GenSoft

Gensoft is looking for a Senior Go Engineer for a long-term client project: a Go service that orchestrates cryptographic signing between distributed participants, including mobile clients. The service is already running in early production, and we need an engineer who can take ownership of it and bring it to a robust production baseline.

ABOUT THE PROJECT

- A Go-based service that orchestrates cryptographic signing between distributed participants, including mobile clients. It integrates with multi-party signing libraries, supports encrypted storage and must recover safely from interrupted sessions and other failures.
- The service works and is at an early production stage. There are open pull requests, observability improvements and concurrency issues to address. Handover from the previous team may be limited.
- You will work with backend and mobile engineers, QA and cryptography specialists. Collaboration across UK and North American working hours is important.
- Stack: Go, Linux, Docker, shared SDKs and bindings for mobile and web platforms.
- Initial focus: understand the codebase, resolve reliability and security issues, improve tests and support releases. Later work may include new product features and longer-term cryptography roadmap items.

RESPONSIBILITIES

Core service engineering
- Maintain and improve the Go service: signing orchestration, communication between participants, encrypted storage and failure recovery.
- Investigate concurrency, timeouts, interrupted sessions, network failures and service restarts; review open pull requests and fix race conditions.
- Improve logging and observability, assess the existing implementation critically and make careful, maintainable changes.
- Contribute to new features and future cryptography work as the roadmap develops.

Cryptography, SDKs and cross-platform integration
- Maintain integrations with multi-party / threshold signing libraries, working with cryptography specialists where changes affect protocol security.
- Contribute to shared SDKs and bindings connecting Go with mobile and web clients.
- Work with backend and mobile engineers to preserve API compatibility and consistent behaviour across releases.

Quality, testing and operations
- Improve automated tests for signing correctness, failure recovery and interoperability between server and mobile components.
- Support Linux and Docker deployments, dependency upgrades, monitoring, release processes and operational documentation.
- Investigate production issues and occasionally help with customer setup or logging problems.

Ownership and technical judgement
- Take primary ownership of a security-critical codebase and independently establish a robust production baseline.
- Assess technical risks and trade-offs, explain decisions clearly and make incremental changes with sound security judgement.
- Collaborate pragmatically with backend, mobile, QA and cryptography specialists across time zones.

REQUIREMENTS

- Strong hands-on production experience with Go: goroutines, channels, context cancellation, race detection, profiling and resource management.
- Experience owning production services, diagnosing complex failures and delivering well-tested fixes.
- Distributed systems knowledge: asynchronous messaging, retries, idempotency, state management and partial failures.
- Practical security engineering: authentication, encrypted storage, sensitive data handling and safe logging.
- Applied cryptography concepts: digital signatures, hashing, key management and signature verification.
- Automated testing, CI/CD, Linux, containers and production observability.
- Ability to understand an established codebase, make careful incremental changes and explain technical decisions clearly.
- English at Upper-Intermediate level or higher.

NICE TO HAVE

- SDK development for JavaScript/TypeScript or mobile platforms (Swift, Kotlin), including asynchronous APIs, packaging and Go interoperability.
- Cross-platform mobile development, secure storage or native modules.
- MPC or threshold signatures, distributed key generation (DKG).
- Blockchain transaction signing.
- Confidential computing and hardware-based attestation.
- Messaging protocols, Protocol Buffers, Prometheus or OpenTelemetry; interest in emerging signature schemes.

WHO WILL BE A GOOD FIT

- Experience with digital asset infrastructure or MPC is valuable, but the priority is strong production Go and sound security judgement.
- Relevant experience in other security-critical distributed systems also counts.
- You do not need experience with every "nice to have" technology. Evidence of ownership, careful delivery and learning across platform boundaries matters more.
- You are independent and can get up to speed on an existing repository with limited handover.
- You pay attention to correctness and take a careful approach to critical systems.
- You can assess implementation choices critically and explain risks and trade-offs clearly.
- You are pragmatic and collaborative with backend, mobile and cryptography specialists.
- You are comfortable diagnosing production failures and improving reliability through tested changes.
- You communicate effectively in a remote setup and are flexible to overlap with UK and North American working hours.

WHAT WE OFFER

- Fully remote work.
- Real ownership of the codebase and influence on technical decisions.
- Work alongside strong backend and mobile engineers, QA and cryptography specialists.

About the role

We’re looking for a Senior QA Engineer on a part-time basis for a long-term engagement with a US startup. The product is an iOS app that works together with a physical device and uses AI. The company is pre-launch.

You’ll be the only QA on the project. That means full ownership of quality: you decide what gets tested and how, you build the process from the ground up, and you work in close contact with the startup’s technical team.

This is not a role for executing someone else’s test cases. If you need an established process to slot into, this isn’t the position.

Schedule - please read carefully

The team is based in San Francisco, a 10-hour time difference. Because of that:

• Working hours shift into the evening - roughly until 9-10 PM Kyiv time

• Calls with the team two to three times per week at the start, one to two later on

• Everything else is async, you plan your own day

• Evening availability on agreed days is mandatory and not open for renegotiation after you start

If evening hours don’t work for you, it’s better not to spend time applying.

Requirements
 

Building processes from scratch

• Experience joining a project with no QA in place and building everything yourself

• Ability to set up a manual process from zero: critical flow map, test plan, regression suite, release checklist, bug workflow

• Ability to design an automation process from zero: choose the stack, lay out the framework architecture, wire tests into CI

• Ability to set testing priorities independently rather than waiting for tickets

Manual testing

• Deep experience testing mobile applications, with a focus on iOS

• Testing on physical devices, not only in the simulator

• Working with TestFlight, builds, and multiple iOS versions

• Verifying app permissions: microphone, Bluetooth, notifications, background behaviour

Automation

• 3+ years of commercial automation experience

• Experience automating native mobile apps, iOS preferred

• Proficiency with one of the following: Appium, WebdriverIO, XCUITest

• Ability to read and audit someone else’s test code, not just write from scratch

• Experience with CI/CD and how tests live inside a pipeline

AI testing

• Hands-on experience testing products with an LLM or ML underneath

• Understanding of how to verify non-deterministic output, where there is no single correct answer to assert against

• Experience with evaluation sets, scoring response quality, and catching regressions after a model or prompt change

• Familiarity with common failure modes: hallucinations, unstable responses, false refusals
 

API and backend

• Confident API testing with Postman or equivalent

• Ability to read logs and localise an issue to the device, the app, or the backend

• Working understanding of cloud services

Communication

• English at Advanced (C1) level or above — fluent spoken and written, no pauses to find words

• Comfortable holding technical discussions directly with a CTO

• Self-driven: nobody will hand you tasks every morning
 

Strong pluses

• Experience testing products where an app works together with a physical device

• Understanding of BLE: pairing, reconnection, behaviour on connection loss, data sync

• Experience with OTA firmware updates delivered through an app

• Working with audio as test data

• Experience at early-stage startups where processes don’t exist yet and have to be created

• Crash and feedback triage during beta, with Sentry or Crashlytics

• Understanding of privacy requirements: verifying data deletion and recording indicators

What you’ll be doing

• Regression testing ahead of weekly releases

• Feature testing before go-live

• Exploratory testing across device → cloud → app

• Building the QA process from scratch and growing it over time

• Auditing existing automated tests and gradually extending them

• Bug and crash triage during beta

What we offer

• Long-term engagement with the prospect of scaling up to full-time

• Real influence on the quality of a product that hasn’t launched yet

• Flexible schedule within the evening availability window

• Support from our team at every stage