Full Stack Software Engineer

This position is listed on behalf of a partner company, who manages all applications and next steps. Our partner is looking for a Full Stack Software Engineer based in Spain. Join a high-growth fintech and cryptocurrency environment where your engineering expertise will help power secure, scalable, and high-volume financial transactions. As a Full Stack Software Engineer, you will build and maintain backend services and frontend applications that support customer-facing products and internal operational workflows. You will work across modern technologies, including Golang, Java, React, Next.js, and TypeScript, taking ownership of features from technical design through production deployment. Your work will contribute to reliable transaction processing, secure authentication, and seamless integrations with third-party services. Collaborating with engineers and other stakeholders, you will help shape architectural decisions and maintain high standards for performance, security, and observability. This fully remote opportunity is suited to an engineer who enjoys solving complex technical challenges and building impactful products in a regulated financial technology environment.

As a Full Stack Software Engineer, you will contribute to the design, development, and maintenance of secure, scalable applications across the frontend and backend, ensuring that features meet business needs and production standards. Design, develop, test, and maintain full-stack features across web applications and backend services. Build and maintain backend APIs supporting customer onboarding, authentication, transaction lifecycles, and operational workflows. Develop and enhance frontend experiences for customer-facing platforms and internal web applications using React, Next.js, and TypeScript. Build backend services using Golang and/or Java within a scalable microservices architecture. Integrate applications with third-party services, external providers, and supporting systems. Implement secure authentication and authorization mechanisms using OAuth 2.0 flows. Work with relational databases, including PostgreSQL, to support reliable data storage and retrieval. Contribute to cloud-based infrastructure and containerized applications within AWS environments. Help maintain application security, performance, reliability, monitoring, and observability. Participate in code reviews, technical design discussions, and architecture decisions to improve software quality and maintainability. Write and maintain clear technical documentation covering application behavior, system architecture, and implementation decisions. Collaborate with engineering colleagues and relevant stakeholders to troubleshoot issues and deliver features from conception to production. Requirements: The ideal candidate is a versatile software engineer with experience across frontend and backend development, strong programming fundamentals, and the ability to build reliable applications in a distributed environment. You should be comfortable taking ownership of technical work, collaborating with other engineers, and applying secure development practices. At least 3 years of professional software engineering experience across frontend and backend systems. Strong backend development experience with Golang and/or Java. Proficiency in Node.js and TypeScript, particularly TypeScript version 5. Experience building modern frontend applications with React and Next.js. Solid understanding of RESTful API design and implementation. Strong SQL skills and practical experience with PostgreSQL. Experience working with AWS cloud services, including S3. Familiarity with microservices architecture and distributed backend systems. Understanding of containerized applications and infrastructure tools such as Kubernetes, Helm, and Terraform. Experience implementing authentication and authorization using OAuth 2.0 flows. Familiarity with application monitoring and observability tools such as Grafana or similar platforms. Experience using Git-based version control workflows and CI/CD pipelines. Ability to debug applications using development environments such as VS Code or Cursor. Strong problem-solving skills, attention to detail, and an understanding of secure, maintainable software design. Ability to communicate technical concepts clearly, participate in code reviews, and contribute to architectural discussions. Comfortable working independently in a remote environment while collaborating effectively with a distributed team. Preferred Qualifications: Understanding of multithreading concepts and Go concurrency patterns, including goroutines. Experience with webhooks and/or WebSockets. Background in software architecture and system design. Familiarity with AI-assisted development tools. Experience in fintech, cryptocurrency, payments, or other regulated industries. Experience developing internal dashboards and operational tools. Additional knowledge of authentication, authorization, and secure system design. Benefits: Competitive salary paid in USD, based on experience. 15 paid vacation days per year. Paid U.S. national holidays. Fully remote work arrangement, with the original listing specifying eligibility to work from anywhere in Latin America or Europe. Opportunity to build products supporting high-volume financial transactions within the fintech and cryptocurrency industry. Collaborative, high-trust working environment that values engineering ownership and technical judgment. Opportunity to work with modern technologies across backend development, frontend applications, cloud infrastructure, and security.