Top Web Developer Jobs in Belfast

Lead the rebuild of Phrase’s multilingual marketing website using Next.js, Storyblok, and Vercel. Own the reusable component library, WordPress content migration, accessibility and performance automation, SEO migration implementation, deployments, monitoring, integrations, and ongoing site development. Serve as marketing’s primary technical website contact and independently manage the live platform across six languages using AI-assisted coding workflows.

Build and operate full-stack features for elastic.co using React, TypeScript, and backend services. Own deployment pipelines, performance monitoring, observability, security vulnerability remediation, production troubleshooting, code reviews, and on-call support in a globally distributed team.

Lead the technical direction, architecture, development, testing, and support of the University of Edinburgh’s Drupal-based web publishing platform. Build complex enterprise features, uphold coding and development standards, troubleshoot problems, and mentor junior and mid-level developers. Work collaboratively in an agile, continuous-improvement environment while contributing to the evolution of large-scale open-source web services.

Drive quality assurance for web features from technical handoff through production release. Responsibilities include test planning, test case creation, functional and exploratory testing, regression, UI/UX, cross-browser, responsive, API, and end-to-end testing. Support releases through build validation and monitoring, document and review tests, collaborate with product and engineering teams, improve QA metrics, and optionally contribute to test automation.

Develop and maintain React-based user interfaces and Java backend services. Write clean, tested code, debug issues, participate in code reviews, collaborate with designers and stakeholders, and assist with database queries while following best practices.

Build and maintain internal and public-facing APIs and services powering the Web App and developer experience. Develop API functionality, Admin API systems, WebSocket and REST behavior, and usage and billing integrations with Stripe. Investigate production issues and security vulnerabilities, write and review tested code, make technical decisions, and collaborate across engineering, Product, and Design teams.

Build and operate large-scale distributed web crawlers that discover, fetch, extract, deduplicate, and recrawl billions of pages. Develop targeted pipelines for audio, video, and multilingual data, transforming web content into training-ready datasets. Create infrastructure and tooling for researchers to request, monitor, evaluate, and explore crawled data, while ensuring reliability, efficiency, compliance, politeness, and rate-limit handling.

Leads frontend architecture and engineering for large-scale consumer web applications. Defines standards, reusable patterns, and headless API architectures using ReactJS, TypeScript, Next.js, and GraphQL. Drives performance, Core Web Vitals, accessibility, security, experimentation, design systems, and global scalability through CDN and edge technologies. Partners cross-functionally, mentors engineers, influences architecture across teams, and guides technical decisions for reliable, accessible, high-performing digital experiences.

The Ruby Engineer will focus on web scraping and browser automation, fix code issues promptly, support customers, and enhance search engine integrations.

Lead design and development of a high-performance Web SDK for device fingerprinting and behavior analytics. Implement algorithms for fingerprints and interaction capture, optimize cross-browser performance, build CI/CD and automated cross-browser tests, ensure data privacy/security, mentor engineers, conduct code reviews, and collaborate with product and QA to deliver scalable, maintainable SDKs.

Design and implement frontend applications using JS, CSS, React, and Flutter. Collaborate on technical specs and contribute to documentation, ensuring user experience and performance.

Looking for developers with e-Commerce platform experience, strong JavaScript skills, and knowledge of HTML/CSS, working on high-profile projects.

Own and develop Unity’s Web runtime, optimizing build size, download, startup, and loading performance. Design and implement low-level improvements across C++, C#, JavaScript, WebAssembly, Emscripten, and LLVM, including multi-threading and progressive asset loading. Collaborate with platform teams, profile and debug across native and browser boundaries, mentor engineers, and establish code quality standards.

Build, design, maintain, and update websites and software applications supporting global language development and Bible translation work. Responsibilities include writing web content, developing with HTML, CSS, JavaScript, APIs, and WordPress, improving SEO, analyzing requirements, supporting users, documenting website management processes, and contributing to product roadmaps. The role requires independent and collaborative work, with travel to development-team meetings and language technology conferences.

Responsible for architecting and taking ownership of complex web projects, mentoring other developers, and optimizing performance and security in a WordPress context.

Ship real open-source integrations and MCP servers to bring SearchApi to agent and automation frameworks. Create PRs, example apps, docs, and integration guides. Stay current with the agent ecosystem, pick high-leverage targets, and work independently to deliver production-ready integrations.

Build and maintain large-scale WordPress platforms, develop reusable plugins and custom blocks, implement features, optimize performance and accessibility, debug and refactor code, collaborate with teams and clients, and take increasing technical ownership on projects.