Senior Runtime Engineer

At Lightrun, we’re closing the gap between AI-generated code and real-world runtime behavior. Our platform restores the critical verification loop in enterprise environments by enabling safe, real-time observability - logs, metrics, and traces injected on demand into live systems - so engineers and AI agents can validate assumptions where code actually runs.Backed by Accel and Insight Partners, and trusted by leaders like Microsoft, Salesforce, Citi, and SAP, Lightrun is building the runtime foundation for the next era of agentic software development.

Join us to build cutting-edge systems, collaborate with world-class engineers, and shape how autonomous software is built in production.

Why this role matters

AI makes code generation easier, but proving that code works in production is still hard. This role focuses on closing that gap by building runtime technology that enables safe, real-time validation inside live applications, so engineers and AI agents can verify fixes, changes, and assumptions where they actually matter.

Responsibilities

• Build low-overhead runtime instrumentation and data capture in customer processes across Java, C++ and related environments
• Ensure compatibility across runtime versions, frameworks, and deployment environments such as containers, Kubernetes, Windows, and Linux
• Build backend services to securely define, distribute, and manage agent actions at scale
• Own agent-backend APIs and protocols, including versioning, compatibility, and release strategy across a large installed fleet
• Drive profiling and benchmarking to minimize runtime overhead and enforce
• performance budgets
  
  

• Strong C++ skills with production experience, especially in performance and memory safety
• Production experience with Java and/or .NET, particularly in core libraries, frameworks, or runtime-adjacent components
• Experience building high-performance systems under latency, CPU, and memory constraints
• Strong backend engineering experience designing and operating production services and APIs
  
  

• Hands-on experience with profilers and runtime instrumentation technologies, such as:
• Java: JVMTI, bytecode instrumentation, ASM, Byte Buddy, JIT/GC awareness, safe attachment patterns
• .NET: CLR Profiling APIs, ICorProfiler, IL rewriting, managed/unmanaged interop