About Sphere
Sphere is betting that global indirect tax can be handled by an AI engine that continuously reads and codifies tax law itself. Its system monitors more than 100 tax authorities and powers end-to-end registration, filing, and remittance for software companies selling worldwide.
A Y Combinator (W22) company, Sphere raised a $21M Series A led by Andreessen Horowitz in November 2025 ($71.5M total). Its customer list skews AI-native: Lovable, Replit, Windsurf, Deel, and ElevenLabs.
A proprietary AI tax engine continuously codifies and monitors tax law across 100+ authorities, powering automated global registration, filing, and remittance without manual research.
Highlights
- Raised a $21M Series A led by a16z (November 2025); $71.5M total
- Customers include Lovable, Replit, Windsurf, Deel, and ElevenLabs
- Y Combinator W22 batch
Third-party reviews
Early reviewers highlight strong integrations, simplified global compliance, and flat-rate-per-region pricing.
Read on G2Ratings belong to the cited platforms and change over time — last checked August 2026. TaxAIs does not collect its own reviews; follow the links above for current scores and full review text.
More in Sales tax, VAT & GST
Avalara
avalara.comThe default name in sales tax automation, now deploying Avi — a network of AI agents that determine, file, and research tax autonomously.
Vertex
vertexinc.comEnterprise indirect tax since 1978 — the O Series engine plus a generative Copilot, and a strategic stake in AI-native Kintsugi.
Fonoa
fonoa.comBuilt by ex-Uber operators: a global tax OS for digital businesses — ID validation, determination, e-invoicing, and returns in 190+ jurisdictions.