Senior Backend Software Engineer

Who you are

• You have built and operated production backend systems. You will spend your time working on and owning Go and Python services, databases, and APIs, and you know the difference between something that works on a laptop and something that holds up under production load, latency, and cost
• You can operate with a high degree of autonomy. You will be trusted to lead projects, make decisions, and drive outcomes. We work on open-ended problems with no established answer, and when the obvious approach fails you generate alternatives rather than stopping
• You do not trust a change until you have measured it. Reaching for the profiler, the trace, or the metric is instinct rather than afterthought
• You treat quality, security, and observability as engineering fundamentals rather than optional extras, and you make the case for addressing technical debt rather than living with it
• You raise the bar for the engineers around you in ways they would recognise: pairing on problems outside your own project, leaving reviews people learn from, and writing things down for the next person
• You want to work on things that matter. Our software sits underneath decisions taken by governments, defence organisations, and institutions operating where being wrong or late carries real consequences
• 4+ years of professional software engineering experience, with demonstrated ability to stand up production-grade services and experience owning features end to end
• Proficiency in building microservices using Go or Python
• Solid understanding of distributed systems, databases, and software engineering patterns
• Experience with cloud infrastructure and infrastructure as code, and with the CI/CD pipelines around them
• Strong communication and collaboration skills. Comfortable writing clear technical documentation and discussing requirements with colleagues from engineering and the wider team
• Breadth across the stack: improving deployment pipelines, understanding database behaviour, and a genuine interest in security engineering
• An interest in how the product is actually used, and a willingness to take analyst feedback into requirements discussions rather than treating requirements as someone else's problem
• Currently working with Go-based microservices
• Experience with Elasticsearch and PostgreSQL
• Experience with streaming or event-driven pipelines
• Experience with feature flags and trunk-based development. Features land close to weekly, and individual deploys go out several times a day across several projects
• Experience operating multi-tenant systems where data isolation is a hard requirement
• Experience working in software for defence, government, or other compliance-constrained environments

What the job involves

• We are looking for a Senior Software Engineer to join ExTrac's engineering team to help build and operate the services and pipelines the platform runs on
• ExTrac takes a continuously ingested, multi-source corpus and turns it into products analysts use to make decisions under time pressure
• You will be responsible for building and running the backend microservices that make that possible: services and databases that expose curated data through APIs, run search and aggregation over large indices, hold application state, and keep the whole thing fast and correct as volume and customer count grow
• The work is broad by design
• In a single quarter it spans API and service design, search and database performance, long-running data pipelines, cloud infrastructure, and the deployment tooling underneath all of it
• You will own services end to end across a Go and Python codebase, working alongside the AI team who build our analytical and agentic features, the frontend team who build the web and mobile interfaces, and the analysts and product managers who define what gets built
• Take an ambiguous problem, gather requirements, write a technical design, and ship to production with minimal oversight
• Own services end to end, including consolidating or decommissioning what they replace
• Contribute to and lead system design and architecture decisions
• Design APIs used by both internal teams and customers, and hold them to clear contracts and sensible versioning as the number of consumers grows
• Treat the storage layer as a design concern rather than an implementation detail: schema, indexing strategy, and access patterns. Establish clear access patterns and boundaries
• Develop Go and Python-based microservices to support data collection, processing, and querying
• Hold services to production standards for latency, cost, and reliability, with the instrumentation in place to know when they are not meeting them
• Build and operate high-throughput data streaming pipelines and work on improving scalability, robustness, and latency
• Optimise databases and index performance where it is the constraint on product behaviour
• Work directly with the analysts who use our products, turning what they hit in practice into changes in the system
• Iterate quickly against a live stream of product requests, flagging where they collide with longer-horizon platform work
• Partner with the AI and frontend teams to deliver cross-functional features, solving the engineering, performance, and reliability problems that sit outside of their scope
• Improve the shared foundations other engineers depend on: deployment pipelines, service templates, observability, and the environments their work runs in

The application process

• Initial Intro Interview with Hiring Manager - 30 Minutes
• Technical Assessment - 1 hour
• Competency-based Interview - 1 hour
• Founder Interview - 30 Minutes

Benefits

• Flexible working: work where you work best, with the opportunity to spend 2-5 days a week working with the team in our central London office
• An annual individual learning and development budget of £500
• A generous private healthcare package
• Cycle to work scheme
• 33 days of annual leave
• Sabbatical leave offer
• Enhanced pension contributions
• Enhanced parental leave
• Workplace nursery scheme
• Regular team lunches and socials
• An annual individual learning and development budget
• A generous private healthcare package
• On-target earnings (OTE) structure tied directly to customer outcomes
• A role that combines mission-driven purpose with cutting-edge technology in a fast-growing company.