> Markdown version of [/jobs/ext/2209499-fullstack-developer-blockchain](https://www.wearedevelopers.com/jobs/ext/2209499-fullstack-developer-blockchain). 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). --- # Fullstack Developer (Blockchain) - **Company:** Número De - **Location:** Barcelona, Spain (Remote available) - **Contract:** Permanent contract - **Skills:** Application Programming Interfaces (APIs), Artificial Intelligence, Business Logic, User Authentication, Authentication Protocols, Software as a Service, Data Security, Programming Tools, Internet Communications, Application Data, Next.js, TypeScript, Web Applications, Tailwind, Integration Frameworks, Front End Software Development, Crud - **Published:** August 24, 2026 - **Apply:** https://www.adzuna.es/contact-us.html ## About the Role + 5-10 years of professional fullstack development experience, with a level of seniority allowing you to take ownership of the application back end. + Proven experience working in SaaS environments and delivering production-grade web applications. + Strong hands-on expertise with Next.js, particularly its integrated server-side capabilities such as Server Actions and API Routes. + Solid experience with data access, third-party integrations, authentication, and complex application business logic. + Strong TypeScript skills and practical experience with Tailwind CSS and shadcn. + Good understanding of modern meta-frameworks, with Next.js experience preferred; familiarity with alternatives such as TanStack Start or Nuxt is a plus. + Ability to design and implement clean, maintainable, modular, and scalable code. + Comfortable using AI-assisted development tools as an integral part of the engineering workflow. + Strong autonomy and ownership, with the ability to take responsibility for a significant technical area of a product. + Collaborative mindset and ability to work closely with front-end developers and other technical stakeholders. + Strong remote communication skills and ability to work effectively within a distributed team. + Proactive approach, with a willingness to challenge assumptions and suggest technical or product improvements. + Fluent French is essential, as it is the team's primary working language. + Sufficient English proficiency to communicate effectively in a professional environment. ## Description As a Fullstack Next.js Developer, you'll join a lean, high-performing technology team building and scaling an AI-powered SaaS product with strong market traction. You'll take ownership of the application's server-side layer while also collaborating closely with front-end developers on product delivery. The role offers substantial technical responsibility, from data access and authentication to complex business logic and third-party integrations. You'll work with a modern stack including Next.js, TypeScript, Tailwind, and shadcn, with AI tools integrated into the development workflow. The environment is fast-paced, autonomous, and focused on shipping high-quality software rather than basic CRUD development. This is an opportunity to become a key technical contributor to a growing product while helping shape its continued evolution. Accountabilities: + Own the application back end integrated directly into the Next.js application, including Server Actions and API Routes. + Design and manage efficient data access and the underlying application data layer. + Develop and maintain third-party integrations and authentication mechanisms. + Implement and optimise complex business logic, including credit management, job pooling, and API timing or delay management. + Collaborate closely with front-end developers to support seamless integration and ensure consistent product experiences. + Contribute directly to the product roadmap and deliver features aligned with business and user needs. + Act as a technical contributor who proactively proposes improvements and solutions rather than simply executing predefined specifications. + Write clean, maintainable, robust, and sustainable code that can evolve with the product. + Investigate and address performance challenges to ensure a reliable and responsive application. + Integrate AI-powered development tools into the engineering workflow while applying appropriate technical judgement to their output. + Communicate effectively within a fully remote team and maintain strong alignment across development activities. + Remain adaptable and, when required, contribute to other products within the wider SaaS portfolio. ## Related Videos - [Build and Deploy a Fullstack App with Open Source Tooling](https://www.wearedevelopers.com/videos/775-build-and-deploy-a-fullstack-app-with-open-source-tooling) - [GraphQL + Apollo + Next.js: A Lovely Trio](https://www.wearedevelopers.com/videos/311-graphql-apollo-next-js-a-lovely-trio) - [Rest API Antipatterns](https://www.wearedevelopers.com/videos/100208-rest-api-antipatterns) - [Level up your Angular CSS with Tailwind CSS](https://www.wearedevelopers.com/videos/640-level-up-your-angular-css-with-tailwind-css) - [From Zero to Hero: NextJS 13 and Tailwind CSS for Beginners](https://www.wearedevelopers.com/videos/766-from-zero-to-hero-nextjs-13-and-tailwind-css-for-beginners) - [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) ## Related Articles - [Fully Remote Software Engineer Jobs](https://www.wearedevelopers.com/magazine/447-fully-remote-software-engineer-jobs) - [What’s the Difference Between Frontend and Backend Development?](https://www.wearedevelopers.com/magazine/240-what-s-the-difference-between-frontend-and-backend-development) - [Top-Paying Tech Jobs (with Salaries)](https://www.wearedevelopers.com/magazine/372-top-paying-tech-jobs-with-salaries) - [Fullstack Developer Salary UK](https://www.wearedevelopers.com/magazine/251-fullstack-developer-salary-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) - [Why Upskilling And Reskilling is Important For Developers](https://www.wearedevelopers.com/magazine/428-why-upskilling-and-reskilling-is-important-for-developers)