15 Accounting APIs to Integrate With in 2026: QuickBooks, Xero, FreshBooks, and Unified Accounting APIs
March 9, 2026
The accounting APIs B2B SaaS teams are most often asked to support in 2026 are QuickBooks, Xero, FreshBooks, NetSuite, Sage Accounting, Sage Intacct, Zoho Books, Wave, Bill.com, Concur, MYOB, Odoo, Microsoft Dynamics 365 Business Central, Stripe and GoCardless. Each has its own authentication model, object structure, pagination rules and webhook support, so this list covers what each API is used for and links to its developer documentation.
If you need several of them, Unified.to's Accounting API reaches 249 accounting integrations, including all 15 below, through one normalized API.
What is an accounting API?
An accounting API lets an application read and write a ledger's records, such as invoices, bills, contacts, journal entries and financial reports, over HTTP instead of through manual exports. For how accounting integrations work, the problems teams run into and when to build versus buy, see What Is an Accounting API?
Why do SaaS teams integrate accounting APIs?
Accounting integrations are valuable because financial data does not live in isolation.
Products often need to connect accounting data with:
- CRM systems
- payment processors
- payroll systems
- procurement workflows
- e-commerce platforms
- BI and analytics tools
Common use cases include:
Automated invoicing
Create invoices from usage, subscriptions, or closed deals.
Expense tracking and categorization
Pull expenses into dashboards or push categorized spend back into the accounting platform.
Real-time financial reporting
Display live invoice, expense, and cash flow data without waiting for nightly syncs.
Reconciliation workflows
Match payments, invoices, and transactions across accounting and payments systems.
Embedded finance or fintech workflows
Use accounting data to power underwriting, insights, forecasting, or spend controls.
Top 15 Accounting APIs to Integrate With in 2026
There are many accounting and financial systems on the market, but these are some of the most important APIs SaaS teams commonly need to support.
1. QuickBooks API
QuickBooks remains one of the most widely requested accounting integrations for SMB and mid-market software.
Typical use cases:
- invoices
- expenses
- contacts
- chart of accounts
- journal entries
- reports
QuickBooks is often essential for:
- invoicing tools
- spend management products
- financial dashboards
- bookkeeping automation
2. Xero API
Xero is a major accounting platform, especially outside the US.
Its API supports:
- invoices
- bills
- contacts
- bank transactions
- accounts
- reports
- tax rates
Xero is commonly used in:
- accounting automation
- cash flow tools
- e-commerce finance workflows
- reporting products
3. FreshBooks API
FreshBooks is popular with service businesses and smaller teams that need lightweight accounting and invoicing workflows.
Common objects include:
- invoices
- clients
- expenses
- estimates
- payments
It is especially relevant for:
- invoicing software
- freelancer tools
- SMB financial products
4. NetSuite API
NetSuite is a much deeper ERP and finance platform used by larger companies.
Teams typically integrate NetSuite for:
- financial consolidation
- order-to-cash flows
- journal entries
- invoices and AR/AP
- enterprise reporting
NetSuite is often a must-have for companies selling into larger accounts.
5. Sage Accounting API
Sage Accounting API documentation
Sage remains important in several regions and segments, especially for SMB accounting and finance use cases.
It commonly supports:
- contacts
- invoices
- ledger accounts
- tax rates
- transactions
6. Sage Intacct API
Sage Intacct API documentation
Sage Intacct is more enterprise-oriented than Sage Accounting and is commonly used in finance-heavy organizations.
Typical integrations include:
- GL data
- AP/AR
- dimensions
- reporting
- multi-entity finance workflows
7. Zoho Books API
Zoho Books is frequently used in smaller and mid-sized businesses, especially when companies already use other Zoho products.
Its API typically includes:
- invoices
- contacts
- bills
- items
- taxes
- expenses
8. Wave API
Wave is relevant for small businesses and freelancer-oriented accounting workflows.
Common use cases:
- invoicing
- bookkeeping
- reporting
- expense visibility
9. Bill.com API
Bill.com developer documentation
Bill.com is especially relevant for AP/AR automation.
It is often used for:
- bill pay
- approvals
- vendor workflows
- invoice management
- payables automation
This makes it important for procurement, AP automation, and spend management products.
10. Concur API
Concur is a major enterprise platform for expense and travel management.
Key use cases:
- expense capture
- reimbursement workflows
- travel + finance reconciliation
- employee spend analytics
11. MYOB API
MYOB matters especially in Australia and New Zealand.
For SaaS teams expanding regionally, it can be an important accounting integration to support.
12. Odoo API
Odoo spans accounting and ERP functionality.
Its accounting integration can matter for:
- invoices
- orders
- contacts
- accounting automation
- custom ERP workflows
13. Microsoft Dynamics 365 Business Central API
Business Central API documentation
Business Central is important for finance and ERP workflows in Microsoft-centric environments.
It is frequently used for:
- finance operations
- invoices
- customers
- vendors
- orders
- reporting
14. Stripe API
Stripe is not a traditional accounting platform, but in practice it is one of the most important financial APIs SaaS teams integrate.
Why it matters:
- payments and invoicing often need to be reconciled with accounting systems
- products frequently combine Stripe with QuickBooks, Xero, or NetSuite
- finance automation workflows often start here
15. GoCardless API
GoCardless is highly relevant for payments and collections workflows, especially recurring payments.
It often shows up in:
- invoice collection workflows
- payment reconciliation
- AR automation
- billing operations
Which other accounting APIs are worth supporting?
Beyond the top 15 above, many SaaS teams also need support for:
This is why accounting integrations increasingly overlap with billing, payments, commerce, and ERP.
What makes accounting APIs hard to integrate?
Accounting APIs are hard to integrate because each platform models financial data, authentication, tax and reports differently.
Different financial data models
Every provider structures:
- invoices
- bills
- transactions
- line items
- tax
- reports
differently.
Even 'simple' objects like contacts can vary based on whether the platform treats them as customers, vendors, suppliers, or all of the above.
Authentication complexity
Some providers use OAuth, some use API keys, and some require more enterprise-specific setup.
Supporting many accounting APIs means handling many auth patterns.
Tax and regional differences
Tax handling is not universal. VAT, GST, US sales tax, exemptions, and provider-specific tax objects all create complexity.
Reports are not standardized
Balance sheet, P&L, trial balance, and cash flow reports are structured differently across systems.
Freshness requirements
For finance, stale data creates real operational problems. A nightly sync might be acceptable for some dashboards, but not for approvals, payment collection, or reconciliation workflows.
How do you integrate with many accounting APIs at once?
A unified accounting API puts one normalized interface, one authorization flow and one schema in front of many ledgers, so you build the integration once instead of once per platform. Unified.to's Accounting API covers 249 accounting integrations, including QuickBooks, Xero, FreshBooks, NetSuite, Sage, Zoho Books, Bill.com and Concur. The objects and operations it supports are listed in the Accounting API overview, with per-integration field support in the capability matrix.
To compare unified API platforms for accounting (Unified.to, Codat, Rutter, Merge, Apideck and Truto), see Best unified API for accounting integrations in 2026.