OpenTax by Invaro
OpenTax by Invaro: An auditable, open-source tax engine for developers and automation tools. Ranked #16 of 32 in AI Tax Software by our editors (7.0/10); pricing: Free plan; best for developers needing auditable tax engines.
At a glance
- Editor score7.0 / 10
- PricingFree plan
- Best forDevelopers needing auditable tax engines
- Free planYes
- Paid fromFree
- Taxpayer typesBoth
- Facts checked22 Sep 2026
Where it wins
- Deterministic federal and state calculations using exact arithmetic
- Statute citations and Merkle-rooted proof artifacts support verification
- REST, MCP, CLI, and local tools fit AI and developer workflows
Where it doesn't
- It is an engine and developer platform, not a consumer filing product
- Working with structured facts requires a technical implementation
- The Evaluation plan is the only published plan with no-expiry access
Our verdict on OpenTax by Invaro
OpenTax by Invaro is an open-source tax computation engine for developers, AI assistants, accounting firms, and automation tools. It processes structured facts and tax-document data, then supports individual, corporate, and fiduciary calculations across federal and state returns. The product is designed for teams that need tax results they can inspect, cite, and verify rather than a consumer-oriented filing workflow.
Its strongest distinction is auditability. OpenTax uses deterministic calculations with exact arithmetic, attaches statute citations to tax rules and results, and can produce Merkle-rooted proof artifacts for offline verification. It also compiles W-2 and 1099 data into engine facts, with tools for tax-rule search, parameter lookup, and fact verification. These capabilities make it a fit for applications where an AI-generated explanation needs a traceable calculation behind it. Teams seeking a narrower, guided filing experience should look elsewhere.
The platform fit is broad for a developer-focused product. It offers a hosted HTTP/MCP service, REST and MCP interfaces, and local packages including a CLI, MCP server, HTTP host, and browser-safe library. The published Evaluation plan is free with no expiry and includes hosted API and MCP access. OpenTax also connects with AI assistants, coding environments, agent frameworks, and automation tools including Claude, ChatGPT, Gemini, Cursor, VS Code, LangChain, n8n, Zapier, and Make. Choose it when integration, local execution, and verifiable outputs matter; do not choose it if the priority is a conventional end-user tax filing product.
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OpenTax by Invaro pricing
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OpenTax by Invaro fact sheet
| Free plan | Yes |
|---|---|
| Paid from | Free |
| Taxpayer types | Both |
| AI tax guidance | Yes |
| Document import | Yes |
| Deduction finding | Not verified |
| Expert review | Not verified |
| Filing support | Both |
| Return limit | Not verified |
| Deployment | Cloud, Self-hosted |
| Platforms | Web |
| Support | Docs |
| Built for | Small business, Mid-market, Enterprise (editorial estimate) |
| Integrations | 16 integrations: Claude, ChatGPT, Gemini, Perplexity, Cursor, Windsurf … |
| Pricing | Free plan (source) |
| Website | opentax.invaro.ai |
| Facts checked | 22 Sep 2026 |
OpenTax by Invaro integrations
OpenTax by Invaro lists 16 integrations on its own site.
- Claude
- ChatGPT
- Gemini
- Perplexity
- Cursor
- Windsurf
- Zed
- VS Code
- Cline
- Continue
- Raycast
- LangChain
- n8n
- Zapier
- Make
- Vercel AI SDK
Alternatives to OpenTax by Invaro
- TurboTaxA mature US tax filing choice with broad support and paid tiers for complex returns.9.3
- H&R Block OnlineA broad filing service for US taxpayers who want online tools plus human help.9.1
- TaxActBroad U.S. filing coverage with web, desktop, and mobile options.8.8
See all OpenTax by Invaro alternatives →
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Reviewed by iTechGuides Editors · Editorial team · Updated Oct 2026
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