Harmonic
Harmonic · New York City (preferred) or US Remote · Full-time
Harmonic builds block production infrastructure at the core of Solana. We operate one of the leading Solana block builders, producing a meaningful share of mainnet blocks, along with the validator infrastructure underneath it, built on Firedancer. We are a small, senior engineering team whose systems sit directly in Solana's transaction flow.
This is not a middleware or dashboard role. We work close to the metal: networking, scheduling, memory layout, validator clients, and block production.
We are hiring a systems engineer to work on validator-level infrastructure, including deep work inside the Firedancer codebase.
This role is for someone drawn to performance-critical systems at the frontier, where the documentation has not been written yet because nobody has done it before. You will read and modify dense C code, reason about tile architectures and kernel-bypass networking, profile hot paths at the microsecond level, and help operate infrastructure that runs in production on mainnet.
The ideal candidate may come from HFT, low-latency trading, HPC, compilers, operating systems, databases, networking, distributed systems, or blockchain infrastructure. Direct blockchain experience is useful but not required. Years of experience matter less than slope: what we care about is taste, speed, ownership, and the ability to become dangerous in a complex codebase quickly.
Work directly on validator infrastructure, including Firedancer-adjacent and Firedancer-internal systems.
Read, understand, modify, and extend large C and Rust codebases with HPC->
Build and operate performance-critical validator, block-building, and transaction-flow infrastructure in production.
Profile and optimize across the full stack: networking, CPU scheduling, memory layout, NUMA, storage, consensus-adjacent paths, and application hot loops.
Investigate production incidents where the answer may involve kernel behavior, cache misses, packet drops, lock contention, or Solana runtime edge cases.
Turn ambiguous performance problems into shipped improvements.
Exceptional systems programming ability in C, C++, Rust, Zig, or similar. C matters most here.
Experience building or optimizing low-latency, high-throughput production systems.
Fluency with performance fundamentals: cache lines, branch prediction, syscalls, memory allocation, lock contention, queueing, CPU pinning, and tail latency.
Ability to navigate large, unfamiliar codebases and become productive quickly.
Strong ownership: you can take an underspecified production problem, investigate it, build the fix, ship it, and operate it.
You do not need years of blockchain experience, a crypto background, a specific degree, or years of seniority. Exceptional early-career engineers with the right fundamentals and hunger are encouraged to apply. We are happy to talk to engineers from HFT, infra, databases, kernels, compilers, trading systems, HPC, and networking.
Harmonic is small, technical, and fast-moving. Engineers own real systems, not tickets. High autonomy, high accountability, direct access to production, minimal process. Tasks here are rarely "implement feature X on this repo." They are ambiguous problems that need someone to independently diagnose, decide, and ship. We use AI tools daily and expect you to as well.
Location: New York City strongly preferred. We will consider fully remote candidates living in the United States who are exceptional fits.
Base salary range: $200,000 to $350,000, depending on experience and level.
In addition to base salary, all roles may be eligible for equity and performance-based upside. Base is only part of total compensation here, and compensation scales quickly with demonstrated impact. For exceptional candidates, we have the budget to be competitive with top trading firms; the posted range reflects base salary at hire, not the ceiling of what a career here looks like.
Benefits: Comprehensive benefits package including 100% employer-paid health, dental, and vision insurance; paid time off; a technology stipend; 401(k); and an annual discretionary bonus, which may include stock options.
Equal Opportunity Employer: We are committed to building an inclusive workplace where everyone has the opportunity to thrive. We provide equal employment opportunities to all applicants and employees without regard to race, color, creed, religion, sex, sexual orientation, gender identity or expression, pregnancy, national origin, age, disability, genetic information, marital status, caregiver status, citizenship or immigration status, veteran or military status, arrest or conviction record (where protected by law), or any other characteristic protected by applicable federal, New York State, or New York City law. We evaluate candidates on ability and evidence of work, and we welcome people with non-traditional backgrounds.
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