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BILL Spend and Expense (BYOK) — connector documentation

  • MCP endpoint: https://byok-bill-spend-expense.connectorbay.com/mcp
  • REST API: POST https://byok-bill-spend-expense.connectorbay.com/v1/tools/{tool_name}, described by the OpenAPI 3.1 spec at https://byok-bill-spend-expense.connectorbay.com/openapi.json
  • Transport: Streamable HTTP, stateless, MCP specification 2025-06-18 or later
  • Authentication: your own BILL Spend and Expense Spend & Expense API token, sent in the X-Upstream-Key header of every request (never stored, logged or cached)
  • Health: https://byok-bill-spend-expense.connectorbay.com/health · Tool schemas: https://byok-bill-spend-expense.connectorbay.com/tools.json
  • Publisher: Unify Dynamics LLC · connectorbay.com/byok-bill-spend-expense · agent@connectorbay.com

What BILL Spend and Expense (BYOK) is for

BILL Spend and Expense (BYOK) lets an AI assistant read your own BILL Spend and Expense data through the BILL Spend and Expense API with a key you supply (Spend & Expense API token). Read-only: 7 tools (list_budgets, get_budget, list_transactions, get_transaction, list_reimbursements, get_reimbursement, list_users). The BYOK key travels with each request, is used for that one call only and is never stored, logged or cached; it is only ever sent to gateway.prod.bill.com. Unofficial connector by Unify Dynamics LLC: not affiliated with, endorsed by or sponsored by BILL Spend and Expense. BILL Spend and Expense and its logos are trademarks of their owners and are used only to say which service the connector works with.

Ask your assistant things like:

  • "Which budgets are set up in BILL Spend & Expense?"
  • "Show BILL budget bud_1."
  • "What card spending did we have this week in BILL Spend & Expense?"
  • "Show BILL transaction tx_1."
  • "Which reimbursements are pending in BILL Spend & Expense?"
  • "Show BILL reimbursement re_1."

What it does

  • list_budgets: List spend budgets with name, period, limit, per-transaction cap, receipt rule and retired flag. Cursor-paged.
  • get_budget: Get one budget by id: name, period, limit, per-transaction cap and receipt rule.
  • list_transactions: List card transactions with time, merchant, amount, fees, status, budget, user and receipt status. Pages hold up to 50.
  • get_transaction: Get one card transaction by id with merchant, amount, fees, status, budget, user and receipt status.
  • list_reimbursements: List out-of-pocket reimbursement requests with amount, merchant, note, submitted date, status, type and budget.
  • get_reimbursement: Get one reimbursement by id with amount, merchant, note, dates, status, type, budget and user.
  • list_users: List Spend & Expense users with id, name, role, retired flag and creation time (no contact or birth details).

BYOK key

You bring your own BILL Spend and Expense Spend & Expense API token (https://developer.bill.com/docs/authentication-with-api-token). Your assistant sends it in the X-Upstream-Key header with each request. ConnectorBay uses it for that one call only: it is never stored, logged or cached, never shown in an answer, and it is only sent to gateway.prod.bill.com over https, with no redirects followed. Create a key with the fewest permissions the tools need (read-only if the provider offers it), and revoke it at the provider whenever you like.

Data sources

Live from the BILL Spend and Expense API (gateway.prod.bill.com) with a BYOK key; documentation: https://developer.bill.com/docs/spend-expense-api. Endpoints checked against that documentation on 2026-10-16.

What it is not

Unofficial connector by Unify Dynamics LLC: not affiliated with, endorsed by or sponsored by BILL Spend and Expense. BILL Spend and Expense and its logos are trademarks of their owners and are used only to say which service the connector works with. It is read-only: it never creates, changes, sends or deletes anything in your BILL Spend and Expense account.

Built for: Worldwide. Languages: English.