Sr. Backend Engineer

Aplazo; Poland; On-site; PLN 211,595 - 338,552; Full time

Job summary

Aplazo is seeking a Senior Backend Engineer in Poland to drive the development of backend systems. You'll be responsible for independent feature ownership, delivering quality code, and mentoring engineers. The ideal candidate has at least 3 years of backend experience, strong Java skills, and fluency in Spanish. You will also work with AWS infrastructure and have the chance to contribute significantly to a growing fintech platform, fostering financial access and opportunity in Latin America.

Qualifications

• 3+ years building backend systems.
• Strong experience with Java, familiarity with Python/Go is a plus.
• Good understanding of distributed systems, APIs, and cloud infrastructure.
• Strong testing discipline including unit tests and integration tests.

Responsibilities

• Own features end-to-end, from design to deployment.
• Write quality, clean, testable code.
• Mentor newer engineers and assist with debugging.

Skills

Backend system development

Java (Python/Go a plus)

Distributed systems understanding

Testing discipline

Debugging skills

AI tool usage

Tools

AWS (ECS, Lambda)

PostgreSQL

Kafka

DataDog

Job description

About the Role

We're looking for a Senior Backend Engineer to independently own features and deliver high-quality backend systems. You'll take projects from spec to production, write code that others want to work with, and help mentor newer engineers.

At this level, you're a reliable, autonomous contributor—you can scope and ship features end-to-end with minimal guidance and proactively unblock yourself and others.

What You'll Do

• Own features end-to-end — Scope, design, build, test, and ship features independently

• Write quality code — Deliver clean, testable, well-documented code with strong testing discipline

• Unblock the team — Proactively help teammates debug issues and remove blockers

• Handle on-call — Confidently respond to incidents using observability tools

• Mentor newer engineers — Support E1s through pairing, onboarding, and code review

• Leverage AI daily — Use AI tools to accelerate coding, debugging, testing, and learning

• Pay down tech debt — Identify and fix issues that slow the team down

What We're Looking For

Technical

• 3+ years building backend systems

• Strong experience with Java (Python/Go a plus)

• Good understanding of distributed systems, APIs, and cloud infrastructure

• Strong testing discipline—unit tests, integration tests, edge cases

• Systematic debugging skills across service boundaries

AI Fluency

• Uses AI tools (Copilot, Claude, ChatGPT) daily for coding, debugging, and test generation

• Builds reusable prompts or workflows that help the team

• Teaches effective AI usage to junior engineers

• Curious about new AI capabilities relevant to backend development

Communication

• Writes clear design docs and runs small design discussions

• Gives and receives direct, timely feedback

• Fluent in Spanish; working knowledge of English for cross-team collaboration

Mindset

• Self-directed; you don't wait to be told what to do

• Comfortable with ambiguity and changing requirements

• Product-minded—you care about business outcomes, not just code

Nice to Have

• Experience in fintech, payments, or lending

• Familiarity with our stack: AWS (ECS, Lambda), PostgreSQL, Kafka, DataDog

• On-call and incident response experience

• Understanding of the Mexican fintech ecosystem (BNPL, credit, regulation)

Our Stack

Java (primary), Python, Go · AWS (ECS, Lambda) · PostgreSQL · Kafka · DataDog · Pulumi · Jenkins

Why Aplazo

Our mission is to empower financial access and opportunity across Latin America through fair, simple, and transparent solutions. Our tech vision: be the most beloved and innovative tech organization in Latin America.

We're a Series B fintech growing fast—you'll have real ownership, impact, and the chance to shape how millions of people access credit.

Personal data collected during the recruitment process will be processed in accordance with the Privacy Notice of Aplaz, S.A. de C.V. (“Aplazo”), available at our Privacy and Policy Notice.
Aplazo does not discriminate on the basis of race, religion, skin color, sex, gender, age, ethnic or national origin, marital status, disability, social or economic status, sexual preferences, or any other condition or characteristic. Selection is based solely on the qualifications and merits of the candidates.