Staff AI Backend Engineer [JavaKotlin] [EU-ONLY]

Madrid - Spain

Monthly Salary: Not Disclosed

Posted on: 4 hours ago

Vacancies: 1 Vacancy

Job Summary

About Kerno

Kerno is building the validation engine for AI-native backend development. As AI agents like Cursor and Claude Code become central to how developers write code the need for fast reliable validation grows with it. Kerno automatically generates runs and maintains validation tests (covering integration performance security and resiliency) directly in the IDE or CLI catching breaking changes and unintended side effects before code is merged.

Were a small remote and fast-moving team solving a hard problem at the intersection of developer tooling code analysis and AI.

The Role

Were looking for a Staff AI Backend Engineer to help shape the core of our product. Youll work across the stack from the validation and test generation agents to the backend platform and infrastructure. This is a high-impact role where your decisions directly affect the product our users rely on every day.

Tasks

What Youll Do

Design and build core components of Kernos validation engine code indexation test generation and execution
Work building AI agents that are in charge of test generation and code analysis
Build and improve the platform layer local and/or remote environment orchestration
Own features end-to-end: scoping design implementation testing and rollout
Collaborate closely with the founding team on technical direction and architecture
Help extend language and framework support as we grow beyond our current stack
Contribute to the reliability and performance of a system that developers depend on for fast feedback

Requirements

What Were Looking For

8 years of professional backend development experience with strong proficiency in Kotlin (or another JVM based language)
Experience designing and building distributed systems or complex backend services
Comfortable working with multiple languages we use whatever is the best tool for the right solution
Strong understanding of testing methodologies CI/CD pipelines and developer tooling
Experience with or strong interest in AI agents development
Familiarity with containerization and local environment orchestration (Docker etc.)
Experience working with databases
Ability to work autonomously in a remote environment and communicate clearly in writing
A product minded person you care about why youre building something not just how

Nice to Have

Experience building developer tools IDE extensions or CLI tooling
Experience with message brokers (Kafka RabbitMQ)
Familiarity with LLM APIs and prompt engineering in production contexts
Experience at an early-stage startup

Benefits

Why Kerno

Hard problems: Youll work on code analysis AI-powered test generation and real-time validation. This isnt a simple CRUD API.
High impact: Small team direct influence on product direction and architecture
Remote-first: Work from wherever you do your best work
Quarterly off-sites: Meet your colleagues in person once a quarter
AI-native: Were not adding AI as an afterthought. Its core to everything we build.
Growing market: AI assisted development is exploding. The need for validation tooling is growing with it.

About KernoKerno is building the validation engine for AI-native backend development. As AI agents like Cursor and Claude Code become central to how developers write code the need for fast reliable validation grows with it. Kerno automatically generates runs and maintains validation tests (covering ...