Senior Backend Python Developer CDI Paris

Since 2015 papernest has been transforming the way people manage their contracts making subscription management and switching simple through one smart intuitive platform.

We have supported more than 2 million customers across France Spain and Italy. Along the way we have continued to invest in new verticals establishing papernest as a high-performing innovative and competitive scale-up in a fast-growing market.

With over 900 employees we are strengthening our position as a European market leader.

You will join the Telephony team owners of the platform that powers every inbound and outbound call across papernest call tracking routing scheduling real-time event processing and integrations with our telephony providers and Salesforce.

At papernest AI is core to how we build. We expect every engineer to be AI-powered. Youll be a role model for AI-augmented engineering: using AI tooling fluently across the whole development lifecycle while setting the standard for safe compliant and responsible AI usage on a business-critical system.

Main responsibilities:

This is a high-impact high-autonomy role; we are looking for a senior backend engineer to take the reins: own the architecture raise the technical bar and keep a system that handles business-critical call traffic reliable and fast.

Youll work mainly on our core telephony service an async FastAPI application following Domain-Driven Design progressively migrating a legacy codebase toward a clean well-specified architecture.

• Own the architecture and technical direction of the telephony backend and drive the ongoing migration from legacy code to our DDD architecture.

• Design and build reliable event-driven services: call tracking scheduling external event consumption and provider integrations (telephony providers Salesforce Pub/Sub).

• Write robust async Python (FastAPI SQLAlchemy) with strong typing full test coverage and clear specifications.

• Make and document the hard technical calls data modeling throttling retries failure handling pragmatically weighing trade-offs on a system where downtime means lost calls.

• Leverage AI tooling (Claude Code Cursor AI agents) to ship faster and better and define how the team adopts AI responsibly and within our usage and security guidelines.

• Set the engineering standard: code reviews mentoring and lifting the teams practices around testing observability and CI/CD.

• Collaborate closely with Product Ops and other engineering teams to turn business needs into solid technical solutions.

• Own your work end-to-end from design through autonomous deployment and monitoring in production.

About you:

• 8 years of backend software engineering with deep expertise in Python. Telephony real-time systems or CTI integration experience is a plus.

• Strong with our stack or close equivalents: FastAPI (or Django/Flask) async SQLAlchemy / PostgreSQL Redis message queues AWS.

• An AI-powered engineer you use AI coding assistants and agents fluently as part of your daily workflow and you know how to apply them responsibly and in compliance with usage security and data-handling rules. This is a top priority for us.

• Proven track record designing and operating business-critical production backend services at scale async event-driven integration-heavy systems where reliability is non-negotiable.

• Pragmatic by nature: you make sound trade-off-driven decisions ship the right thing rather than the perfect thing and know when to optimize and when to keep it simple.

• Solid grasp of software architecture (DDD a strong plus) clean code and rigorous testing you treat tests types and specs as part of the job not an afterthought.

• Experience mentoring engineers and raising team standards.

• Fluent in English working French is a plus.
  

What we offer:

Grow in an international and inclusive environment: Everyone has their place at papernest! With over 46 different nationalities its not unusual here to start your sentence in French and finish it in English or en español

Compensation: Youll receive a Business Creator Share Warrants (BSPCE) package upon joining according to the companys current policy.

Perks: As a home insurance provider and supplier of green electricity and gas we offer great deals to our employeesbecause our perks shouldnt be reserved just for our customers!

Health: We offer Alan a hassle-free and paperless health insurance provider with 50% coverage by papernest.

Meals: Enjoy a Swile card for your 9/day meal vouchers 50% funded by papernest. Plus theres breakfast every Tuesday at the office an Ideal Garden fridge on site and discounts at partner restaurants for healthy and balanced meals.

Sport: access toGYMLIBservice to enjoy discounted gym membership.

Training: Your development matters. Youll have access to continuous training tailored to your goalswhether theyre technical linguistic or managerial.

Career growth: Multiple paths are open to you to growby deepening your expertise or exploring new directions. Were here to support your professional ambitions.

Remote work: Benefit from 2 days of remote work per week to boost your focus and productivity.

Legal advice: Enjoy privileged access to Ekie for personalized legal and tax advice helping you handle all your administrative needs with peace of mind!

Hiring Process :

• First call with a Talent acquisition partner

• Interview with Julien Engineering manager

• Technical interview with a tech lead

• Last call with Raphaël CTO

If this is your challenge dont miss it! We look forward to meeting you no matter your gender race age religion disability or sexual orientation. Our selection processes and workplace are inclusive and adapted for everyone.

Ladies we strongly encourage you to apply! Even if you feel that you do not meet all the criteria mentioned in this offer please note that they are only indicative. Your application will be considered with great interest. Parity and diversity are assets for our teams!