Senior System Software Engineer

Sr Systems Engineer — Performance Measurement Engine

Paris (remote friendly in Europe)

We're hiring for a Paris-based devtool startup, seed funded with multiple funding rounds, currently a team of 5 engineers. Their open source product is already used by the engineering teams behind some of the most demanding projects in the OSS ecosystem.

Their core product: detect performance regressions on pull requests, before code hits production. The hard part is extracting reliable signal from noisy CI environments — virtualization, shared infrastructure, noisy neighbors. They've built serious techniques to solve this, and they're now looking for someone to push the measurement engine to the next level.

This is an early stage environment with high ownership. You won't be handed a ticket queue. You'll make architectural decisions, shape the culture, and work directly with the founders. If you need a stable roadmap and a large team around you, this is not the right place.

What you'll work on:

- High performance CPU simulation tooling

- Instrumentation of language runtimes (CPython, V8) to enhance measurement quality

- Kernel I/O emulation for hardware agnostic performance metrics

- Core architecture decisions with direct impact on the product

What we're looking for:

- Production experience in C, C++, Rust or Zig

- Deep understanding of Unix systems and kernels

- Open source contributions: we will look at your GitHub

- Genuine care about technical excellence, not just shipping features

This is not a role for someone who has used systems languages occasionally. We're looking for engineers who live in this space : the kind of person who has opinions about CPU architectures, has profiled real production code at the instruction level, and contributes to OSS because they want to, not because it looks good on a CV.

Nice to have:

- Knowledge of modern CPU architectures

- Experience with JS or Python runtime internals (V8, CPython optimization pipelines)

- GPU/CUDA experience with a solid understanding of CPU architecture

Stack: C/C++, Rust, Zig, Docker, Kubernetes, GitHub, AWS

Compensation: €70k–€100k+ depending on profile + equity

If your GitHub tells a story, we want to hear from you :)