Senior Full Stack Engineer

About the role

Mission:

Sphere has built the world’s first AI-native tax engine that helps companies like Eleven Labs, Replit, Runway AI, Windsurf (+ many more) automate their sales tax, VAT and GST obligations:

- We're growing rapidly (34%+ MoM revenue growth) and helping the fastest growing tech companies around the world including Eleven Labs, Replit, Windsurf, Fathom, Linktree, Photoroom, Sierra AI, Zed etc

- We’ve spent the last 1.5 years building local rails into tax authorities in both the US and internationally to properly automate compliance processes (no other vendor has done this)

- We're building the world's first AI-native tax engine (which will be the foundation for a broader cross border compliance platform; think Deel for international billing)

- We're well funded by Felicis Ventures and YC

Sphere is looking for a versatile full stack engineer who can jump on different mission critical areas to help accelerate its production - e.g. filing infrastructure, tax engine and new product areas (input tax, withholding tax, e-invoicing).

These areas are key levers towards scaling Sphere and growing ARR, meaning that your work will have a direct impact on the growth of the business

Why this is a massive opportunity:

🌍 Massive TAM: Every business around the world needs this. Compliance isn’t optional.

🌬️ Strong macro tailwinds: Businesses are expanding globally at a faster pace, while tax authorities are cracking down on cross-border compliance, driving urgent demand.

✨ AI advantage: Incumbents can’t scale beyond the U.S.; our AI-native tax engine can.

🔮 Product vision: Indirect tax is just the start; we’re building the Deel for international billing.

What you will do:

Within weeks:

- Ship features related to a key component of Sphere’s platform - e.g. filing infrastructure

- Own and manage this key component, driving measurable outcomes

- Work directly with customers like Eleven Labs, Replit and Windsurf to improve / optimize that key component of the platform (e.g. improve filing generation and submission speed [x]%)

Within months:

- Develop expertise across other key components of Sphere’s platform - e.g. tax engine, new products - to manage and execute improvements in this area

- Lead / mentor additional engineers in component areas that you have worked in

What’s important to us:

- The Dog: Grit > pedigree.

- Ship fast: If it can be done today, do it today.

- Self-starter: No hand-holding

- Accountability: You’ll be held accountable to objective, measurable targets each month.

- In-person: SF only.

Requirements:

- Strong experience in Python . Our core application backend and data pipeline services are built with Python and Django

- While frontend / React may not be your primary focus, you’re not afraid to dive in when needed