Senior Software Engineer, Custody (IC)

Location: Riyadh Saudi Arabia. Remote-friendly globally. Optional relocation to Riyadh.
Reports to: Custody Platform Lead.
Type: Full-time.

About us:
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.

The role:
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.
- 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.

Must-haves:
- 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.

Hands-on with at least one of:
- HSM lifecycle (CloudHSM, YubiHSM, Ledger Vault, similar).
- MPC / TSS (Fireblocks-style, Sepior, ZenGo, Curv-style).
- Threshold signing schemes (GG18, GG20, FROST, CGGMP21, CMP).

Production experience with one or more of:
- Bitcoin (UTXO model, PSBT).
- Ethereum (EIP-712, EIP-1559, account abstraction).
- 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.

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.

This is not the right role if:
- Only frontend / dApp experience, no backend custody or key-management depth.
- "Crypto trader who codes." Algorithmic trading without custody experience.
- Anyone whose entire blockchain experience is a single hackathon, bootcamp, or DeFi side project.
- Currently subject to a non-compete blocking digital-asset custody for more than 6 months.

Stack:
- Backend: Go primary. Some Rust, some TypeScript. Aurora Postgres and ClickHouse. Temporal for orchestration.
- Cryptography: in-house MPC stack (TSS-based), HSM integrations, multi-chain signing service. Chains: Bitcoin, Ethereum and L2s, Solana, active onboarding queue.
- Infra: AWS, Kubernetes, GitHub Actions CI, Terraform.
- Security posture: SOC 2 Type II in motion, SAMA-aligned, intent toward ISO 27001 and dual-control workflows.

• Location: Riyadh, open to Remote Opportunity.

• Time-zone band: UTC-1 to UTC+5 for meaningful Saudi-hours overlap.

• Relocation (optional): if the candidate elects to relocate to Riyadh, we’ll support sponsorship.

• Tax / payroll: KSA payroll for relocators. Contractor or Employer-of-Record for remote-international.