Senior Full Stack Engineer

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
• Very strong attention to detail. When you work with numbers this is a non-negotiable - it’s not enough to be 99% right.

Nice to have:

• Experience working with large volumes of transaction data. You’ll be getting very familiar with it!
• Experience with Django or Python ORM