AI Solution Engineer - Full-stack / Rails Engineer (Barcelona)

Role Summary

• •Join a small, intense team of 5 engineers moving at startup speed with fast iteration cycles.
• •Develop and maintain a Ruby on Rails API backend with PostgreSQL, Redis, and Sidekiq, plus frontend work using Next.js and React.
• •Work on AI-driven customer support automation, processing millions of support tickets and e-commerce data daily.
• •Lead and build large Rails applications with a focus on product excellence and delivering user value.
• •Leverage recent experience with LLMs and AI integration, managing non-deterministic outputs in production.

About the Company

• •Yuma AI is a fast-growing scale-up with 30 employees across Paris, Barcelona, and Boston, founded in late 2022.
• •The company is a leader in AI support automation, serving 150+ merchants and automating up to 80% of customer tickets.
• •Founded by a 3-time YC founder, Yuma has achieved 10+ months of double-digit growth and 5x revenue growth in 2025.
• •Yuma values ownership, craftsmanship, and delivering value with a non-9-to-5, high-commitment culture.
• •The team embraces cross-functional work including product iterations, A/B testing, AI research, and performance optimization.

What You Should Know

• •Ideal candidates have deep Rails expertise and are pragmatic about balancing speed and quality.
• •Recent hands-on experience with large language models (LLMs) and AI is mandatory for this role.
• •Expect a fast-paced, high-expectation environment that requires 100% commitment and ownership.
• •The role offers exposure to cutting-edge AI tech in customer support automation and startup scale-up challenges.
• •Yuma welcomes raw talent and junior engineers aiming to grow into senior roles within 3 years.

Key Required Skills