Senior Fullstack Engineer (PHP/Typescript)

xflow; Warszawa; Hybrid; PLN 240,000 - 360,000; Full time

Benefits offered by this job

Flexible working hours

Remote/office options

Career growth opportunities

Job summary

X-FLOW, a mobile game company known for Happy Color, seeks a Senior Fullstack Engineer to advance its flagship project. You’ll build PHP/Laravel backends and TypeScript/React frontends, while shaping API contracts and deployment pipelines.

Join a diverse team with flexible hours and remote/office options, enabling impactful work on high-traffic apps and data-driven features.

Qualifications

• 4+ years of PHP with Laravel expertise including DI, queues and REST.
• 4+ years of TypeScript with React/Redux Toolkit, routing and build optimization.
• Database design with PostgreSQL/MySQL, Redis; experience with indexing and transactions.
• Experience with Kafka event-driven integrations and OAuth2/JWT security.
• Understanding of DDD, SOLID, 12-Factor App and observability concepts.

Responsibilities

• Design and develop RESTful APIs using PHP/Laravel.
• Build frontend applications with TypeScript/React focusing on DX and performance.
• Integrate with external services and define API contracts.
• Profile, optimize performance and reduce latency.
• Design DB schemas, migrations, indexing, and queries.
• Contribute to QA with tests, code reviews, and automated checks.
• Ensure observability with logs, metrics, alerts and traces.
• Participate in architectural design decisions.

Skills

PHP/Laravel

TypeScript/React

PostgreSQL/MySQL

Kafka

OAuth2/JWT

DDD/SOLID/OpenTelemetry

Tools

GitLab CI

Docker

Prometheus/Grafana

Job description

X-FLOW is a mobile game development company established in 2018. We gained recognition after the release of Happy Color, the most popular digital coloring book and one of the most successful ad-driven mobile apps in the world. We take pride in our diverse and talented team and partners, spread across the UK, Cyprus, the Netherlands, and other regions worldwide.

We are currently looking for a Senior Fullstack Engineer for our flagship project, Happy Color.

Key Responsibilities:

• Design and develop RESTful APIs using PHP/Laravel.
• Build frontend applications using TypeScript/React with a focus on performance and Developer Experience (DX).
• Integrate with external services; define and maintain API contracts.
• Optimize performance, perform profiling, and reduce latency.
• Design database schemas, handle migrations, indexing, and query optimization.
• Contribute to quality assurance: write tests (unit/integration/e2e), conduct code reviews, and automate checks.
• Ensure observability and reliability: implement logs, metrics, alerts, and traces.
• Participate in designing architectural solutions.

Requirements:

• 4+ years of experience with PHP, strong knowledge of Laravel (DI, queues, profiling, REST, modularity).
• 4+ years of experience with TypeScript, strong knowledge of React/Redux Toolkit, routing, build processes, and bundle optimization.
• Databases: PostgreSQL/MySQL, Redis; experience with schema design, indexes, and transactions.
• Message Queues/Buses: Kafka — experience with event-driven integrations.
• Security: OAuth2, JWT.
• Understanding of DDD, SOLID, 12-Factor App methodology, and observability (Prometheus/Grafana, OpenTelemetry).

Nice to have:

• Experience with Golang development.
• Development experience with Ant Design (Antd) 5+.
• Experience with or understanding of GitLab CI, feature flags, migrations, and blue-green/rolling deployment strategies.
• Testing tools: Jest, Playwright; for PHP — PHPUnit/Codeception; integration/e2e testing experience.

Technology Stack (Core):

• Backend:PHP (Laravel), REST, PostgreSQL/MySQL, Redis, Kafka, Clickhouse.
• Frontend:TypeScript, React, Redux Toolkit.
• DevOps:GitLab CI, Docker.
• Observability:Prometheus, Grafana, OpenTelemetry, Sentry.

What We Offer:

• Competitive salary and benefits package.
• Opportunity to work with a talented and passionate team in a creative and dynamic environment.
• Flexible working hours and remote/office work options.
• Career growth and professional development opportunities.
• A fun and inclusive company culture that celebrates diversity and creativity.

Join us and let’s create great product together!

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