Kotlin Full-Stack Developer

Senior Backend Engineer with Kotlin 

Onsights is a venture-backed AI startup bringing e-commerce–style analytics to brick-and-mortar retail and shopping centers. We build advanced location-intelligence solutions that help customers understand their visitors’ behavior. Where people go, what they do, and why. Our patented AI technology, developed by a world-class and globally distributed team, is gaining strong traction with large enterprise customers. We value collaboration, diversity, and continuous learning as we build innovative products together.

About the Role

Onsights is an AI startup bringing advanced e-commerce analytics to brick-and-mortar retail. We’re looking for a remote, full-time B2B Senior Backend Engineer with strong backend skills and B2-level English. You’ll help design, build, and scale our core systems, working closely with DevOps, frontend, and data science teams to deliver high-performance data collection and analytics platforms.

What You’ll Work On

• Backend APIs in Kotlin using Spring Framework

• Scalable services for data ingestion and processing

• SQL/NoSQL databases (performance & reliability)

• Integrations with internal and external systems

• Security, stability, and scalability of our platforms

• Code reviews and mentoring junior engineers

  
  

Tech Focus

• 75% Backend: Kotlin, Spring

• 25% Databases: SQL/NoSQL, optimization, performance

• Plus Python, Docker, Shell, AWS (EC2, S3, SQS, EventBridge)

Core qualifications

• 6+ years of software engineering experience, with at least 4 years focused on programming in Kotlin or Java

• Experience with the Spring framework, in particular Spring Boot

• Proficiency in Kotlin and SQL

• Hands-on experience with the development of backend services using the AWS ecosystem

• Experience with any messaging/data bus/queueing system (Kafka, RabbitMQ, SQS, EventBridge, etc.)

• Experience with modern coding tools like GitHub Copilot

• Proven ability to design and lead technical initiatives

• English at B2 level

  
  

Bonus qualifications - not required but relevant

• Expertise in media streaming technologies, services, protocols, and formats

• Experience with Dagster or other data orchestration/pipeline tool

• Experience developing solutions in/for the e-commerce or retail industries

• Experience working with 3D point cloud data

• Experience working at a SaaS startup

Recruitment Process (Smooth & Transparent)

1. Chat with Agata (Recruiter)

2. Talk with Joe (Leader of the Engineering Team)

3. Live coding with one of our engineers

4. Deep technical session with Kuba & Mikołaj

5. Final discussion with Michael (Senior Leader)

Total Rewards Package for Our Contractors

• Competitive compensation: $45 - $55/hr

• Flexible working hours and 100% remote work

• Team member referral bonus

• Opportunity to work with a team of creative, motivated, and fun team members!

• Innovative projects at the intersection of AI, data, and retail