Key facts
- Both use OAuth 2.0 with short-lived access tokens and refresh tokens
- Xero's API pricing tiers, effective from 2 March 2026, are based on connections and data egress, according to Apideck
- Intuit's App Partner Program keeps write (Core) calls free and meters read (CorePlus) calls, according to Apideck
- Xero applies per-organisation limits per minute and per day; QuickBooks applies per-company limits
- Both support webhooks for changes to invoices, contacts and payments
- dijitul has built accounting integrations since its KashFlow work around 2011
The short answer
If you are choosing accounting software, choose on accounting fit, your accountant's preference and the apps you need. Both Xero and QuickBooks Online have APIs good enough for nearly any custom integration. If you already use one, there is rarely an integration reason to switch.
If you are building software that will connect to many customers' accounting systems, the details below matter more, especially the new developer pricing on both platforms, and you will probably need to support both.
Comparison table
| Factor | Xero API | QuickBooks Online API |
|---|---|---|
| Authentication | OAuth 2.0; access tokens last 30 minutes, with refresh tokens | OAuth 2.0; access tokens last one hour, with refresh tokens |
| Rate limits | Per organisation: calls per minute, per day and concurrent requests | Per company: requests per minute, plus batch and concurrency limits |
| Developer pricing | Tiers by number of connected organisations and data egress | Partner tiers; write calls free, read calls metered above an allowance |
| Webhooks | Contacts, invoices and other events, signed with a key | Entity change notifications, signed with a verifier token |
| Bulk operations | Many endpoints accept arrays of records | Batch endpoint for multiple operations |
| Querying | Filters, modified-since headers, paging | SQL-like query language, change data capture endpoint |
| Sandbox | Demo Company per developer account | Sandbox companies per developer account |
| UK tax | UK VAT and Making Tax Digital supported | UK VAT and Making Tax Digital supported |
| Best for | Read-heavy integrations need care with egress | Read-heavy integrations need care with CorePlus usage |
API pricing: the change that matters in 2026
Both platforms changed how they charge developers, and it affects integration design.
Xero introduced tiered developer pricing effective from 2 March 2026, based on how many Xero organisations connect to your app and how much data you download. Pushing data into Xero (ingress) is not charged; data you read (egress) counts towards your tier's allowance, according to Apideck's summary of Xero's terms. A private integration connecting your own single organisation sits in the lowest tier.
Intuit runs the App Partner Program for QuickBooks Online. Core calls, which are mostly writes such as creating invoices and customers, are free. CorePlus calls, mostly reads and reports, are metered, with a free allowance on the entry tier and a hard cap that blocks further calls until the next month, according to Apideck.
The design lesson is the same for both: write freely, read carefully. Use webhooks and change-tracking rather than polling, cache reference data such as accounts and tax rates, and fetch only what changed. We build integrations that way by default.
Data model differences that catch people out
- Tax: Xero uses tax types on each line; QuickBooks uses tax codes and rates with different structures in UK and US companies. Mapping VAT correctly is the most common source of errors.
- Items and inventory: both support tracked items, with different rules for cost and quantity adjustments.
- Payments and clearing: payment provider payouts (Stripe, PayPal, Shopify Payments) need clearing accounts and fees posted separately in both.
- Tracking: Xero has tracking categories; QuickBooks uses classes and locations.
- Idempotency: neither platform will stop you creating the same invoice twice, so your integration must check before it writes.
Typical integrations we build with either platform
The same handful of integration patterns covers most requests, whichever accounting platform you use:
- Ecommerce to accounts. Orders, refunds and payment provider payouts from Shopify, WooCommerce or a bespoke shop, posted as invoices or daily summaries with the right VAT and clearing accounts.
- Billing systems. Usage or subscription billing generating invoices in the accounting platform, with payment status flowing back. This is close to the automated billing software we first built for energy usage.
- Customer portals. Customers see invoices, statements and balances pulled from the accounting system, and pay by card or Direct Debit.
- Purchase and expense capture. Supplier invoices read with AI, matched to purchase orders, and posted as bills for approval.
- Reporting. Financial data combined with operational data in a dashboard, using incremental reads to keep API usage low.
In each case the design work is mostly the same: decide which system owns which data, map tax and accounts carefully, and make every write safe to retry.
How we build accounting integrations
dijitul developments has built accounting integrations since we connected OpenCart shops to KashFlow around 2011, creating customers, invoices on payment, stock updates and credit notes automatically. Today our Xero integrations and QuickBooks integrations use the same principles: queued jobs, token refresh handled centrally, rate-limit aware retries, idempotency checks before writes, and an audit log your finance team can read.
If you are building a product for many customers, we usually put an adapter layer in front of both APIs so the rest of your code does not care which one a customer uses. See accounting software integration and Zapier vs custom integration.
Frequently asked questions
Should we switch accounting software for a better API?
Rarely. Both Xero and QuickBooks Online have capable, well documented APIs. Choose on accounting fit, the apps you need and your accountant's advice. dijitul can integrate custom software with whichever you use, so the API should not drive the decision.
Do the new API pricing rules affect our own integration?
Possibly, though a private integration with your own single organisation usually sits in the free or lowest tier. Read-heavy designs cost more under both platforms' models, so dijitul designs integrations to rely on webhooks and incremental reads.
Can you integrate with both Xero and QuickBooks in one product?
Yes. For software sold to many businesses, dijitul builds an adapter layer so your application talks to one internal interface, and each accounting platform's authentication, data model and limits are handled behind it.
How do you prevent duplicate invoices?
We store the external reference of every record we create and check it before writing, use each platform's references or document numbers, and queue retries so a timeout cannot create a second invoice.
What about Sage and KashFlow?
We integrate with those too. Sage Business Cloud Accounting has its own API, and dijitul has worked with the KashFlow API since around 2011. Our accounting software integration page covers all four.
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