Senior​/Lead Software Engineer

London
· Hybrid, 3 days a week in the office
· Senior £95 - 125k / Lead £125 - 155k + share options

We're Stream, the world's first social impact unicorn.

More than four million workers use Stream to get a fairer deal with their money. We reach them through 2,000+ employers, including Greene King, Bupa, Burger King, Asda and the NHS, and it all runs through one simple app where people can earn, learn, save, spend and borrow on terms that actually suit them.

We're VC-backed, growing fast and making waves with our financial wellbeing products. We operate under a social charter that holds us accountable: every product we create has to measurably improve financial wellbeing. Moving money for millions of people, at pace, leaves no room for getting it wrong. That's what makes the work worth doing.

• The agent types; you decide. Every engineer gets company-paid Claude Code, and agents write most of our code. There are usage caps, but they're guardrails rather than limits: hit one and we'll raise it. Typing time has gone down and decision density has gone up. So we hire for judgement: what to build, what to cut, when to step in and when to let the agent run.
  
  You own every line that ships.
• A small team with a big footprint. Around 45 people across product and engineering, in small cross-functional pods, serving millions of people in the UK and US. Your work is visible, and it matters.
• Engineers pitch the work. Anyone, at any level, can write an RFC, and good ones get built: our engineers wrote more than 30 in August and September alone. In January one of our engineers proposed connecting our Figma design system to Claude Code, so agents build screens from our real components instead of guessing. Two months later it was live in the UK app.

The team you join depends on your experience and where you'll have the most impact. Most of the work is making proven products better for millions of people. Some of it is greenfield.

• Flex Pay: our earned wage access product in the UK and US. Simple, trusted experiences built on payroll integrations and money-moving services at scale.
• Credit: responsible workplace loans, covering eligibility, decisioning, servicing and repayment, with real regulatory rigour. Live in the UK and expanding in the US.
• Wealth: our emerging workplace savings product. It's early-stage, with plenty of room to shape it.
• Benefits & Discounts: helping employees' money go further through benefits and everyday savings, powered by partner integrations.
• Integrations: working with our Delivery team to connect new employers' payroll and workforce systems so they can launch on Stream.
• Internal tools: the tools that help Stream teams give clients and their employees a better experience.

• Payroll data from dozens of providers. Every employer runs pay differently:
  Workday, Zellis, ADP, Sage, Fourth, even servers in a customer's own building. We turn all of it into an accurate, up-to-date figure for what each person has earned, because that figure is what they can draw.
• Money across rails. Faster Payments, SEPA and US payment rails, direct debits and card repayments, across several banking providers. When a bank's API times out, the payment may still have gone through; retry blindly and someone gets paid twice. Every penny has to reconcile.

• Value, Speed, Simplicity, in that order. Everything we build is tied to a real user need. We prefer short feedback loops to polished first attempts. We build the smallest thing that works.
• Stack:
  Python (Flask), Postgres, Celery and AWS (ECS, Lambda, SQS) on the backend;
  React and Type Script across web and mobile;
  Git Hub Actions for CI/CD. Experience with our stack helps,…