Senior Backend Engineer – Python & AI

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About the role

We are looking for a

Senior Backend Engineer to join an

AI Engineering team within a large international technology environment.

In this role, you will design, build, and operate robust

Python backend services that power

AI-enabled applications and reusable engineering capabilities across a complex enterprise ecosystem .

This is a highly hands-on senior individual contributor position, focused on solving real production challenges , making sound architectural decisions , and turning

AI and data-science capabilities into secure, reliable, scalable, and maintainable software.

You will take ownership of backend services from initial design through production operation , working closely with

Data Scientists, Product Managers, Platform Engineers, Security Specialists, and Architects .

If you enjoy building production-grade Python services , designing

APIs and distributed systems , working with

AWS , and integrating

AI/LLM capabilities into real-world applications, this could be a great fit.

What you’ll do

Design, build, and maintain scalable backend services and

APIs using

Python

Own backend services end-to-end, from architecture and implementation through deployment and production operation

Integrate

AI models ,

Large Language Models (LLMs) , and

Machine Learning services into production systems

Define service boundaries ,

data models ,

persistence strategies , and integration contracts

Design resilient distributed systems with appropriate failure handling ,

retries ,

fallbacks ,

rate limits , and asynchronous processing

Work with relational databases ,

data modelling ,

schema evolution , and persistence strategies

Deploy and operate backend services in

AWS cloud environments

Design services with reliability ,

security ,

observability ,

performance , and cost in mind

Handle production

AI concerns such as latency ,

structured outputs ,

sensitive data ,

model failures , and external API limitations

Improve automated testing ,

CI/CD pipelines ,

monitoring ,

dashboards ,

logging , and alerting

Work with

Docker and

Kubernetes to containerise and operate backend workloads

Lead technical discussions,



challenge weak architectural approaches , and help reduce unnecessary complexity

Participate in code reviews and help establish strong backend engineering standards

Mentor other engineers and share software engineering best practices

Collaborate closely with

Data Scientists, Product Managers, Platform Engineers, Security Specialists, and Architects

Must Have

Typically

7+ years of experience in

Backend Software Engineering , although technical depth ,

ownership , and impact are more important than an exact number of years

Strong

Python software engineering skills

Solid experience designing and building backend services and

REST APIs

Strong understanding of software architecture ,

service boundaries ,

distributed systems , and failure handling

Experience with relational databases ,

data modelling , and schema evolution

Hands-on experience deploying and operating production services in cloud environments , ideally

AWS

Strong knowledge of software testing and engineering best practices

Experience with

CI/CD pipelines and production deployment processes

Solid understanding of observability ,

logging ,

monitoring ,

dashboards , and alerting

Experience with

Docker and

Kubernetes

Practical understanding of security ,

privacy ,

sensitive data , and data protection principles

Strong problem-solving skills and ability to make and explain technical trade-offs

Experience working effectively across engineering, product, data, platform, and architecture teams

Fluent

English and

Spanish

Nice to Have

Experience with

FastAPI

Hands-on experience with

AWS services and cloud-native architectures

Experience with

Amazon EKS

Familiarity with

Infrastructure as Code , especially

Terraform

Experience with

PostgreSQL ,

Amazon Aurora , or similar relational databases

Experience with asynchronous processing and event-driven architectures

Familiarity with queues ,

messaging systems , or event-based integration patterns





Experience with enterprise identity ,

authentication , and authorisation

Experience integrating

AI ,

Machine Learning , or

LLM capabilities into production backend systems

Familiarity with production concerns around

LLM APIs , including latency ,

rate limits ,

retries ,

fallbacks ,

structured outputs , and observability

Experience in complex enterprise or large-scale digital environments

Hybrid model

– 2 days onsite per week in

Viladecans, Barcelona

Why join this project?

People first

– diverse and inclusive culture in an international environment.

Build production-grade backend systems that power real

AI-enabled applications

Work deeply with

Python ,

APIs ,

distributed systems ,

databases , and cloud-native technologies

Gain exposure to real-world

AI and LLM integration without moving away from hands-on software engineering

Work in an

AWS-based environment with modern cloud and platform engineering practices

Influence architecture ,

engineering standards ,

reliability ,

observability , and production quality

Take real ownership of services and technical decisions instead of simply implementing predefined tickets

Remain hands-on while having meaningful technical influence across the team

High team stability and collaborative culture.

€1200 per year training budget and continuous learning opportunities.

Adaptable compensation model .

Private health insurance and benefits package.

Flexible working hours and hybrid model .

Wellhub : fitness, wellness, and mental health support.

Football and paddle tennis teams sponsored by

Capitole .

Team buildings, global events, and strong tech communities .

Want to know more about us?

Click here and discover all the details.

Curious about our culture?

Check out what people are saying about us on

Glassdoor .

We know that not every candidate will meet 100% of the requirements. If your profile doesn’t match perfectly but you believe you can add value, we’d still love to hear from you.

Ready for the challenge? Apply now!

Empowering People, Unlocking Innovation.

Information Security Notice The employee will have access to confidential information related to Capitole and the assigned project. xugodme

Compliance with internal security and information protection policies is mandatory.

📌 Senior Python Backend Engineer (Barcelona)
🏢 Capitole
📍 Barcelona