Senior Fullstack Engineer
Siena AI · Remote · Argentina · Brazil · Poland · Finland · United Kingdom · Romania · Remote - Europe · Spain ·
COMPENSATION
€•• – ••k
Listed on the employer's job board (Ashby)
- Senior Fullstack Engineer
- Fully remote, global team
- Node.js + React + TypeScript
- LLM production experience required
- Async-first culture
Join Siena’s small, global team as a Senior Fullstack Engineer to shape the Agent of Record for CX. You will own meaningful parts of the platform, turning ambiguous problems into reliable systems for major consumer brands.
The team values direct communication, high standards, and low ego. You will work autonomously, making architectural decisions and shipping iterative releases without task-by-task management.
What you'll do
- Own features across frontend, backend, and infrastructure from definition to production
- Partner with product to define scope and ship high-impact iterative releases
- Make architectural decisions and document reasoning for team alignment
- Integrate language models into enterprise workflows with a focus on reliability
- Solve engineering challenges related to API performance and microservices scaling
- Maintain and improve AWS infrastructure with a DevOps mindset
- Mentor teammates through code reviews and knowledge sharing
What you'll need
- 5+ years of experience shipping and owning live production systems
- Strong proficiency in Node.js, React, TypeScript, and Express
- Proven experience shipping LLM-powered features to real users
- Ability to work autonomously without assigned tickets or constant supervision
- Experience building systems that real users depend on daily
Nice to have
- Experience with Next.js
- Knowledge of Infrastructure as Code tools like CDK or Terraform
- Proficiency in Python
- Familiarity with event-driven architecture
- Background in customer support or CX software
Stack
- Node.js
- React
- TypeScript
- Express
- AWS
- PostgreSQL
- Redis
- Next.js
- Python
How you'll work
- Fully distributed global team
- Async-first communication style
- Low bureaucracy environment
- Autonomous work structure
What you get
- Competitive salary plus equity or stock grants
- Learning budget for professional growth
- Premium AI tool accounts (ChatGPT, Claude, Perplexity Pro, Cursor)
- Quarterly budget for new AI tools
- Equal employment opportunities
Hiring process
- AI-assisted screening tools used initially
- All final hiring decisions made by humans
- Option to request a human-only review of application