Senior Full Stack Engineer

The Role

Sphere is looking for senior full stack engineers who will own and build out new product lines (input tax, withholding tax, e-invoicing, tariffs) as well as mission critical parts of the Sphere platform (filing infrastructure, tax engine and AI / agentic related features).

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 on a daily basis.

What You'll Do

Within weeks

• Ship mission critical features that clients will use daily - e.g. filing infrastructure
• Own and manage a feature and drive measurable outcomes
• Work directly with customers like Eleven Labs, Lovable and Deel to improve / optimize that key component of the platform (e.g. improve filing generation and submission speed [x]%)

Within months

• Own the end-to-end development of new products lines that will help build out our AI-native revenue-based compliance platform
• Lead / mentor additional engineers in component areas that you have worked in

Requirements

• 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 Haves

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

Who You Are

You'll thrive here if

• You're a Dog. You've been underestimated, gone through struggle, and never stopped running. You have a chip on your shoulder and enormous drive. You look at Stripe, Deel, and Flexport all punting on compliance and think: good, that means the opportunity is ours. Hunger beats pedigree.
• Early stage is in your bones. You've built things where there's no playbook and nobody handing you the answer. You define the problem instead of waiting for instructions.
• You own it end to end. Give you a goal and you figure out your own path. Small team, global surface area - everyone owns a domain that would be a full team at a larger company. No one tells you how.
• You believe speed and accuracy are both possible. We're building a complex product that requires robustness and 100% uptime, and we have to build at our customers' pace. Move fast. Don't break things. Both.
• Being in the room is a feature, not a cost. Being in SF isn't a policy, it's how the work gets done. The speed and density of collaboration we need doesn't survive over video.

This won't be a fit if

• You need structure handed to you or ambiguity feels draining rather than motivating
• You want to manage people more than own hard problems (we're a flat, experienced team - everyone builds)
• You're used to "good enough" shipping (small errors have outsized impact here)