Senior Software Engineer - Backend

Aircall•Town of Madrid, NY

About The Position

Aircall is an AI-powered customer communications platform used by over 22,000 companies worldwide to enhance revenue, accelerate issue resolution, and scale customer-facing teams. The platform integrates voice, SMS, WhatsApp, and AI into a seamless workspace, featuring an AI Voice Agent for routine calls, AI Assist for post-call tasks, and AI Assist Pro for real-time guidance. Headquartered in Paris with a strong North American presence in Seattle, Aircall also has teams in Madrid, London, Berlin, San Francisco, New York City, Sydney, and Mexico City. The company is ambitious, product-driven, and execution-focused, valuing ownership, continuous learning, and thoughtful speed. Within Aircall, a specialized New Product Unit is being launched to develop the future of autonomous sales. This unit focuses on improving the AI Orchestration Layer, which records and understands customer interactions across various channels (calls, video, email, WhatsApp) to autonomously execute sales workflows such as CRM updates, follow-ups, task creation, and coaching insights. The long-term vision is to evolve this into a self-improving, agentic Sales OS where specialized AI agents collaborate, coordinate, and continuously optimize the revenue process. This role is for a Senior Python Engineer within this New Product Unit, tasked with building the intelligence layer for a next-generation autonomous Sales OS. The ideal candidate is ambitious, skilled in balancing clean architecture with pragmatism, and energized by solving complex technical problems related to distributed systems, AI orchestration, architectural trade-offs, performance, and scalability. They should be curious, committed to continuous improvement, and excited to integrate modern approaches like agentic patterns and AI-augmented development workflows into production.

Requirements

7+ years of strong backend engineering experience.
Advanced Python expertise (async, typing, architecture patterns, testing).
Experience designing scalable distributed systems.
Ability to design thoughtful, well-architected systems and write clean, high-quality code, with a focus on performance and long-term maintainability.
Experience with GCP or AWS.
Energized by building systems that can reason and take actionâ€”not just generate responses.
Actively leverage AI coding assistants and are driven to push the boundaries of AI-augmented engineering.
Thrive in fast-paced startup environments where ownership is real and impact is immediate.
Strong communication skills are essentialâ€”youâ€™ll collaborate closely with Product, Design, and Business stakeholders, and stay deeply connected to our users and the problems theyâ€™re trying to solve.
Fluency in English is required.
Proficiency with Backend technologies: Python, FastAPI, Celery, PostgreSQL, uv (package-manager).
Familiarity with Frontend technologies: NextJS, Tailwind.
Experience with DevOps tools: Google Cloud, Kubernetes.

Nice To Haves

Spanish is a plus.
Experience with GCP (preferred).

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.
Use AI coding assistants effectively and experiment with AI-augmented development workflows.