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Goldman Sachs - Marcus UK
When you make the invisible visible, teams build better products
Launching a Customer-Centric Mobile App for Marcus UK
Case study - Product
2018-2020
How I used evidence, inclusive usability testing, and cross-functional alignment to shape the successful UK launch of the first Marcus mobile app
A story of risk mitigation, cross-market insight, and building world-class app–first experiences
MY ROLE
Executive Director / Principal User Researcher (embedded), Retail Bank
SHOWCASING
Mobile app · product research · usability testing · inclusive design · cross-market UX · onboarding optimisation · digital banking · cross-functional alignment
Why This Work Mattered
When leadership announced the UK launch of the Marcus US mobile app already in use, they assumed research wasn’t necessary; after all, it was just localisation. Change the currency symbols, update the date formats, and ship.
But the PM and I knew the risks were too high.
If Marcus UK was going to bring this mobile experience to market — especially with a high-profile launch — the product needed to work not just functionally, but emotionally and intuitively for UK customers.
Without evidence, Marcus UK risked confusing customers, creating support load, and damaging brand trust at a crucial stage of growth. UK mental models of banking differ from those in the US, and the existing app patterns hadn't been designed with UK users in mind.
Localisation is often equated to translating copy and complying with legal and regulatory requirements. This doesn't take into account how one market moves differently, uses banking tools differently, and brings different expectations of digital trust than in another market.
To successfully launch their US mobile app in the UK market, Marcus needed more than localisation. We needed to uncover how UK customers actually thought, behaved, and trusted.
The Before Picture
When I joined Marcus, Goldman Sachs’ newly launched online-only retail bank in the UK, the product was still young. There was no mobile app, only one savings product, and the entire customer experience lived on a browser-based website. And although the launch numbers were incredible, onboarding 250,000 customers in under eight months, the team had almost no understanding of why customers behaved the way they did.
Business functions (Product and Marketing) largely operated separately from Engineering and Customer Support, with design and research being seen as consultants to Product.
Analytics measured what happened, but couldn't show what customers needed. Onboarding had unexplained friction points. Support for older adults, a critical user segment for an upcoming Saga partnership, hadn't yet been evaluated.
When the UK team decided to launch the Marcus app, leadership initially believed research wasn’t needed as the US team had already tested it.
Challenges
Cultural challenges
Research was viewed as optional in product delivery; few had worked with a researcher before
Cross-functional siloes
Little visibility into customer behaviour beyond analytics or complaints
Organisational challenges
No research remit, so I had to create my own
Limited access to engineering rituals or back-office environments
No unified view of onboarding or customer pain points
Product challenges
Browsing and buying behaviours on the promotional page weren’t fully understood
Certain onboarding steps had hidden friction and unnecessary support load
App design patterns from the US didn’t align with UK expectations
Older adults’ needs were unknown ahead of the Saga partnership
Strategic risks
High-profile app launch with potential to erode trust if wrong
Lack of UK-specific testing on brand assets created for a US market
Regulated environment · inherited US designs · siloed teams · limited early influence · high launch pressure
The Turning Point
The turning point came early, during a period of relationship building. I realised the organisation didn’t just lack insight, it lacked user exposure. People couldn’t imagine the benefits of research because they had never seen real users struggle, succeed, hesitate, or express frustration.
So instead of asking for trust, I created opportunities for people to witness real users, building up the team's user exposure hours.
The mobile app project became the inflection point: the moment where research stopped being theoretical and became essential.
The fastest way to shift belief was to put cross-functional teams in the room with real users.
What I Did
1. Built foundational insight
Mapped the onboarding journey, analysed behavioural data, and embedded with customer support to understand real-world friction points.
2. Delivered quick unmoderated research wins
Captured how customers search for savings accounts and make decisions. Identified two different strategies and redesigned the promotional page to support both.
3. Ran inclusive usability testing ahead of the Saga partnership
Evaluated onboarding with older adults to understand trust, readability, device use, accessibility, and emotional reactions.
Identified missing trust markers, unclear instructions, and visual accessibility issues.
Prepared Customer Support with insight-driven scripts and expectations.
4. Created broad cross-functional participation
Cross-functional user exposure at an all-time high - in-person in the observation room during external studies were: Product, Design, Engineering, CS managers, Marketing, Product Strategy, Analytics, Legal, Tech Risk, Compliance, other researchers and senior leadership.
This became a turning point in research credibility and influence.
5. Ran high-impact usability study for mobile app ahead of launch
Secured budget by demonstrating product risks through early guerrilla research looking at UK-specific mental models related to mobile banking. Ran a two-day formal usability study with 12 participants, intentionally including an older adult segment.
Captured the “aha moment” that changed leadership’s mindset: A participant repeatedly entered their app passcode into the phone’s lock screen because the UI looked identical, proving a flawed design pattern that would frustrate all customers (not just UK). This led to immediate design changes in the UK and reinforced the US team’s global decision to remove the pattern.
The team fixed major issues for the UK before launch — including removing the problematic passcode step globally.
6. Turned insight into action
Produced highlight reels, facilitated “How might we” workshops, and partnered with engineering and product to prioritise changes, ensuring fixes were owned and shipped.
How things shifted
Marcus shifted from assumption-led to evidence-led product development. PMs brought research into early discovery, engineers became research allies, legal and compliance welcomed research insights to their decision-making, and UK insights influenced US product decisions for the first time.
Impact
Higher conversion from promotional page to onboarding
Much clearer content hierarchy and examples
Fewer failed ID checks due to clearer guidance
Reduced abandonment during ID verification through better messaging
Improved accessibility via clearer errors and form behaviours
Support options surfaced clearly in the app
“Move money” terminology aligned with UK mental models
Fixed onboarding gap when starting from the app
Critical app issues resolved pre-launch (including global passcode fix)
For Stakeholders
PMs involving research earlier
More inclusive patterns adopted by design
Engineering acting as research advocates
Legal and compliance incorporating customer insight into decision-making
Better support scripts and fewer avoidable calls
Stronger cross-functional alignment through shared observation
For the Firm
Research became expected in high-stakes product work
Insight included in leadership planning
First meaningful UK↔US research feedback loop
Evidence became a shared language across teams
Legacy
The research programme established new norms for evidence-led decision making, and left behind a more mature, customer-centred product organisation.
Marcus UK shipped a mobile app launch that avoided major usability pitfalls, aligned with UK customers’ expectations, and improved both web and onboarding experiences.
