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España
Remote only
Not Available
This position is listed on behalf of a partner company, who manages all applications and next steps. Our partner is looking for a Sr. Full-Stack Software Engineer based in Spain.
Join an AI training project where your full-stack engineering expertise will help improve the quality, reliability, and performance of advanced AI-generated software solutions. You will work on challenging development tasks involving application architecture, technical problem-solving, debugging, code evaluation, and cross-language implementation. The role spans both front-end and back-end systems, requiring you to understand and contribute to complete software applications. You will investigate unfamiliar codebases, build and validate solutions, and assess code for correctness, security, and maintainability. This is a fully remote contractor opportunity offering flexible working hours and approximately 15 hours of work per week. It is particularly suited to experienced engineers who enjoy solving complex technical challenges and can contribute independently.
You will contribute to a range of software engineering and AI training activities, developing, reviewing, and validating challenging technical tasks across the application stack. Your responsibilities will include:
Develop, modify, and debug front-end and back-end application components.
Build user-facing features alongside the services, APIs, and data models that support them.
Trace requests and data flows across browsers, front-end applications, APIs, backend services, databases, and external integrations.
Explore unfamiliar code repositories, understand existing architectures, and identify how different system components interact.
Diagnose and resolve technical issues involving application state, API contracts, authentication, data persistence, networking, and deployment.
Evaluate, improve, and validate code written in multiple programming languages.
Review AI-generated software solutions for correctness, completeness, performance, security, and maintainability.
Create, solve, review, and validate complex software engineering tasks, including translating complete coding implementations from one programming language to another.
Meet the project's minimum weekly task submission requirements and deliver work that complies with established specifications.
The ideal candidate is an experienced full-stack engineer with strong practical knowledge of production applications and the ability to work confidently across multiple technologies. You should be comfortable navigating unfamiliar systems, solving complex problems, and evaluating software quality. Required qualifications include:
Strong professional experience developing and maintaining production-ready full-stack applications.
Substantial hands-on experience in both front-end and back-end engineering.
Production experience working with multiple programming languages.
Strong understanding of browser-based applications, APIs, application state management, databases, and service integrations.
Experience understanding, evaluating, and contributing to the architecture of complete software systems.
Ability to navigate unfamiliar codebases and quickly understand existing application structures.
Excellent debugging, analytical thinking, and technical problem-solving skills.
Ability to assess code quality and identify issues related to functionality, performance, security, and maintainability.
Strong attention to detail and the ability to deliver accurate, well-validated technical work independently.
Availability to contribute approximately 15 hours per week, with the flexibility to choose working days and hours.
Competitive compensation: Attractive and competitive package, with payment based on completed tasks that meet project specifications.
Output-based earnings: Compensation reflects accepted task submissions rather than a fixed hourly rate. Completion time may vary depending on your experience and workflow.
Flexible schedule: Choose your working hours and days, including weekends, provided there is ongoing project activity.
Fully remote opportunity: Work from anywhere, with no fixed office location.
Part-time commitment: Approximately 15 hours per week, offering flexibility alongside other professional commitments.
Fast onboarding and start: The project typically fills positions within 48 hours, with selected candidates expected to begin their first tasks within 24–48 hours after completing onboarding.
Technical development: Work on challenging software engineering problems involving multiple programming languages, system architecture, debugging, and AI-generated code evaluation.