Backend Engineer

Kiwi Financial

10d • Remote

About The Position

We are looking for a Senior Backend Engineer with strong experience designing, building, and evolving scalable, reliable, and secure backend systems. This is a hands-on engineering role for someone who goes beyond feature implementation. We are looking for an engineer with strong technical judgment who can understand complex systems end-to-end, contribute to architectural decisions, identify and address technical debt, and continuously improve the quality and maintainability of our platform. AI is becoming a core part of how we build software. We expect engineers to effectively use modern AI-assisted development tools while maintaining strong ownership and engineering judgment over the code and systems they deliver.

Requirements

• 8+ years of professional backend engineering experience, with significant experience building and operating production systems.
• Strong hands-on experience with Node.js and TypeScript in production environments.
• Experience with Express.js or comparable backend frameworks.
• Experience with Python and familiarity with backend frameworks such as FastAPI, Django, or similar is highly valued.
• Strong knowledge of software architecture, design principles, and design patterns, including their trade-offs and appropriate use cases.
• Strong understanding of relational databases and PostgreSQL, including data modeling, transactions, indexing, query optimization, migrations, and performance.
• Experience working with ORMs and persistence patterns, understanding both their benefits and limitations.
• Strong understanding of API design, authentication, authorization, versioning, security, and third-party integrations.
• Experience designing systems for failure scenarios, including retries, duplicate events, partial failures, race conditions, and external-service degradation.
• Solid understanding of distributed systems and asynchronous processing.
• Experience with automated testing at different levels, including unit, integration, and end-to-end testing.
• Production experience with AWS or comparable cloud infrastructure.
• Experience with CI/CD, containers, and modern software delivery practices.
• Strong understanding of observability and production troubleshooting.
• Ability to analyze architectural alternatives, identify trade-offs, and clearly explain technical decisions.
• Strong ownership, problem-solving, and communication skills.
• Ability to work autonomously on complex technical problems while collaborating effectively with the broader team.

Nice To Haves

• Experience in fintech, payments, lending, banking, or other highly transactional environments.
• Experience building systems where financial correctness and data integrity are critical.
• Experience with event-driven architectures, queues, messaging systems, and asynchronous processing.
• Experience with AWS services such as Lambda, ECS/EKS, SQS, SNS, EventBridge, RDS, S3, and CloudWatch.
• Experience with Infrastructure as Code, such as Terraform or CloudFormation.
• Experience with high-volume transactional systems and distributed architectures.
• Experience implementing idempotency, outbox patterns, concurrency control, reconciliation processes, and fault-tolerant workflows.
• Experience with observability platforms such as Datadog, Sentry, or similar tools.
• Familiarity with DDD, Clean Architecture, Hexagonal Architecture, or similar architectural approaches — with the ability to understand when they are useful and when they add unnecessary complexity.
• Experience using modern AI coding assistants, agents, and AI-native development workflows.
• Familiarity with LLMs, tool calling, MCP, agentic workflows, or AI integrations is a plus, but AI specialization is not required.

Responsibilities

• Design, build, and evolve scalable backend services and APIs, primarily using Node.js, TypeScript, and Express.js.
• Own technical solutions end-to-end, from design and implementation through deployment, observability, and production support.
• Contribute to the evolution of our backend architecture and participate actively in architectural and technical design decisions.
• Identify, prioritize, and address technical debt, balancing long-term maintainability with product delivery.
• Apply solid software design principles and patterns, choosing appropriate solutions based on context and trade-offs rather than applying patterns by default.
• Design clear application boundaries and separation of concerns across services, business logic, and persistence layers.
• Design and optimize PostgreSQL schemas, queries, indexes, migrations, and transactional workflows.
• Build reliable financial workflows with appropriate strategies for idempotency, concurrency, consistency, retries, failure handling, and reconciliation.
• Design and maintain REST APIs and integrations with internal systems and external providers.
• Design asynchronous and event-driven workflows when appropriate.
• Build systems with strong principles around reliability, scalability, resilience, security, and performance.
• Work with AWS infrastructure and cloud services as part of developing and operating production systems.
• Improve production visibility through structured logging, metrics, tracing, monitoring, and alerting.
• Investigate complex production incidents, perform root-cause analysis, and implement sustainable solutions rather than temporary fixes.
• Maintain high engineering quality through automated testing, code reviews, documentation, and continuous refactoring.
• Use AI-assisted engineering tools to improve development speed, testing, debugging, code review, and engineering productivity while maintaining human ownership of technical decisions.
• Challenge existing technical decisions constructively and help continuously improve our engineering standards.
• Share knowledge and contribute to strengthening the technical capabilities of the engineering team.
• Collaborate closely with Product, QA, Data, Platform, and other engineers to translate business requirements into robust technical solutions.

Benefits

• The opportunity to work on critical financial products with direct impact on customers and business growth.
• High technical ownership and the opportunity to influence how our backend platform evolves.
• Meaningful architecture, scalability, reliability, and technical-debt challenges.
• An engineering environment where AI is becoming a core part of how we build software.
• A collaborative multidisciplinary team across Engineering, Product, Design, QA, Data, and Platform.
• 100% remote — Argentina or Colombia.

What This Job Offers

• Job Type: Full-time
• Career Level: Senior
• Education Level: No Education Listed