Staff Software Engineer — AI-Native Features (Rails/React)

Factorial; Madrid; Hybrid; EUR 90,000 - 130,000; Full time

Benefits offered by this job

High growth environment

Competitive ESOP plan

Private health insurance

Wellbeing and fitness programs

Office snacks & fruit

Job summary

Factorial is seeking a Staff Software Engineer to build AI-native features using Rails and React. You’ll lead technical initiatives, work closely with Product and Design, and ship real features in production.

You’ll design scalable systems, run AI-enabled product experiences, and ensure reliability and compliance across teams. You’ll influence architecture, own end-to-end delivery, and push for reusable components while mentoring others.

Qualifications

• Experience shipping production software with strong backend and frontend skills.
• Proven ability to ship features using Rails and React in production.
• Experience integrating LLM APIs into product features and shipping to users.
• Excellent API, cloud platform, and system design knowledge.
• Ability to lead technically and align with Product and Design teams.
• Clear English communication; Spanish is a plus.

Responsibilities

• Lead technical initiatives and set direction for roadmap chunks.
• Collaborate closely with Product and Design from early conversations.
• Own end-to-end systems from problem discussion to production maintenance.
• Engage with customers to inform technical decisions.
• Define AI feature design, scale, reliability, and governance.
• Promote spec-driven development and reusable components.

Skills

Backend & Frontend

Rails

React

LLM APIs

API design

Cloud platforms

Leadership

English communication

Tools

Rails

React

Job description

Factorial is seeking a Staff Software Engineer to build AI-native features using Rails and React. You’ll lead technical initiatives, work closely with Product and Design, and ship real features in production.

You’ll design scalable systems, run AI-enabled product experiences, and ensure reliability and compliance across teams. You’ll influence architecture, own end-to-end delivery, and push for reusable components while mentoring others.