Senior Fullstack Engineer in London

Join Tether and shape the future of digital finance. At Tether, we’re not just building products; we’re pioneering a global financial revolution. Our cutting-edge solutions empower businesses—from exchanges and wallets to payment processors and ATMs—to seamlessly integrate reserve-backed tokens across blockchains. By harnessing the power of blockchain technology, Tether enables you to store, send, and receive digital tokens instantly, securely, and globally, all at a fraction of the cost. Transparency is the bedrock of everything we do, ensuring trust in every transaction.

Innovate with Tether:

• Tether Finance: Our innovative product suite features the world’s most trusted stablecoin, USDT, relied upon by hundreds of millions worldwide, alongside pioneering digital asset tokenization services.
• Tether Power: Driving sustainable growth, our energy solutions optimize excess power for Bitcoin mining using eco-friendly practices in state-of-the-art, geo-diverse facilities.
• Tether Data: Fueling breakthroughs in AI and peer-to-peer technology, we reduce infrastructure costs and enhance global communications with cutting-edge solutions like KEET, our flagship app that redefines secure and private data sharing.
• Tether Education: Democratizing access to top-tier digital learning, we empower individuals to thrive in the digital and gig economies, driving global growth and opportunity.
• Tether Evolution: At the intersection of technology and human potential, we are pushing the boundaries of what is possible, crafting a future where innovation and human capabilities merge in powerful, unprecedented ways.

Why join us? Our team is a global talent powerhouse, working remotely from every corner of the world. If you’re passionate about making a mark in the fintech space, this is your opportunity to collaborate with some of the brightest minds, pushing boundaries and setting new standards. We’ve grown fast, stayed lean, and secured our place as a leader in the industry. If you have excellent English communication skills and are ready to contribute to the most innovative platform on the planet, Tether is the place for you. Are you ready to be part of the future?

About the job: You will work across the JavaScript and TypeScript layer of our local AI stack. Depending on the project, you might build user-facing applications (mobile or desktop) or contribute to the platform layer that bridges our C++ inference engines with the app ecosystem. Whether you’re crafting polished product experiences or building the SDKs and bindings that other developers rely on, you’ll be helping make local AI truly usable. You’ll be contributing to QVAC, our local AI stack built to bring fast, private AI directly to user devices. This role suits engineers who thrive in a full-stack JS environment and enjoy working close to both product and platform to turn powerful AI capabilities into real-world applications.

Responsibilities:

• Own React (Expo/Electron) app development with clean, modular architecture.
• Build UI using modern React stack (TypeScript, RN Navigation, Zustand/Recoil/Jotai).
• Implement local first / local only apps.
• Integrate mobile apps with distributed systems, local inference, and p2p layers.
• Strong experience with REST/WebSockets, async flows, and secure data storage.
• Ability to build native modules (iOS/Android) when needed (with some help).
• Good understanding of offline-first systems, caching, and performance.
• Comfortable integrating SDKs (payments, crypto, AI models, etc.).
• Write reliable code: unit tests, E2E tests (Maestro/Appium/Playwright).
• Experience with TypeScript across stack (frontend + backend).
• Bonus: experience with distributed/P2P APIs, on-device ML, cryptography.

5+ years of experience in Fullstack development. Expert-level proficiency in Node.js/JavaScript for backend development and React frontend framework. Experience with performant data handling on constrained devices (via SQLite or similar). Proven experience building and scaling distributed systems or event-driven architectures. Experience with containerization technologies (Docker) and orchestration platforms (Kubernetes). Proficiency with databases, and a deep understanding of data modeling and optimization. Solid understanding of networking, security principles, and best practices for production systems. Experience with real-time data streaming and RPC implementations. Ability to work independently in a remote environment and communicate effectively across time zones.

Nice to have:

• Experience with peer-to-peer technologies (Hyperswarm, libp2p, WebRTC) or similar distributed communication protocols.
• Familiarity with AI/ML inference APIs and OpenAI-compatible endpoints.
• Previous experience building AI SaaS or PaaS platforms.
• Knowledge of GPU resource management and ML framework infrastructure.
• Understanding of WebAssembly or edge computing paradigms.
• Contributions to open-source projects in relevant domains.

Important information for candidates: Recruitment scams have become increasingly common. To protect yourself, please keep the following in mind when applying for roles:

• Apply only through our official channels. We do not use third-party platforms or agencies for recruitment unless clearly stated. All open roles are listed on our official careers page.
• Verify the recruiter’s identity. All our recruiters have verified LinkedIn profiles. If you’re unsure, you can confirm their identity by checking their profile or contacting us through our website.
• Be cautious of unusual communication methods. We do not conduct interviews over WhatsApp, Telegram, or SMS. All communication is done through official company emails and platforms.
• Double-check email addresses. All communication from us will come from emails ending in @tether.to or @tether.io.
• We will never request payment or financial details. If someone asks for personal financial information or payment at any point during the hiring process, it is a scam. Please report it immediately.
• When in doubt, feel free to reach out through our official website.