Senior Backend Software Engineer - Python
Senior Python backend engineer in Aircall's Madrid office building the intelligence layer of an AI-driven Sales OS: designing production Python services and distributed systems, integrating SaaS tools, and building frameworks that orchestrate LLM-powered agents. Stack includes Python, FastAPI, Celery, PostgreSQL, Google Cloud, and Kubernetes.
- Compensation
- Not disclosed
- Location
- Madrid Office
- Work setup
- Not specified
- Seniority
- Senior
- Employment
- Not specified
- Experience
- 7+ years
- Category
- Backend
- Posted
Skills
Must have
- 7+ years of strong backend engineering experience
- Advanced Python expertise (async, typing, architecture patterns, testing)
- Experience designing scalable distributed systems
- Designs well-architected systems and writes clean, high-quality code with focus on performance and maintainability
- Experience with AWS
- Actively leverages AI coding assistants and AI-augmented engineering workflows
- Thrives in fast-paced startup environments with real ownership
- Strong communication skills for collaborating with Product, Design, and Business stakeholders
- Fluency in English
Nice to have
- Experience with GCP
- Spanish language skills
Full description
Aircall is a unicorn AI-powered communications platform transforming how teams win with customers.
For over a decade, we’ve believed voice builds the strongest business relationships. We bring voice, SMS, WhatsApp, and 250+ integrations together on one seamless workspace—so every customer conversation drives revenue, resolves issues faster, and builds trust. Our AI Voice Agents handle routine interactions while your team leads the conversations that matter most. Used by 24,000+ businesses worldwide.
We’re 600+ people from 40+ nationalities across Paris, London, Madrid, Berlin, New York, San Francisco, Seattle, Sydney, and Mexico City. We’re ambitious, product-driven, and execution-focused—built for visible impact, fast decisions, and real growth.
Come join us!
The Role
We’re looking for a strong Senior Python Engineer who’s eager to go beyond traditional backend development.
This role is for someone ambitious—someone who takes pride in building things well, but knows how to move fast in a startup environment. You strike the right balance between clean architecture and pragmatism, between perfection and progress.
You’re energized by hard technical problems—distributed systems, AI orchestration, architectural trade-offs, performance, and scalability. You can go deep when needed, but you’re equally focused on shipping, learning, and iterating quickly.
You’re curious by nature, committed to continuous improvement, and excited to bring the most effective modern approaches—whether agentic patterns or AI-augmented development workflows—into real-world production.
This isn’t just another engineering role. It’s an opportunity to help build the intelligence layer behind a next-generation autonomous Sales OS.
Key Responsibilities:
- Design and implement production-grade Python services with clean architecture and strong engineering discipline.
- Architect scalable, distributed systems using Domain-Driven Design (DDD) principles.
- Integrate with external SaaS systems (CRMs, dialers, meeting tools, OAuth providers).
- Optimize performance, latency, cost, and reliability of AI-driven systems.
- Build and orchestrate LLM-powered agents (planning, reasoning, tool usage, memory).
- Develop internal frameworks to manage:
- Agent coordination
- Tool execution
- Memory layers
- Event-driven workflows
- Work closely with AI engineers, product, and founders to transform complex sales workflows into autonomous processes.