Senior Full Stack Engineer

You’ll work across the full stack, building the software that UK police custody suites depend on every day. Our team owns features end-to-end, from database migration to UI and our stack includes:

• Frontend: React, TypeScript
• Backend: Java, Spring Boot
• Data: MySQL, GraphQL
• Infrastructure: AWS, Kubernetes, Argo CD, Terraform
• Observability: Datadog

We’re also genuinely investing in how AI changes the way we build software. We don’t just use Copilot for autocomplete. We’re building agentic workflows into our development process, using tools like Claude Code to automate routine work, accelerate code review, and let engineers focus on the problems that actually need human judgement. If you’re excited about shaping how a team works with AI, not just using it, this is the place.

If you were on the team last week, you might have:

• Designed and shipped a new workflow for custody officers processing detainees, from GraphQL schema through to React components

• Investigated a production issue using Datadog traces and logs, then pushed a fix the same day

• Paired with a teammate to untangle a tricky state management problem in a booking form

• Built an agentic workflow that reviews PRs, learns from human feedback, and posts weekly engineering highlights to Slack, all automatically

• Managed a cross-team feature end-to-end - designed the architecture, broke work into parallel workstreams, and coordinated junior engineers to deliver on time

• Reviewed a pull request, spotted a change that would unintentionally affect other parts of the app, and directed a safer approach in the comments

• Prototyped a new idea at one of the hackathons we run twice a year, a chance to experiment with new tech, explore wild ideas, and ship something fun with no constraints

What You’ll Need

You write clean, maintainable code and care about the impact of your work. We’re an AI-first team. AI tools are part of how we work every day - writing code, reviewing pull requests, investigating issues, and automating routine work. We expect you to be comfortable working alongside AI and keen to push what’s possible with it.

• Professional software engineering experience, including ownership of complex systems and delivery of large-scale technical initiatives

• Experience mentoring and supporting other engineers

• Strong technical judgement and the ability to make architectural decisions

• Experience leading projects across multiple teams or domains, influencing technical direction beyond your immediate area

• A strategic mindset, with the ability to balance immediate delivery with long-term technical health

• Experience with our stack: Java, JavaScript, TypeScript + React, and MySQL

• Experience with AI-assisted development tools like Claude Code and how they can improve your workflow

• A strong sense of ownership and accountability for both technical outcomes and team success

• Confidence operating in ambiguous environments and helping teams navigate technical trade-offs

• A collaborative mindset and strong communication skills

• Private medical, dental, and vision insurance through AXA Health and BUPA, fully paid for you and your dependents

• 18 weeks paid parental leave (gender-neutral, for both primary and secondary caregivers) plus a ramp-back programme

• Income protection (75% of salary) and death in service cover (4x salary), fully paid

• Pension through Nest with 3% employer contribution

• Gym reimbursement for you and your partner

• Equipment allowance to set up your home office

• AI tooling including Claude Code Enterprise, Microsoft Copilot, and ChatGPT Enterprise licences provided

• Spring Health membership with therapy sessions and mental wellness tools, fully covered

• Company performance-based bonus

• Paid sabbatical of one month at your five-year anniversary

• Biannual hackathons , learning budget, and a team that genuinely invests in your growth

What We Value

• Humility. You know the best ideas win, no matter where they come from. You ask questions before making assumptions and you’re as happy being wrong as being right, because either way, the team gets to a better answer.

• Inclusivity. You respect expertise in all its forms and actively seek out perspectives different from your own. You make space for others and assume good intent.

• Excellence. You care about quality in your code, your reviews, and how you communicate. You’re not satisfied with “it works” when it could be better, and you encourage the same standard in those around you.

• Diligence. You take ownership, mind the details, and understand that the software we build is used in moments that genuinely matter. You don’t cut corners when people are depending on the outcome., Applicants must be authorised to work in the UK. We are unable to sponsor or take over sponsorship of an employment visa at this time.

This role may require you to complete Non-Police Personnel Vetting (NPPV) security clearance up to level 3.

We feel passionately about equal pay for equal work, and transparency in compensation is one vehicle to achieve that. Total compensation for this role is market competitive, including a target base annual salary range of £90k-125k, plus bonus opportunity, company stock options, and a full benefits package. Please note that the higher end of this range will be reserved for candidates with appropriate experience who reside in high cost of labor markets.

Mark43 is approved to hire in Canada, the UK, and 36 U.S. states, including Alabama, Arizona, California (excluding San Francisco), Colorado, Connecticut, Washington D.C., Florida, Georgia, Iowa, Idaho, Illinois, Indiana, Kansas, Massachusetts, Maryland, Maine, Michigan, Minnesota, Missouri, North Carolina, Nebraska, New Hampshire, New Jersey, New Mexico, New York, Ohio, Oklahoma, Oregon, Pennsylvania, South Carolina, Tennessee, Texas, Utah, Virginia, Vermont, Washington, Wisconsin, and West Virginia. Before applying to a remote role, please ensure that you are able to perform the position in one of the states listed above. State locations and specifics are subject to change as our hiring requirements shift.

Applicants must be authorized to work for any employer in the country in which the role is being hired. We are unable to sponsor or take over sponsorship of an employment visa at this time.

Mark43 is a public safety technology company trusted by over 200 police forces worldwide. We build cloud-native software on AWS that police forces and emergency services rely on in their most critical moments, from managing custody records to dispatching officers in the field.

Our UK team of 25 is based in Central Manchester, helping British police forces replace outdated, fragmented systems with modern, resilient software. We’re part of a 400-person global company, but the UK team operates with startup energy: small enough that your work is visible, big enough that you’re backed by serious investment.