You'll work primarily with TypeScript, Node.js, and PostgreSQL on GCP, designing and building scalable backend systems. The team develops and maintains a robust investment platform that powers features like mutual funds, bonds, and family investment tools.

Koinly★3.0 (1)· London

Work with React 19, TypeScript, TanStack (Router, Query, Table), Radix UI, Mantine, Tailwind CSS v4, Vite, Vitest, Storybook, Highcharts, Sentry, Bun, and RabbitMQ on a data platform that reconciles crypto transactions and tax obligations for Koinly’s web application, with a React Native mobile app joining scope later.

Backend Nest.js and TypeScript; frontend Angular (v20) and Ionic; Azure CI/CD for multiple daily deployments. You maintain the ZigZag Puppy Training mobile app (iOS and Android), shipping full-stack features and guiding backend architecture and API design.

Senior software engineers work with Nest.js, TypeScript, Angular, Ionic, and Azure CI/CD on the ZigZag dog-training mobile app (iOS/Android). This full-stack individual contributor role leads backend design, APIs, data modelling, and infrastructure decisions on a small, collaborative team.

You will work with Nest.js, TypeScript, Angular (v20), Ionic, and Azure CI/CD pipelines to build and maintain the Zigzag puppy training mobile app across iOS and Android, handling the full stack with a backend focus on APIs and data modelling.

You will work with React Native, TypeScript, React Navigation, REST APIs, CI/CD, and automated testing. This is a greenfield role building a new cross-platform mobile application for enterprise customers at a fast-growing SaaS company.

You will build production mobile apps for iOS and Android using React Native, TypeScript, and integrate AI, natural-language features, Swift, Kotlin, and Python. The venture-backed startup creates AI-powered software that replaces manual workflows for industrial and operational teams.

You will own an existing production React/TypeScript application across web, iOS, and Android, integrating with Python/FastAPI backends and managing CI/CD pipelines. The team builds a computer-vision platform that turns video data into actionable insights. You will drive frontend architecture on a small, collaborative engineering team.

Work with React Native, TypeScript, AI-assisted engineering tools, analytics, feature flags, and monitoring tools. Build and ship mobile experiences for an AI-powered FinTech platform that transforms data infrastructure and workflow automation across global financial markets. Own mobile initiatives as a hands-on senior engineer.

Foundation Partners Group★2.6 (165)· London

Typescript, Python, full-stack web development, frontend focus, offline support, observability, and testing across devices. You will build and scale consumer-facing production web applications for Flok Health, an AI-native healthcare company transforming care for MSK pain.

You will work with Solidity, React, Node.js, TypeScript, GraphQL, React Native or Flutter, and Ethereum or Binance Smart Chain. This consulting company builds web, mobile, and Web3 applications with blockchain integration.

Omaze★4.3 (6)· London

You will own mobile features across a TypeScript, React Native, and Expo codebase, writing native code in Swift (iOS) or Kotlin (Android) when needed and using EAS build and deployment workflows. Omaze gives its community the chance to win luxury homes while raising money for UK charities.

React, Node.js, AWS, TypeScript, React Native, RESTful and GraphQL APIs, serverless architectures, CI/CD, PostgreSQL, DynamoDB, and AI tools such as Claude and GitHub Copilot. Build and ship digital products for a pre-IPO challenger bank serving mass affluent clients, owning full-stack work from architecture to production monitoring.

Build and enhance customer-facing and internal web applications using Next.js, React, TypeScript, and GraphQL. The Web Engineering team creates the web experiences powering customer acquisition, servicing, and internal tools at Zopa.

Proton★5.0 (1)· London

You will work daily with C#, TypeScript, and Rust, also providing bindings for Swift and Kotlin, using tools like Grafana, Prometheus, Sentry, GitLab CI, and Playwright. The Drive Foundation team builds the SDK that powers Proton Drive, ensuring cross‑client consistency and serving as the backbone for the encrypted cloud storage service.

Smarkets★5.0 (2)· London

Build web and mobile apps with Next.js, React, React Native, TypeScript, Redux, React Query, WebSockets, and REST APIs, using Figma for design and GitLab with Kubernetes for DevOps. You will craft polished interfaces for Smarkets, which operates one of the world’s most sophisticated prediction markets for sports and political events.

Build full-stack mobile applications using React, Node.js, AWS, React Native, TypeScript, JavaScript, GraphQL APIs, serverless architectures, CI/CD, PostgreSQL, and DynamoDB. You'll design, develop, and ship digital products for Monument, a challenger bank serving the mass affluent, with ownership from architecture to production.

You will work with Kotlin, Spring, React Native, TypeScript, PostgreSQL, AWS, Terraform, and Ansible to build backend features for a cross-border fintech mobile app that serves emerging markets. The role focuses on developing consumer-facing features end-to-end in a fast-growing engineering team.

Depop★4.4 (61)· London

This Senior Backend Engineer role uses Scala (primary), TypeScript, Python, Play Framework, Kubernetes, PostgreSQL, DynamoDB, and Kafka. The Shipping Experience team builds and evolves the end-to-end shipping journey for buyers and sellers on Depop’s peer-to-peer circular fashion marketplace.

Build production-grade cross-platform apps with React Native, TypeScript, and native modules (Swift/Kotlin). You'll design offline-first mobile workflows with AI integration (LLMs, agents) and build backend services (Python a plus). The team is removing manual barriers in industries like aerospace, healthcare, and energy.

Work with Kotlin (90%+) and Java, using Android Studio, Jetpack Compose, Coroutines/Flow, MVVM, Webviews, and modular architectures. You'll build and test major new features for the Guardian's award-winning Android app, while improving and maintaining existing functionality. You'll take a leadership role on projects and mentor other developers.

Proton★5.0 (1)· London

Join Proton's Inbox Desktop team to rebuild the Proton Mail Desktop App, Mail Bridge and Export tool using a cross-platform Rust stack. You'll work with Golang, C++, Qt, JS, TypeScript, React, Electron and standard dev tools (Git, GitLab CI, Jira). You’ll take technical ownership of the Windows and Linux desktop clients within a cross-functional team of about 60 engineers.

Proton★5.0 (1)· London

As a Senior Front End Engineer on the Standard Notes team, you will work with JavaScript, TypeScript, React, ES6, Playwright, Jest, and Grafana. The team builds a secure note-taking and productivity platform, developing features like encrypted search and cross-platform sync using end-to-end encryption. All Standard Notes codebases are open source.

Proton★5.0 (1)· London

Engineering Directors at Proton set technical direction and work with PHP (Symfony), Rust, Python, Swift, Kotlin, Jetpack, Typescript, React, C#, SQL, Redis, MySQL, and Ceph across mobile, desktop, web, and backend platforms. They lead engineering for one of Proton’s existing or upcoming products—such as Proton Mail, VPN, Calendar, Drive, or Pass—which provide private, secure, open-source tools to over 100 million users. The role involves managing a team of managers and driving DevSecOps practices.

Funding Circle★3.5 (53)· London

You will work with React Native, React.js, TypeScript, Firebase, Gradle, XCode, REST APIs, and CI/CD for app releases on iOS and Android. The role involves building and scaling a mobile app for Funding Circle’s fintech platform that uses data to provide fast funding to small businesses.