Experienced JS Back-End Developer — Visual Challenge Solving Platform

We're looking for exceptional engineers with strong back-end fundamentals and proven experience building high-scale distributed systems to join us at Hola, where we offer a unique and widely used VPN service that serves millions of users around the world with a strong focus on privacy, performance, and innovation. In this role, you will solve hard engineering problems on a large-scale visual challenge solving platform that spans orchestration services, computer-vision inference, and cloud infrastructure. You will take full ownership of critical systems, from design to production, in a fast-paced and professional agile environment.



For more information about HolaVPN:

https://hola.org/

Responsibilities

• End-to-end design, development and ownership of critical back-end services, from architecture to production.
• Participate in system design and architecture planning, for optimal software performance, scalability and reliability.
• Solve complex engineering problems: distributed state, concurrency, tail latency, fault tolerance and high-throughput pipelines.
• Debug production issues end-to-end across services: gRPC channel churn, DNS/ASG failover, Redis queue backpressure, worker saturation and memory fragmentation.
• Design and maintain solver logic for complex visual challenges: image grids, drag-and-drop, object detection and browser automation.
• Build and optimize pipelines integrating OpenAI reasoning, computer-vision inference, Redis Streams, MongoDB session tracking and S3 screenshot archival.
• Take on independent responsibilities, while contributing to the team's collective goals.
• Actively learn, adapt and stay up-to-date with the evolving tech landscape, including best practices.

Requirements

• At least 3 years of hands-on experience in software development / engineering, with a strong focus on back-end systems.
• Strong engineering fundamentals: algorithms, data structures, concurrency, distributed systems and performance analysis.
• In-depth understanding of network protocols and security, including TCP/IP, DNS, HTTP, HTTPS, CORS, WebSockets and gRPC.
• Proficient in system design and architecture to ensure product functionality, performance, scalability, and reliability.
• Track record of debugging and fixing hard production issues across multiple services or languages.
• Fast learner, able to work independently and as a team player.
• Fluent in English, with excellent communication skills.

*Fully remote position for candidates who are not located in Israel.