Senior Backend Engineer, Comms Core — Remote Spain

Affirm, Inc.; Madrid; Remote; EUR 86,000 - 122,000; Full time

Benefits offered by this job

Flexible Spending Wallets for tech,食?l

Away Days - wellness days to take off

Learning & Development programs

Parental benefits

Employee Resource & Community Groups

Job summary

Affim is seeking a Senior Software Engineer, Backend (Comms Core) to own and deliver backend capabilities for a high-volume communications platform. You will design multi-region, multi-tenant services, collaborate with cross-functional teams, and drive reliability, performance, and scalability across complex messaging workflows.

Based in Spain with remote-first flexibility, you will contribute to architectural decisions, integrations with external vendors, and on-call reliability while growing

Qualifications

• 5+ years of experience in software development or engineering, with a deep understanding of system design and architecture.
• Proficiency in modern programming languages such as Python, Kotlin, or similar.
• Track record of developing highly available distributed systems using AWS, MySQL, DynamoDB, and Kubernetes.
• Experience designing multi-region, multi-tenant platforms with strong isolation, scalability, failure recovery, and data-consistency guarantees.
• Experience integrating with third-party communications or messaging vendors and designing abstractions for capabilities, rate limits, and failure modes.
• Experience defining a technical plan for the delivery of a significant feature or system component with an elegant, simple and extensible design.
• Proficiency at making significant changes in a large code base with tools and practices for safe evolution.
• Proficiency with AI-assisted development tools and applying sound judgment to validate outputs.
• Ownership mentality, seeking feedback from team, manager, and stakeholders.
• Strong verbal and written communication for collaboration with a global engineering team.

Responsibilities

• Own and deliver quarterly technical goals for the Communications area.
• Design and evolve reliable backend services for high-volume communications across multi-region, multi-tenant environments.
• Collaborate with product management, design, analytics, security, and engineering partners through the product lifecycle.
• Design, implement, and operate resilient integrations with external messaging vendors.
• Identify and solve project, process, technology, or business issues affecting scalability and reliability.
• Define service-level objectives and metrics, improve alerting and incident response, and participate in on-call efforts.
• Improve design, testing, code review, rollout, and operational standards, advocating them through writing and talks.
• Mentor and develop team members, provide feedback and technical direction.
• On-Call Rotation - There would be an on-call rotation for this role as a requirement.
• Help develop talent and lead by example.

Skills

Python

Kotlin

System design

Distributed systems

Ownership

Tools

AWS

MySQL

DynamoDB

Kubernetes

Job description

Affim is seeking a Senior Software Engineer, Backend (Comms Core) to own and deliver backend capabilities for a high-volume communications platform. You will design multi-region, multi-tenant services, collaborate with cross-functional teams, and drive reliability, performance, and scalability across complex messaging workflows.

Based in Spain with remote-first flexibility, you will contribute to architectural decisions, integrations with external vendors, and on-call reliability while growing