Senior Software Engineer, Custody (IC)

Strattmont • ,

7d • Remote

About The Position

The company is the digital-asset custody and infrastructure platform for the GCC. We hold institutional crypto safely, settle transactions across chains, and expose all of that as a developer API and a regulated-grade institutional console. You are a senior backend engineer with a custody and key-management background. You will be a foundational engineer on the company's custody platform, reporting to the Custody Platform Lead. You will ship production custody code across signing service, key management, chain integrations, and the transaction pipeline. You will own a chain or a subsystem. Within 3 months you should own a meaningful surface end-to-end (a chain integration, a signing-service component, a key-rotation flow). You will pair with the Custody Platform Lead and our in-house cryptography function on threshold signing, share generation, and key recovery flows. You will write post-mortems when things break. We treat these as architecture-improvement opportunities, not blame exercises. You will integrate new chains. Bitcoin, Ethereum and L2s, Solana, and an active onboarding queue. Engage in async written communication. Spec docs, PR descriptions, async design reviews.

Requirements

• 5-plus years of backend engineering, with the last 2-plus years on a custody platform or a key management system at a regulated entity. General fintech does not substitute.
• Hands-on with at least one of: HSM lifecycle (CloudHSM, YubiHSM, Ledger Vault, similar).
• Hands-on with at least one of: MPC / TSS (Fireblocks-style, Sepior, ZenGo, Curv-style).
• Hands-on with at least one of: Threshold signing schemes (GG18, GG20, FROST, CGGMP21, CMP).
• Production experience with one or more of: Bitcoin (UTXO model, PSBT).
• Production experience with one or more of: Ethereum (EIP-712, EIP-1559, account abstraction).
• Production experience with one or more of: At least one non-EVM Layer 1 (Solana, Sui, Cosmos SDK chain, similar).
• Reads Solidity, Move, or Rust well enough to integrate with new chains without hand-holding.
• Strong async written communication. Your PR threads, design docs, and intro reply are themselves a signal.
• English fluency.

Nice To Haves

• Experience with travel-rule / FATF compliance integrations (Notabene, Sumsub, TRP, IVMS101).
• Authored or contributed to an EIP, BIP, or chain RFC.
• Audit-contest finalist on Code4rena, Sherlock, or Cantina.
• Familiarity with regulated-financial controls: dual-control, four-eyes, M-of-N approvals, SOC 2 evidence collection.

Responsibilities

• Ship production custody code across signing service, key management, chain integrations, and the transaction pipeline.
• Own a chain or a subsystem. Within 3 months you should own a meaningful surface end-to-end (a chain integration, a signing-service component, a key-rotation flow).
• Pair with the Custody Platform Lead and our in-house cryptography function on threshold signing, share generation, and key recovery flows.
• Write post-mortems when things break. We treat these as architecture-improvement opportunities, not blame exercises.
• Integrate new chains. Bitcoin, Ethereum and L2s, Solana, and an active onboarding queue.
• Engage in async written communication. Spec docs, PR descriptions, async design reviews.

What This Job Offers

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