Senior Product Designer

4-8 Full-Time About TestsigmaTestsigma is building the world's first Quality Intelligence Platform – the infrastructure layer between every code change and every confident release. The product is proven, the market is real, and the team is now scaling the platform that will define this category. The company operates at founding-team pace and holds a high bar across engineering, product, and GTM.
Role SummaryThis is a founding design seat. The Senior Product Designer owns the end-to-end product experience for a technically deep, AI-native SaaS platform. The role requires owning UX depth and UI quality simultaneously – journeys, flows, system, and activation – and working directly with the founding team, product managers, and engineers to close the gap between platform intelligence and customer experience.
Key ResponsibilitiesUX & Product Design

• Own end-to-end UX across all product surfaces – from discovery through daily use – across every user persona
• Lead journey mapping, information architecture, and friction identification before customers encounter issues
• Design PLG experiences: first-run onboarding, empty states, self-serve activation, and in-product growth loops
• Design AI-native interfaces: confidence states, partial results, uncertainty indicators, reasoning traces, and accept/reject feedback loops
• Produce high-fidelity Figma files with complete interaction states: hover, active, loading, empty, and error
• Build working prototypes in HTML/CSS, Framer, or ProtoPie for flows that must feel real to be evaluated

Research & Discovery

• Run user interviews independently and synthesize findings directly into design decisions
• Review session recordings, support tickets, and NPS responses and convert them into concrete UX hypotheses
• Maintain a documented UX-hypothesis backlog that drives continuous design prioritisation
• Track developer and QA tooling market direction and bring that intelligence into live design decisions

Design System & Production

• Own Design System v1: components, color, typography, patterns, and icons – fully documented for engineering use
• Close the design-to-production gap by reviewing in-progress builds and flagging drift from design intent
• Define and enforce an AI-assisted design workflow standard for the design function
• Participate in product definition discussions and defend UX positions with structural reasoning
• Defend design decisions to the founding team with documented rationale

Year 1 Deliverables

• Redesigned Copilot Generations review experience – measured improvement to accept-rate and time-to-first-accepted-test
• First-run onboarding flow that takes a new user to their first accepted test with no salesperson – before/after metrics defined and tracked
• Design System v1: shipped, documented, and adopted by engineering across all core surfaces
• Complete set of empty, loading, partial, and uncertainty states across the product – no raw dead-ends
• AI-native pattern library covering agent outputs: confidence, reasoning, Healer/Arbiter, coverage, and blast radius
• Continuous research cadence with a living UX-hypothesis backlog
• At least one in-product growth loop designed, shipped, and measured
• Documented design-to-production QA practice with a measurably smaller Figma-to-shipped gap at month 12
• AI-assisted design workflow standard adopted across the design function

Required Qualifications

• 5+ years designing complex B2B or developer-facing software products with dense information architecture and power-user workflows
• Strong UX methodology: research, journey mapping, IA design, and usability evaluation – must be clearly articulable and demonstrable
• Designed at least one PLG product end to end: self-serve onboarding, activation experiments, and growth loops
• High-fidelity visual execution: clean, well-structured Figma files with consistent components and complete engineering handoffs
• Prototyping beyond Figma – demonstrated experience in HTML/CSS, Framer, ProtoPie, or equivalent
• Proven independent operation: set design direction and defended decisions without a design director
• Peer-level collaboration with engineers and PMs – constructive pushback on technical constraints that are UX problems in disguise
• Tenure stability: fewer than two exits under 18 months in the last five years (exceptions require specific explanation)

Preferred Qualifications

• Experience designing developer tools, QA tools, or technical infrastructure products
• Designed AI-native interfaces at real scale: agent outputs, confidence states, non-deterministic result handling
• Built or significantly contributed to a design system with active engineering adoption
• Growth design background: activation funnels, in-product A/B experiment design, onboarding optimisation
• Comfortable with product analytics: Mixpanel, Amplitude, or equivalent – able to validate design decisions with funnel data
• Familiarity with motion design: transitions and micro-interactions that make a product feel responsive
• Experience with graph- or relationship-heavy data visualisations: dependency maps, traceability, blast-radius views
• Shipped a PLG onboarding flow with a measurable improvement to activation or time-to-value
• Defined an AI-tooling workflow standard for a design team

What This Role Is Not

• Not a visual-design-only role – screens that cannot be implemented or maintained are a failure, not a deliverable
• Not a role where research is a phase – research is a continuous input that feeds live design decisions
• Not a role for someone who needs design leadership to validate every decision – this role sets direction independently
• Not suited to candidates whose background is limited to marketing sites or consumer apps without workflow complexity
• Not a role where AI-native design means adding a chat interface to every surface
• Not a role for someone who waits for a complete spec before exploring – exploration is how specs get sharpened

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