Tax and compliance software: 9 vendors compared

Tax technology splits between the indirect tax tools finance teams use and the preparation tools firms use. Avalara is the incumbent, preparing to return to the public market; Anrok, Numeral, Sphere, Zamp and Kintsugi raised more than $300 million between them to sell sales tax compliance to software and e-commerce companies; Fonoa bought PwC's platform; April embeds tax filing into other apps. Every vendor below has a full profile.

The vendors

Startups first, ordered by funding raised, then the established vendors they compete with

FonoaStartup · $190m raisedGlobal indirect tax automation for digital businesses: tax ID validation, tax determination, e-invoicing and returns across more than 100 countries, built by three former Uber tax and product staff.→AnrokStartup · $109m raisedSales tax and VAT compliance built for software companies: nexus monitoring, calculation, registrations and filings across the US and international markets, used by Anthropic, Notion and Cursor.→AprilStartup · $78m raisedEmbedded tax infrastructure for US financial platforms: filing, forecasting and tax transcript access built into banks, payroll and investing apps, with an AI engine that pre-fills federal and state returns.→SphereStartup · $72m raisedAI-native global tax compliance for companies selling across borders: sales tax, VAT and GST registrations, calculations, filings and remittance, priced at a flat $100 per region per month.→NumeralStartup · $58m raisedAI-native sales tax and VAT compliance for e-commerce and software companies: registrations, calculation, filing and remittance across more than 70 countries, valued at $350m two years after founding.→ZampStartup · $44m raisedManaged sales tax compliance sold direct and through accounting firms: nexus tracking, registration, calculation and filing across 12,000-plus US jurisdictions, with an operating system for firms that white-label it.→KintsugiStartup · $35m raisedAI sales tax compliance for small and mid-sized businesses: nexus tracking, registrations, filing and remittance, with tax incumbent Vertex as a 10% shareholder after its 2025 investment.→AccrualStartupAI-native tax preparation for firms: agents act as preparers on individual returns, reading K-1s, 1099s, spreadsheets and statements, and plugging into the firm's existing tax engine.→AvalaraThe largest sales tax and indirect tax compliance vendor: calculation, returns, exemption certificates, e-invoicing and cross-border duties for more than 40,000 customers, taken private by Vista for $8.4bn in 2022 and preparing to return to the public market.→

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Updated September 2026 · Part of Accountio’s accounting technology coverage