders in Issued status.

  Step 2

  Keep the POs with nothing in Acknowledged At.

  Step 3

  Email you the list, one section per customer.

• Newly disputed invoices, with the dispute reason

  Build this

  Starts

  Every weekday at 9:00

  Step 1

  For each customer, check the Invoices table for the Disputed status.

  Step 2

  Keep the invoices that were not disputed on the last run.

  Step 3

  Post each one, with its PO number, total and dispute reason, to your Slack or ERP webhook.

• Released payments, posted to your accounting system

  Build this

  Starts

  Every day at 18:00

  Step 1

  For each customer, get the Invoice Payments released since yesterday.

  Step 2

  Stop when there are none.

  Step 3

  Post payment number, invoice number, payment method, released date and total to your webhook.

You can run a workflow by hand on every plan, Free included. Schedules and webhook triggers come with the paid plans, from $29 a month.

Once built, one call from your code

Once you have built a method, it is one POST to /v1/runs from your backend, or a tool an AI agent calls over MCP. This is what “Get purchase orders” would look like.

curl https://api.fous.com/v1/runs \
  -H "Authorization: Bearer $FOUS_API_KEY" \
  -H "Content-Type: application/json" \
  -d '{
    "method": "supplier.coupahost.com/get_purchase_orders",
    "input": {
      "customer": "Acme",
      "status": "Issued"
    }
  }'

{
  "status": "completed",
  "data": {
    "customer": "Acme",
    "orders": [
      {
        "po_number": "10482",
        "order_date": "2026-11-09",
        "status": "Issued",
        "acknowledged_at": null,
        "items": "40 Each of Hydraulic hose, 3/4 in",
        "unanswered_comments": false,
        "total": 3180,
        "currency": "USD"
      }
    ],
    "count": 1
  }
}

An example with invented data, not a ready-made endpoint. The method exists in your organization once you build it, and its name, inputs and fields follow your request.

The CSP’s own options

Coupa documents a CSP REST API that reads your invoices and purchase orders. It is for suppliers on Coupa Advanced, a paid subscription Coupa lists at $4,800 USD a year, and using it consumes tokens. The portal itself is free, and cXML is arranged with each customer.

Read on November 11, 2026: Coupa Supplier Portal REST API, Tokens in the Coupa Supplier Portal, Coupa supplier offerings and pricing.

Signing in to the CSP

The CSP asks for your email address and password, then a multifactor step when it is on: an authenticator app, SMS, email or a passkey. One account reaches every customer you are connected to. With Fous you sign in once through the CSP's own sign-in with your own account: the login is sealed with AES-256, two-step sign-in by emailed code is handled, and an expired session is signed back in.

Worth knowing

One customer at a time

The Orders, Invoices and Payments tables show one customer, chosen in the Select Customer list. The All view across customers is part of Coupa Advanced, so a method takes the customer as an input.

Your customer's settings decide what is allowed

Buttons are active only for actions your customer has enabled. Depending on those settings you may have to accept a PO before invoicing it, and a PO in Soft Closed status cannot be invoiced.

A submitted invoice cannot be edited

To change an invoice after submitting it, you have to contact your customer. You need a legal entity before you can create an invoice, and only draft invoices can be deleted.

Three active sessions, 30 days per browser

A CSP user cannot have more than three active sessions at once. Remember this browser skips the multifactor step for 30 days, and changes to legal entities, remit-to or bank details always ask for it.

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