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 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 features end-to-end, from ambiguous requirements to shipped experience: fills design gaps with defensible decisions and delivers a coherent flow rather than a set of components
- Contribute actively in refinement: challenge requirements with evidence, propose simpler alternatives, and bring product ideas of your own
- Know the outcome each feature serves, instruments what they ship so that outcome is measurable, and checks whether it landed (usage, feedback, demo performance) rather than stopping at merge
- Understand the domain the product lives in (fraud, identity, authentication, and the client's operational world) well enough so that gap-filling decisions reflect
Frontend craft:
- Implement non-trivial components and async data flows
- Diagnose and fix performance and accessibility issues rather than merely detecting them
- Handle secrets/config surfaces safely
Full-stack
- Ship features that span frontend, backend service and configuration
- Debug across the boundary to root cause
- Significant changes start as a written design others can review, rather than as code
Quality
- Design the test approach for your features (what gets unit, component and e2e coverage, and why)
- Keep regression suites healthy in your area; e2e failures you own get fixed rather than retried
Platform:
- Land toolchain and pipeline improvements (build config, CI automation, test infra, dependency upgrades) beyond your immediate feature work.
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 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.
Required Skills & Experience
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.
Would be great:
- Product judgement demonstrable from your history: UX decisions made and defended without a design spec.
- Ownership of a surface or programme through its worst weeks, at any scale.
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).
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
Skills Required
- Right to work in the UK
- Solid JavaScript or TypeScript experience
- React experience
- Experience beyond frontend development, such as APIs, services, or infrastructure
- System design and architecture experience spanning frontend, services, and configuration
- Evidence of AI-native working with verification discipline
- Ability to design and defend an appropriate testing approach
- Product judgment demonstrated through UX decisions made without a design specification
- Ownership of a product surface or program through difficult periods
- Production Java experience
- Design systems or component library experience
- SDK or library engineering experience
- Data visualization experience
- Experience in regulated industries such as fintech, identity, or payments
What We Do
Callsign is pioneering digital trust through proprietary technology that uniquely mimics the way humans identify each other in the real world. Positive identification of genuine users delivers privacy, safety and minimal friction whilst ensuring that bad actors are blocked. Through a simple Swipe or Type, users can be personally recognized to a 99.999% accuracy, delivering the highest fidelity AI based user recognition for the digital world.
