Senior Full Stack Developer

About the job
The Senior Full Stack Engineer builds and ships AI product features end to end, from LLM workflows on the backend to intuitive interfaces on the frontend. The role is key to making Sintra's AI helpers reliable, scalable and easy to use. It's a new position in the Engineering department and suits someone who can deliver on their own in a fast-moving team.
Job description
• Build and maintain AI product features across frontend and backend using TypeScript, Node.js and React.
• Develop reliable LLM workflows, including tool calling, prompt engineering, error handling and fallback logic.
• Create user-friendly frontend interfaces for complex AI functionality in collaboration with designers.
• Implement logging, monitoring and clean architecture to ensure system reliability and scalability.
• Contribute to code reviews, technical discussions and team collaboration while independently delivering features.

3+ years of back-end experience with TypeScript and Node.js (NestJS or Next.js).
Experience in front-end development with React.
Knowledge of SaaS business models.
Experience working in a fast-paced environment.
Proficiency in English.
Nice to have:
Experience with LLM integrations, including tool calling, function definitions and prompt engineering.
Experience implementing payment and subscription systems in web applications.

Equity package: a share in the company’s long-term success.
Flexible working model that supports a healthy work–life balance.
Private health insurance.
Workout sessions with a personal trainer.
Free lunch in the office every workday.