react js developer jobs in Southampton

You must speak, write and be able to understand fluent English. - Deep knowledge and regular usage of Firebase suite, especially Firestore. - Strong proficiency in TypeScript and modern JavaScript (ES6+).

You must enjoy constantly learning and researching to improve your level of expertise.

🚀 Senior Full-Stack Engineer – TypeScript / React / AWS 💰 Up to £80k | Fully Remote (UK) 💻 Tech Stack: TypeScript, Node.js, React.js, AWS ✅ Slight backend lean We’re on the hunt for a hands-on Senior Engineer to join a fast-moving team delivering real, production grade systems. This isn’t R&D or proof-of-concept work, they’re shipping cloud-native, AI-enabled products that customers actually...

Senior Full Stack Engineer | Up to £110K | One of the UK's fastest growing AI platforms | UK Remote | React/Node/TypeScript I am currently working with one of the fastest-scaling platforms in the creator economy which is a creator-first, AI-powered product that enables creators around the world to directly monetise their audiences. Every system you build will operate at serious global scale. 🎯...

You must speak, write and be able to understand fluent English. Strong proficiency in TypeScript and modern JavaScript (ES6+). Familiarity with Expo, React Navigation, Reanimated and Vision Camera. Understanding of mobile app development best practices, including release automation and performance optimisation.

About Prighter Prighter is a fast-growing LegalTech company building productised services and SaaS solutions for compliance with data protection as well as AI & digital governance regulations. With the mission to enable companies around the world to comply with regulatory requirements for their digital business, our services and SaaS solutions guide our global clients through the increasingly...

Senior Backend Developer (.NET | AI-First SaaS Platform) Compensation: Competitive, based on location and experience Location: UK or Turkey (Hybrid – Office & Remote) Keepnet is an AI-driven SaaS platform experiencing strong, sustained growth in the UK with growing global momentum, helping organisations manage human cyber risk at scale. With Agentic AI live in production, Keepnet runs...

About Aero A digital experience company, we sit at the intersection of insights, creativity and technology, crafting digital experiences that transform business performance. We’re a small, fully remote team with big ambitions. We work hands-on with our clients, giving our teams genuine ownership of their work. Every project you touch will be seen by thousands of people and will directly...

On a mission to help people who have been diagnosed with chronic kidney disease, this start-up are looking to bring on a Senior TypeScript Developer, who’s fully embraced AI-assisted development. Their mission is to make life better for people suffering from kidney disease by building one of the first algorithm-based behavioural change programmes. The application that does this brings together...

You will be working in a fast-paced environment to develop new website themes and add new features in a complex Next. js-based codebase (including a CMS). This is a great opportunity for the right person to take on a challenging and broad role. Homeflow is operating on a fully remote basis but occasional travel will be required for our company meet ups (bi-annually at most in the UK).

You will have meaningful influence over how reliability, security, and operational standards are defined and implemented.

You will take a senior, hands-on role in shaping the platform and guiding technical direction, while still remaining close to the work. Key areas of responsibility include:

Senior/Lead Software Engineer – Fully Remote (UK) A global B2B SaaS technology business is building out its European engineering hub and is hiring multiple Senior / Lead Software Engineers (JavaScript) to develop and enhance a mission-critical platform used internationally. These are hands-on individual contributor role with strong ownership — ideal for engineers who enjoy building high-quality...

SOFTWARE ENGINEER REMOTE (OPTION TO RELLOCATE) £110K + EQUITY THE COMPANY This innovative AI startup is redefining safety and reliability in AI models. While competitors like GPT and DeepMind struggle with hallucinations and illegal content generation, this company adds safety control layers to ensure AI outputs are trustworthy and compliant. Working with high-profile, they’re building AI...

You should be comfortable with most of our core technologies:

Senior Full-Stack Engineer Fully Remote | UK Salary: Up to £100,000 Neulinx have partnered with a fast-growing B2B SaaS product company to hire an experienced Senior Full-Stack Engineer to join their engineering team at an important stage of growth. This is a hands-on senior role suited to someone who enjoys building high-quality product features, taking ownership of complex systems, and...

You will have the opportunity to be part of a global high-performing dynamic software team, doing what you do best. The role is focused on designing and building the best solutions for our users in over 120 countries, whilst maintaining best practices in software development.

Full Stack Engineer (Java, React, AI/ML/LLM/SDK) – Cutting-Edge Series B scale up Location: Remote EU - Spain Salary: £70K - £110K About: We are seeking a Full Stack Engineer with a proven track record in building and scaling applications powered by Large Language Models (LLMs). This role requires deep expertise in Java, React, and modern AI/ML development, including LLM frameworks, SDKs, and...

Market Design Lead – Switching & Registration Who Are RECCo? We are an independent, non-profit organisation responsible for the Retail Energy Code — a key part of how the GB retail energy market is regulated. But we don’t just manage rules. We look ahead, not just react, helping the market change in the right way. We deliver secure digital services, clear governance, and practical solutions...

You will work on challenging, real-world technical problems, from early-stage research through to fully released products, contributing to solutions that operate in demanding and high-assurance environments.

You will be part of a small, highly capable engineering team responsible for designing and delivering secure, high-reliability solutions.

You will design, develop, and maintain our platform’s backend infrastructure, focusing on multi-tenant architectures, security, and efficient LLM integration. This role requires a strong understanding of Python web frameworks, cloud services (particularly AWS), and modern AI approaches including working with agentic architecture.

Senior Full Stack Engineer Remote (UK) | Full time London office available for optional in person collaboration We’re looking for an experienced Senior Full Stack Engineer to join a small, highly skilled team building a next generation Financial Services Regulatory Compliance platform. This is a hands on role where you’ll work across the stack, leading frontend development with React and...