Senior Fullstack Engineer — Remote, Flexible Hours, APIs & Frontend

X-FLOW; Warszawa; Hybrid; PLN 180,000 - 270,000; Full time

Benefits offered by this job

Competitive salary

Flexible hours

Career growth

Inclusive culture

Job summary

X-FLOW in Warsaw, Poland is seeking a Senior Fullstack Engineer to join our flagship Happy Color project. You will design and implement RESTful APIs with PHP/Laravel and build performant frontends using TypeScript and React, focusing on DX and scalable architectures.

You’ll work with PostgreSQL/MySQL, Redis, Kafka, and modern observability tools; participate in code reviews, testing, and deployment strategies, with flexible hours and hybrid work options.

Qualifications

• 4+ years of PHP experience with Laravel (DI, queues, profiling, REST, modularity).
• 4+ years of TypeScript with React/Redux Toolkit, routing, build processes, and bundle optimization.
• Database design with PostgreSQL/MySQL; Redis; indexes and transactions.
• Experience with Kafka and event-driven integrations.
• Security: OAuth2 and JWT.
• Knowledge of DDD, SOLID, 12-Factor App and observability tools.

Responsibilities

• Design and develop RESTful APIs using PHP/Laravel.
• Build frontend apps with TypeScript/React focused on DX and performance.
• Define and maintain API contracts and integrate with external services.
• Profile, optimize performance and reduce latency.
• Design database schemas, handle migrations and indexing.
• Write tests (unit/integration/e2e) and conduct code reviews.
• Ensure observability: logs, metrics, alerts, traces.

Skills

PHP Laravel

TypeScript React

PostgreSQL MySQL Redis

Kafka

OAuth2 JWT

DDD SOLID 12-Factor

Observability (Prometheus Grafana Open

Tools

GitLab CI

Jest

Playwright

JUnit/Codeception

Ant Design

Job description

X-FLOW in Warsaw, Poland is seeking a Senior Fullstack Engineer to join our flagship Happy Color project. You will design and implement RESTful APIs with PHP/Laravel and build performant frontends using TypeScript and React, focusing on DX and scalable architectures.

You’ll work with PostgreSQL/MySQL, Redis, Kafka, and modern observability tools; participate in code reviews, testing, and deployment strategies, with flexible hours and hybrid work options.