Senior Experience Engineer (FTC)

The Experience team owns the human-facing side of Callsign: the client portal, our demo and client management platform (one platform for the whole client journey, from first demo through to proof of concept, onboarding, integration, analysis and ongoing management), the data-product UIs, and the design system and engineering standards behind all of it. This position is offered as a 12 month fixed-term contract with the successful candidate ideally joining in 2026. The candidate will already need to hold the right to work in the UK. What You'll Do Product & UX Own a product surface (portal domain, demo platform, SDK) and holds its product decision rightWithin the direction Product sets, decide what ships and how it worksTranslate a brief into an MVP and phases, define the success measures for what ships, and reshape or kill work that will not move them. Your surface carries a live measurement baseline (adoption, task success, performance) that decisions cite and post-release reviews are judged against; a decision that would change the direction goes to the PM, not around themPropose what to build next from your own product conviction, built from user and client contact, rather than merely executing requestsBe trusted to ship client-facing work without design review Frontend craft: Set the technical standard for the estate: your code is the reference. Lead the response to performance, accessibility or security findings, and anticipate them at design time Full-stack: Own services and their delivery machinery end-to-end (GitLab pipelines, charts, GitOps, infrastructure)Design API contracts consumers can live with long-termExecute cross-repo changes (decommissions, migrations) safely across team boundariesLead design review for your surface, where their design docs are the reference alongside your code Quality: Own testing strategy for a surface, including the release regression cycle: coordinate it, keep it honest, and drives flake to zero rather than tolerating it Platform: Own platform programmes (package-manager and framework migrations, test-framework transitions, runtime upgrades) end-to-end the planTranslate roadmaps into epics others can executeMentor junior team members Requirements Key Responsibilities Ship across the stack: TypeScript/React frontends, Node services (with some Java in the portal estate), API contracts, GitLab CI/CD, and deployment via Helm, GitOps and TerraformTreat the frontend craft triad - accessibility, performance, security - as engineering, with expectations that rise as you growBuild with AI as a core part of your workflow, with the verification discipline a regulated product demandsLearn the domain deliberately: fraud, identity, authentication, and our clients' operational world, because product decisions made without it are guessesWrite meaningful tests for everything you ship Required Skills & Experience A must: Solid JavaScript/TypeScript and ReactComfort somewhere beyond the frontend: an API, a service, or infrastructure. System design and architecture, designing features that span frontend, service and configuration. Evidence of AI-native working with stated verificationA testing instinct: you can design a test approach and defend itHas owned a product surface or platform programme including its worst weeksCan architect a frontend estate live (state, contracts, testing, deployment)Evidence of raising a team's standardsDemonstrable product judgement Nice to have: Java in production; design systems or component library work; SDK or library engineeringData visualisationExperience in regulated industries (fintech, identity, payments) Benefits Pension scheme with Scottish Widows Private medical cover with Vitality Life assurance (4x base salary) Personal Learning & Development Budget Cycle to Work Scheme Company Family Leave 25 days annual leave plus Callsign Bank Holiday Employee Volunteering Program