Senior Full Stack Engineer

Sphere Digital Recruitment; Greater London; On-site; GBP 166,000 - 212,000; Full time

Job summary

Sphere is seeking a Senior Full Stack Engineer to own and build out new product lines (input tax, withholding tax, e-invoicing, tariffs) and critical platform components. You will contribute to scaling the AI-native compliance platform and drive ARR growth with end-to-end ownership.

You will ship mission-critical features, manage a dedicated component, and collaborate with clients to improve filing generation and submission speed, while mentoring other engineers in your areas of expertise.

Qualifications

• Proven Python/Django backend experience in data pipelines.
• Comfortable with React to support frontend tasks as needed.
• Strong attention to detail and reliability with high‑volume data.

Responsibilities

• Develop and own mission-critical features, including filing infrastructure.
• Lead end-to-end development of new product lines for the platform.
• Collaborate with customers to optimize core components and performance.

Skills

Python

Django

React

Tools

Django ORM

Job description

About Sphere

Every breakthrough in trade infrastructure has followed the same pattern: reduce a transaction cost, expand the market. Containerization for goods. SWIFT for money. Stripe for payments. Compliance is one of the last and largest — and the hardest, because trade rules aren't data to be looked up. They're a complex adaptive system with 190+ sovereign jurisdictions, in different languages, changing constantly, reacting to each other.

Sphere built the system that solves it. Our AI (TRAM) ingests global trade law, interprets it, resolves conflicts across jurisdictions, and produces compliance determinations more reliable than human experts. We handle the entire lifecycle — calculation, registration, filing, remittance — at millisecond latency with zero downtime.

• Backed by a16z and YC. $21M Series A, 30%+ month-over-month growth, customers include ElevenLabs, Replit, Deel, Runway, and Lovable.
• Small team, global surface area. Everyone owns a domain that would be a full team at a larger company. San Francisco, in office.
• The problem keeps compounding. Expanding into input tax, withholding, e-invoicing, tariffs — each multiplies the complexity. Tens of millions of transactions today, billions ahead.

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 A I / 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'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)

Compensation Range: $220K - $280K