> Markdown version of [/jobs/ext/2486603-mid-level-to-senior-software-engineer](https://www.wearedevelopers.com/jobs/ext/2486603-mid-level-to-senior-software-engineer). Every page supports `.md` or `Accept: text/markdown`. Links point to the HTML versions so they work for humans too. Agent guide: [/agents.md](https://www.wearedevelopers.com/agents.md). --- # Mid-level to Senior Software Engineer - **Company:** Plasma - **Location:** London, UK - **Experience:** Experienced - **Salary:** £150,000.0 - £200,000.0 - **Contract:** Permanent contract - **Skills:** Clean Code Principles, Application Programming Interfaces (APIs), Mobile Application Development, Code Review, Node.Js, TypeScript, ReactJS, Backend, Build Management, React Native, Front End Software Development - **Published:** August 26, 2026 - **Apply:** https://uk.indeed.com/viewjob?jk=a29894a22aadb4e3 ## About the Role * A mid-level to senior, hands-on engineer with a track record of shipping and owning production, fullstack systems end-to-end. * Strong product sense: you notice when something feels slow, confusing, or untrustworthy, and you fix it without being asked. * Comfortable taking product surfaces from zero to one, and then scaling them without losing clarity or performance. * Strong judgment on tradeoffs: speed vs. polish, abstraction vs. control, simplicity vs. flexibility. * You communicate clearly, write clean code, and can lead through technical and product decisions. * Experience building product-facing or client-side systems at scale * You make decisions based on data and use data to ground whether solutions work Nice to have * Experience with React Native or native mobile development. * An eye for interaction and motion design, and a track record of partnering closely with product designers rather than just implementing their files. * Fintech, banking, or crypto-native background. * You've been a founder or early employee at a fast-paced, high agency startup ## Description * Consumer owns the core Plasma One product experience - onboarding, activation, retention, rewards, tiers, trading, earn, and account management. The team is responsible for growing funded users, engagement, balances, spend, and long-term retention. * Payments owns the financial infrastructure that powers Plasma - accounts, ledgers, funding, payouts, card issuing, reconciliation, payment orchestration, and currency/rail integrations. The team is responsible for the reliability, scalability, and economics of moving and storing money. * Business owns the Plasma experience for companies - the operating account for businesses that work globally: onboarding, receiving, holding, and sending money across borders, corporate cards and spend management, and the roles and approvals that keep teams in control of company money. The team is responsible for taking the product from its first business customers to general availability, and for growing the businesses that run on Plasma., Plasma's product is where all of this becomes real to people: the app they open every day, the balances they watch grow, the card they spend with. We're looking for a mid-level to senior, fullstack engineer to join one of Plasma's engineering teams and own the product and client-side surfaces that team is responsible for. Our stack is TypeScript across the board - Node.js on the backend and React + React Native for the frontend You'll report into your team's eng lead and partner closely with your product lead to ship production-quality experiences from the API down to the pixel. The Work * Build and own your team's product and client-side surfaces end to end, in React and React Native - from the API down to the pixel. * Care as much about how a screen feels as whether it's correct: performance, responsiveness, and the small interactions that make the product feel trustworthy with someone's money. * Design and build the systems: state management, data schema design and robust handling of real financial data * Partner closely with product and design at the concept level, so the experience and the implementation move as one thing, not two departments. * Own reliability: graceful handling of failures, retries, and edge cases in a product where mistakes cost people real money. * Raise the bar on engineering quality within your team: architecture, testing strategy, performance budgets, and code review. * Mentor other engineers and drive technical clarity on the product side of your team. * You have very high agency and don't wait to be told a problem to work on and proactively find new problems to solve ## Related Videos - [Developing the Backend with Stefan Lingler, CTO at Shpock](https://www.wearedevelopers.com/videos/100360-developing-the-backend-with-stefan-lingler-cto-at-shpock) - [Watch Tests Go Brrrr! : Getting Started with Cypress in ReactJS](https://www.wearedevelopers.com/videos/282-watch-tests-go-brrrr-getting-started-with-cypress-in-reactjs) - [Stop using Node.js like in 2020! What changed and what you can do today with Node.js](https://www.wearedevelopers.com/videos/100011-stop-using-node-js-like-in-2020-what-changed-and-what-you-can-do-today-with-node-js) - [Multiple Apps, Millions of Users: Scaling React Native in Production](https://www.wearedevelopers.com/videos/100313-multiple-apps-millions-of-users-scaling-react-native-in-production) - [Meet Your New BFF: Backend to Frontend without the Duct Tape](https://www.wearedevelopers.com/videos/682-meet-your-new-bff-backend-to-frontend-without-the-duct-tape) - [Nest.js - TypeScript in the backend can also be clean](https://www.wearedevelopers.com/videos/1033-nest-js-typescript-in-the-backend-can-also-be-clean) ## Related Articles - [React Developer Salary [2023]](https://www.wearedevelopers.com/magazine/198-react-developer-salary-2023) - [Software Engineer Salary London](https://www.wearedevelopers.com/magazine/252-software-engineer-salary-london) - [16 Best Free React UI Libraries in 2025](https://www.wearedevelopers.com/magazine/148-16-best-free-react-ui-libraries-in-2025) - [Fully Remote Software Engineer Jobs](https://www.wearedevelopers.com/magazine/447-fully-remote-software-engineer-jobs) - [Frontend Developer Salary in The UK](https://www.wearedevelopers.com/magazine/233-frontend-developer-salary-in-the-uk) - [What’s the Difference between a Junior, Mid, and Senior Developer?](https://www.wearedevelopers.com/magazine/238-what-s-the-difference-between-a-junior-mid-and-senior-developer)