FlexSolution

We're looking for a senior Go engineer to take the lead on a transaction-signing service for a Western company building secure infrastructure for digital assets.

The service is the "server-side participant" in a multi-party signing flow: it co-signs transactions together with users' mobile devices using MPC / threshold cryptography, so no single party ever holds a full private key. The core is already built and running — your job is to own it, harden it and take it to a solid production level, and later help ship new features such as transaction approval policies and post-quantum signatures.

This is a hands-on ownership role, not a ticket-taking one. You'll get real autonomy and work alongside backend and mobile engineers, QA and a dedicated cryptographer.

What you'll be working on 

• Owning the Go signing service end to end: coordination between signing parties, encrypted key-share storage, safe recovery after crashes, timeouts and dropped sessions 

• Hunting down concurrency issues and race conditions, reviewing open PRs and bringing the codebase to a stable, well-tested state • Improving logging, metrics and tracing so failures are easy to understand in production 

• Keeping integrations with MPC / threshold-signature libraries in good shape together with the cryptographer 

• Contributing to the shared SDKs that expose the Go core to iOS, Android and JS/TS clients, and keeping APIs backward-compatible 

• Building test coverage for signing correctness, failure scenarios and server ↔ mobile interoperability 

• Supporting Docker/Linux deployments, releases, dependency updates and the occasional production or customer investigation

What we expect 

• Several years of commercial Go in production — you're confident with goroutines, channels, context, the race detector, pprof and resource management 

• A track record of owning a live service: debugging hard failures and shipping fixes backed by tests 

• Solid grasp of distributed systems — async messaging, retries, idempotency, state handling, partial failures 

• Security mindset in practice: authentication, encryption at rest, handling secrets and sensitive data, logging without leaking it 

• Working knowledge of applied cryptography: digital signatures, hashing, key management, signature verification 

• Comfort with CI/CD, automated testing, containers and observability tooling 

• Ability to pick up an existing codebase quickly, make careful incremental changes and explain your reasoning 

• English good enough for daily technical discussions with an international team

Big plus 

• MPC, TSS or distributed key generation (DKG) 

• Blockchain transaction signing on any chain 

• Confidential computing / TEEs and remote attestation (AMD SEV-SNP especially) 

• gomobile or other Go ↔ Swift/Kotlin bindings; TypeScript SDKs; React Native / Expo 

• MQTT, Protobuf, Prometheus, OpenTelemetry 

• Interest in post-quantum signature schemes

Terms 

• Full-time, 100% remote, long-term contract (6+ months, likely extension) 

• Start ASAP 

• Core hours 10:00–17:00 UK time; possible occasional later calls

• Your own laptop is fine

When you apply, it helps a lot if you add 

• A few words about Go services you've owned in production and your personal role there 

• An example of a tricky production or security incident you investigated and how you verified the fix 

• Your GitHub or any public code, if available 

• Your rate expectations, availability for interviews and earliest start date