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SA
Posted 1y ago

Principal Java Engineer - JVM

Stack and Co
Dublin, Dublin, Ireland
€120k/yrOnsiteFull Time
Responsibilities
  • Building agent technology
  • Transforming running code
  • Optimising JVM performance
Requirements
  • 10+ years Java engineering
  • JVM internals
  • Bytecode
  • Low-level optimisations
  • Secure software focus
  • Debugging and performance tuning
Technical tools mentioned
JavaJVMBytecodeInstrumentationDebugging tools

Job description

Are you the kind of Senior Java Engineer who is an expert in the JVM and loves solving problems deep inside the runtime?

We’re looking for a seasoned technical heavyweight — a true master of the Java ecosystem — who lives and breathes bytecode, understands the guts of the JDK, and thrives on solving deep, complex problems in live systems. This is not your average Java dev role — this is a chance to get hands-on with the runtime itself and shape the architecture of high-impact cybersecurity products used across global enterprises.


What You'll Be Doing:

  • Building and evolving bleeding-edge Java Agent technology used in modern runtime application security.

  • Designing algorithms that dynamically transform running code to detect and neutralise threats in real-time.

  • Working in the guts of the JVM — manipulating bytecode, exploring obscure APIs, and optimising performance under extreme conditions.

  • Collaborating with elite engineers in a tight-knit R&D team where every line of code counts.

  • Contributing to product innovation and setting best practices across engineering, security, and DevOps.



Requirements

✅ What You Bring:

  • 10+ years of serious Java engineering experience — including JVM internals, JIT, garbage collection, and low-level optimisations.

  • Expert in low-level Java, Java Virtual Machine

  • Mastery of Java bytecode and classloading — you’ve probably written your own agents, class transformers, or custom instrumentation tools.

  • Passion for secure software development and an instinct for rooting out vulnerabilities before they happen.

  • Hands-on experience with complex debugging, performance tuning, and real-world system architecture.

  • Confident communicator who thrives in a collaborative, intellectually curious environment.


⚙️ Nice-To-Haves:

  • Familiarity with Groovy, Kotlin, Python, or TypeScript.

  • Background in building developer tools or security products.

  • Experience in mentoring or leading technical teams (or ambition to grow in that direction).



Benefits

If you are a strong very Senior Java Engineer up to Principal Engineer level or close it and you have the required Low-Level Java, JVM expertise, then please send your CV to Gerry Nolan at Stack and Co today via [email protected]