--- updatedAt: 2026-08-17T18:03:37.000Z --- Fetch the complete documentation index at: https://developer.bill.com/llms.txt. Use this file to discover all available pages before exploring further. Append .md to any documentation page URL to get its markdown version. # BILL v3 API The BILL v3 API follows the REST architecture. We use all the standard REST verbs (`GET`, `POST`, `PUT`, `PATCH`, and `DELETE`) and provide HTTP response codes. BILL offers a comprehensive sandbox environment where you can test workflows, from creating bills to completing AP payments, without moving real money. See Sandbox vs Production to learn about the two BILL development environments. | Workflow | API | What can you do? | | :----------- | :------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------ | :-------------------------------------------------------------------------------------------------------------------------------------------------------------------- | | AP | Vendors
Bills
Bill approvals
Payments
Vendor credits | Create bills & pay vendors at scale with a wide range of payment methods. Create bulk bills & bulk payments. Generate payment disbursement reports. | | AR | Customers
Invoices
Charge customers
[Credit memos](https://developer.bill.com/docs/ar-credit-memos)
Record payments | Generate invoices & send invoices to get paid by customers. Charge authorized customers for invoices. Record offline payments received outside the BILL platform. | | BILL Network | BILL Network | Connect with over 7 millions of customers and vendors in the BILL Network. BILL automatically enables payments to connected vendors with ACH, virtual card, or check. | | S\&E | Budgets
Cards
Transactions
Reimbursements | Build with card & expense management services. Set up budgets, users, & virtual cards. Manage transactions & reimbursements. | | Webhooks | Webhooks | Subscribe to & receive real-time notifications for AP & AR events and S\&E events. | # Sign-up Sign-up and generate a developer key to begin testing with the BILL AP & AR API. With this key, you can build with the AP, AR, BILL Network, and webhook workflows. See Sandbox API sign up for more information. ## Spend & Expense API A BILL S\&E API token is required for you to begin testing with the Spend & Expense API. You can build with budgets, users, and virtual cards. In addition, you can manage transactions and reimbursements. See Authentication with Spend & Expense API token for more information. ## Partner operations As a BILL partner, you can perform partner-level operations, which include creating an organization, and then creating and managing users for that organization. See BILL partner operations for more information. # Documentation resources Learn more about the BILL v3 API services with a range of documentation resources. | Section | Description | | :---------------------------------------------------------------------------------------------------------------------------------------- | :--------------------------------------------------------------------------------------------- | | API guides | Introduction to the core BILL v3 API concepts. | | API reference | Complete list of BILL v3 API endpoints with request & response fields explained. | | Postman Collection | Simply fork the BILL Postman Collection & begin testing with different BILL v3 API workflows. | | Video tutorials | Developer tutorial videos to learn how to build with different BILL v3 API workflows. | | Common API error codes | Common BILL error messages for API operation failures. | | FAQs | Frequently Asked Questions (FAQs) about the BILL v3 API workflows. | | BILL Help Center | BILL knowledge base with help & support resources for BILL customers. | | BILL Developer Terms | Legal agreement between BILL and any organization you identify in your registration with BILL. |