Protocol Core Engineer

Char Network • Miami, FL

3d • Remote

About The Position

Core Protocol Engineer Position: Senior Engineer · Location: Miami, FL strongly preferred · Project: Char Network About Char Network Char Network is a proof-of-stake application coordination protocol built on Bitcoin. By anchoring data into Bitcoin through cryptographic proofs and economic guarantees, Char powers the next generation of Bitcoin layer twos. We’re a small, sharp, and adventurous team led by Bitcoin developer Jeremy Rubin , pushing the limits of what Bitcoin can be. Our work blends deep protocol expertise with a hacker’s creativity to unlock new capabilities for Bitcoin at scale. We keep things collaborative, fast-moving, and fun—where every contribution counts and every voice matters. Joining Char Network means working at the frontier of Bitcoin R&D and infrastructure, where the code you write and the algorithms you create will shape the future of the ecosystem. About the Role You’ll be building the systems that make Char Network run: consensus node implementation, Bitcoin transaction construction, proof generation and verification, and the testing infrastructure that keeps it all reliable. This is a hands-on engineering role where you’re writing the core software that anchors a proof-of-stake protocol into Bitcoin. You’ll work closely with our research team to translate new consensus and cryptography designs into hardened, production-grade code. You should be comfortable moving fast on early prototypes and then going deep on optimization and correctness.

Requirements

• Strong systems programming skills in C++ with a focus on correctness, performance, and memory safety
• Experience with low-level programming: memory management, concurrency primitives, performance profiling
• Comfort working across the stack including cryptographic primitives, networking, storage, and build systems
• Strong problem-solving instincts and the ability to debug complex, multi-layered systems
• Collaborative mindset; you give and receive code review feedback constructively

Nice To Haves

• Experience building Bitcoin applications or familiarity with Bitcoin Core codebase
• Practical experience with cryptographic implementations (hash functions, signature schemes, zero-knowledge proofs, BLS signatures)
• Familiarity with distributed consensus: ballot voting, leader election, fork-free protocols, Byzantine fault tolerance
• Experience designing and implementing P2P protocols for custom messages and state propagation
• Contributions to open-source projects in the Bitcoin or broader crypto ecosystem
• Understanding of timelock-based economic mechanisms and slashing conditions

Responsibilities

• Design and implement domain-specific consensus mechanisms: ballot advancement, leader election, and fork-free attestation coordination
• Engineer Bitcoin integration: stake bond design (taproot outputs, timelock slashing), cryptographic verification (BLS signatures, hash trees), and proof validation pipelines
• Build P2P networking and RPC/CLI interfaces for CHAR protocol operations: ballot propagation, leader advertisements, state inspection, and operator commands
• Design storage and indexing systems for protocol state: bond tracking, ballot history, and attestation persistence with reorg resilience
• Develop comprehensive testing infrastructure: multi-node simulation, edge case coverage, fuzzing, and DoS scenario validation; conduct rigorous code reviews across the entire stack

What This Job Offers

• Job Type: Full-time
• Career Level: Senior
• Education Level: No Education Listed