Can you help me choose between QuickBooks Online API, Xero API, and Codat for syncing invoices and financial data?

Yes — here’s a practical way to choose between QuickBooks Online API, Xero API, and Codat for syncing invoices and financial data.

Short version

• Choose QuickBooks Online API if you only need QuickBooks and want the most direct, lowest-middleman integration.
• Choose Xero API if you only need Xero and your customer base is Xero-heavy.
• Choose Codat if you need one integration layer for multiple accounting platforms and want to avoid building and maintaining separate connectors yourself.

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How they differ

1) QuickBooks Online API

Best for: QuickBooks-only integrations

Pros

• Direct access to QuickBooks data and workflows
• No middleware/vendor dependency
• Good if your users mainly use QuickBooks
• Full control over sync logic

Cons

• Only covers QuickBooks
• You’ll need to handle auth, rate limits, field mapping, and edge cases yourself
• If you later want Xero or others, you’ll need another integration

Use it if

• Your product primarily serves QuickBooks users
• You want maximum control
• You can invest in building and maintaining the integration

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2) Xero API

Best for: Xero-only integrations

Pros

• Direct integration with Xero
• Solid accounting objects for invoices, contacts, payments, etc.
• Good if your customers are in regions where Xero is common

Cons

• Only Xero
• You still need to manage sync logic and API quirks
• If you want multi-accounting support later, you’ll add more work

Use it if

• Your target market strongly prefers Xero
• You only need Xero support
• You want direct platform integration

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3) Codat

Best for: Multi-platform accounting sync

Pros

• One API for many accounting systems
• Faster to launch multi-provider support
• Normalized data model can simplify invoice/financial sync
• Helpful if you want to support QuickBooks + Xero + others

Cons

• Additional cost
• You depend on a third party for the abstraction layer
• You may lose some low-level platform-specific control
• Normalization may not fit every edge case perfectly

Use it if

• You need to support multiple accounting systems
• You want to minimize maintenance
• Speed to market matters more than deep platform-specific control

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Decision matrix

Criteria	QuickBooks API	Xero API	Codat
Single-platform direct access	Excellent	Excellent	Good
Multi-platform support	Poor	Poor	Excellent
Implementation speed	Medium	Medium	Fast
Maintenance burden	Higher	Higher	Lower
Control over edge cases	High	High	Medium
Vendor dependency	Low	Low	Higher
Best for invoice sync	Good	Good	Very good for cross-platform

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For syncing invoices specifically

If your goal is to:

• create invoices,
• pull invoice status,
• sync payments,
• map customer/contact data,
• keep financial totals aligned,

then the main question is not “which API is best?” but:

Do you need one or many accounting platforms?

• One platform: use the native API.
• Several platforms: use Codat.

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Recommended choice by scenario

Pick QuickBooks Online API if:

• 80–90% of your customers use QuickBooks
• You need deep QuickBooks-specific behavior
• You have engineering resources to maintain the integration

Pick Xero API if:

• Xero is your primary customer base
• You only need Xero support
• You want direct, first-party access

Pick Codat if:

• You need QuickBooks + Xero support now or soon
• You want to avoid duplicate connector work
• You care about scaling integration coverage quickly

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My practical recommendation

• If you’re building a single-accounting-platform product, use that platform’s API directly.
• If you’re building a B2B SaaS product that needs accounting sync across many customers, start with Codat unless you have a strong reason not to.

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If you want, I can also help you choose based on:

1. your expected customer mix,
2. whether you need read-only vs read/write sync,
3. invoice/payment sync complexity,
4. budget and implementation timeline.