CPA Field Guide / US tax & accounting
No pay-to-list

CPA & accounting software with an open API

How open a tool is to integration decides how much it locks you in. Here is every tool in this guide sorted by that — the ones with a self-serve public API first.

Open API — self-serve

You can generate an API key yourself and build against it, no approval needed.

Gated API

An API exists, but access needs approval, a partner program, or a higher plan.

Zapier only

No direct API; they connect to the rest of your stack through Zapier.

FAQ

Which CPA practice-management tool has the best API?

Karbon offers the most complete self-serve public API with webhooks; TaxDome also issues self-serve keys. Both let you build directly, without a partner agreement.

What does an open API mean for accounting software?

It means you can generate an API key yourself and integrate without vendor approval — the lowest-friction way to connect a tool to the rest of your firm's stack.

Independent and no pay-to-list: only shipped capabilities (reviewed July 2026), maintained by the team behind DueDateHQ and held to the same standard as every other tool here. How this guide works →

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