Senior Backend Engineer — Web App DevEx (Remote, Flexible Hours)

Runware; Spain; Remote; EUR 60,000 - 90,000; Full time

Benefits offered by this job

Paid time off

Stock options

Remote-first

Flexible hours

Family leave

Company retreats

Job summary

Runware is looking for a Senior Software Engineer to build and evolve the systems and APIs powering our Web App and Developer Experience. You will collaborate with backend, frontend, Product and Design to deliver developer-facing APIs and reliable internal services.

You will own backend work from requirements to delivery, ensure production systems are robust, and participate in architectural decisions. This role emphasizes autonomy, strong engineering practices, and contributing to high-impact

Qualifications

• Experience building backend systems and APIs.
• Proficiency in one or more backend languages and ability to learn quickly.
• Experience delivering production-grade, well-tested systems.
• Understanding of API design, asynchronous workloads and distributed systems.
• Strong fundamentals in security, reliability and performance.
• Excellent collaboration across engineering, Product and Design.

Responsibilities

• Build and maintain internal and developer-facing APIs and services powering the Web App and DevEx.
• Develop and evolve public API functionality including task types, validation, routing and WebSocket/REST behaviour.
• Own and maintain the Admin API and panel as an internal platform used across Runware.
• Work with usage, billing and customer data to ensure accuracy and reliability, including Stripe.
• Investigate and resolve production issues and security vulnerabilities affecting the Web App and its APIs.
• Write, test and review clean, maintainable code and contribute to strong engineering practices.
• Collaborate with Product, Design and engineering teams to clarify requirements and define technical solutions.
• Contribute to architectural decisions and work across frontend and backend boundaries.

Skills

Backend APIs

APIs design

Distributed systems

Security & reliability

Team collaboration

Tools

PHP

Symfony

WebSockets

Job description

Runware is looking for a Senior Software Engineer to build and evolve the systems and APIs powering our Web App and Developer Experience. You will collaborate with backend, frontend, Product and Design to deliver developer-facing APIs and reliable internal services.

You will own backend work from requirements to delivery, ensure production systems are robust, and participate in architectural decisions. This role emphasizes autonomy, strong engineering practices, and contributing to high-impact