Staff Backend Engineer

As a Staff Backend Engineer at THE VAULT, you design and ship the hardest components of an MPC-based crypto custody platform serving institutional and retail clients. This is a hands-on individual contributor role with real technical leadership-no people management-where you drive non-trivial initiatives through code, RFCs, and mentorship. You'll own critical systems including the policy engine, signing orchestration, key lifecycle workflows, and multi-tenant wallet services, shaping architecture in your area while working alongside cryptography research, security, and product teams.

What you'll do

• Design, write, and ship critical platform components: policy engine, signing orchestration, key lifecycle workflows, recovery flows, approvals, audit trails, multi-tenant wallet and account services.
• Lead non-trivial cross-cutting initiatives in your area through written RFCs, design reviews, and code, not through hierarchy.
• Build high-load, multi-tenant SaaS systems with tenant isolation, quotas, rate limits, backpressure, concurrency control, and predictable latency under spikes.
• Design for distributed systems and reliability: idempotency, retries, outbox/inbox, event-driven workflows, sagas and state machines, replay, and graceful degradation.
• Implement security-by-design practices: least privilege, secret handling, mTLS/JWT, tamper-evident logs, and audit-ready data models-designed for SOC 2, ISO 27001, and DORA scope from day one.
• Own performance and data work: profiling, load testing, benchmarking, contention analysis, GC tuning, strong relational modelling in Postgres or equivalent, migrations, indexing, and clear consistency boundaries.
• Develop AI-assisted code production as a core competency: ship production code with Claude Code, Cursor, and Codex; build prompt and agent patterns for your area; contribute to company AI engineering practices; judge when to use AI heavily (periphery, integrations, tests, docs) versus when to avoid it (cryptographic core, signing paths where blind generation is unsafe).
• Set patterns and shared libraries for services your area touches; raise the bar through code review and example.
• Own features end-to-end: design notes and RFCs, code, tests, observability, rollout, and on-call-no handoffs.
• Mentor senior engineers through your reviews and written designs.

What you bring

• Strong CS fundamentals as your primary strength. You reason from first principles about concurrency, distributed systems, consistency models, networking, and OS behaviour. You understand what locks and channels do and why, not just how to use them.
• Ownership mindset. You have owned non-trivial production systems end-to-end-design, ship, measure, improve, on-call. You don't wait to be told what to do, and you don't ship code you don't understand.
• 10+ years of backend engineering, including 3+ years at Staff level or equivalent senior individual contributor scope. Strong production experience in a modern systems language: Go, Rust, Java, C++, or comparable. Hands-on Go experience or genuine readiness to ramp on Go in the first month.
• Proven track record of Staff-level technical leadership through code, RFCs, and influence-without formal authority over teams. You can point to RFCs you wrote that the team adopted, initiatives you drove without being the manager, and patterns you set that outlasted you.
• Proven track record building high-load, multi-tenant SaaS in production with HA, incident response, and SLOs.
• Hands-on experience with modern backend stacks: gRPC/HTTP, queues/streams, caching, relational databases, Kafka/NATS or equivalent.
• Strong testing discipline: unit, integration, and contract tests; testability-first design; deterministic CI.
• Strong observability habits: structured logging, metrics, tracing, and end-to-end production debugging.
• Production-grade use of modern AI coding tools: Claude Code, Cursor, Codex, or comparable. You can point to what you have built with them. You read AI-generated code as a critical reviewer-you have instincts for what AI tends to get wrong, and you do not ship code you could not have written yourself.

Nice to have

• Exposure to custody, wallets, or signing systems: MPC, HSM, TEE, key management, approvals.
• Hardware wallet integration experience, such as Ledger.
• Multiple blockchain ecosystems: EVM and Bitcoin minimum; Cosmos, Solana, and others a plus.
• Custom agents, MCP integrations, or in-repo AI workflows that compounded a team's productivity.
• Designed and run evals for AI-generated code: correctness, security, style.
• Kubernetes and service mesh in production; SRE practices.
• Regulated-environment experience: fintech, security audits, compliance-driven engineering.
• Threat modelling and security review participation.
• Familiarity with SOC 2, ISO 27001, and DORA sufficient to design for them.

What we offer

• A Staff individual contributor role with real technical leadership, no people management, and no sprint mechanics overhead.
• An AI-forward engineering culture with budget and autonomy for tooling, models, and agents you need.
• Direct peers in cryptography research, security architecture, product, and delivery.
• Fully remote, any time zone with reasonable overlap to EU/CIS hours.
• Competitive compensation at Staff engineer level; equity participation; full benefits.

About THE VAULT

THE VAULT is an MPC-based crypto custody platform for institutional and retail clients, running threshold signing across HSM and Ledger hardware. The company is scaling toward Series A, launching its productized platform in 2026, and publishing original cryptographic research alongside the product.