> Markdown version of [/jobs/ext/3594308-senior-experience-engineer-ftc](https://www.wearedevelopers.com/jobs/ext/3594308-senior-experience-engineer-ftc). Every page supports `.md` or `Accept: text/markdown`. Links point to the HTML versions so they work for humans too. Agent guide: [/agents.md](https://www.wearedevelopers.com/agents.md).

---

# Senior Experience Engineer (FTC)

- **Company:** Callsign
- **Location:** London, UK
- **Experience:** Expert
- **Salary:** £60,503.0
- **Contract:** Temporary contract
- **Skills:** Java (Programming Language), JavaScript (Programming Language), Application Programming Interfaces (APIs), Artificial Intelligence, Data Visualization, Node.Js, TypeScript, ReactJS, Gitlab, Gitlab-ci, Material UI, Front End Software Development, Terraform, Api Management
- **Published:** October 6, 2026
- **Apply:** https://www.adzuna.co.uk/jobs/details/5912667577

## About the Role

A must:

 * Solid JavaScript/TypeScript and React.
 * Comfort 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 verification.
 * A testing instinct: you can design a test approach and defend it.
 * Has owned a product surface or platform programme including its worst weeks
 * Can architect a frontend estate live (state, contracts, testing, deployment)
 * Evidence of raising a team's standards
 * Demonstrable product judgement

Nice to have:

 * Java in production; design systems or component library work; SDK or library engineering
 * Data visualisation
 * Experience in regulated industries (fintech, identity, payments).

## Description

* Own a product surface (portal domain, demo platform, SDK) and holds its product decision right
 * Within the direction Product sets, decide what ships and how it works.
 * Translate 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 them.
 * Propose what to build next from your own product conviction, built from user and client contact, rather than merely executing requests
 * Be 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-term
 * Execute cross-repo changes (decommissions, migrations) safely across team boundaries
 * Lead 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 plan
 * Translate roadmaps into epics others can execute
 * Mentor junior team members, * 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 Terraform.
 * Treat the frontend craft triad - accessibility, performance, security - as engineering, with expectations that rise as you grow.
 * Build with AI as a core part of your workflow, with the verification discipline a regulated product demands.
 * Learn the domain deliberately: fraud, identity, authentication, and our clients' operational world, because product decisions made without it are guesses.
 * Write meaningful tests for everything you ship.