From assumptions to evidence:
product design grounded in user behavior.
I'm Stefanía Spangenberg, Senior Product Designer focused on understanding how users think — not how we assume they think. I work with a Lean UX approach: lightweight process, heavy on evidence. That means user testing early, iterating often, and making decisions based on what users actually do rather than what they say they want.
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Understanding users, not personas

I use Jobs to be Done, empathy mapping, contextual interviews, polls, and heatmaps to uncover what users are actually trying to accomplish. This goes beyond surface behavior — I'm after the mental models and motivations that drive decisions, which shapes every design choice downstream.

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Testing assumptions fast

I run usability tests early and often, before solutions are locked in. Low-fidelity prototypes, task-based testing, and rapid iteration cycles mean we validate direction before investing in execution — catching wrong turns when they're still cheap to fix.

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Translating research into decisions

I synthesize user insights into journey maps, prioritization frameworks, and clear design rationale that connects to product metrics. I also use A/B testing to validate specific design decisions with real usage data, turning qualitative understanding into measurable outcomes.

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Working in real teams, with real constraints

I work closely with engineers, PMs, and data teams — and I take technical constraints seriously, not as blockers but as design inputs. I can own a project end-to-end while staying aligned with the people who have to build and maintain what I design.

Case studies
B2B
WebApp
Lev Capital: Commercial Real Estate Financing
Brokers and borrowers were managing complex deals with no shared visibility, no structured workflow, and no way to track what was happening. I redesigned the core deal experience — document management, task coordination, lender analysis, and a real-time deal feed — reducing friction for both sides of the transaction.
See project
B2C
Mobile
PLG
Fennel: Invest in What You Believe
Fennel's app was live but losing users before they ever understood the product's value. I ran user interviews and usability testing, identified critical friction points across onboarding, ESG data clarity, and search — then led the design work to resolve them.
See project
B2B - B2D
Web
PLG
Forta: Crypto Security Network
Forta needed to introduce paid services to a developer-first community — three structurally different service types, each with its own configuration, payable in FORT tokens or USDC. I designed the purchase flow, user profile, and plan management system while navigating real technical constraints that shaped the MVP scope.
See project
B2B
Mobile
ShipHero: Warehouse Picking Flows
Warehouse workers were using a mobile app with inconsistent patterns across flows, no reliable error handling, and a steep learning curve. I identified three shared page structures across all picking flows and redesigned them as flexible templates — making the system consistent, learnable, and resilient to the errors workers face daily.
See project
B2C
Web
PLG
Restorando: Finding the Right Restaurant
Most users were leaving the restaurant profile page in under 3 seconds. Surveys revealed that nearly two-thirds weren't there to book — they were still deciding where to go. I reframed the experience around that actual job to be done, validated the redesign with usability testing, and confirmed it with an A/B test: 24% more conversions.
See project
B2B
Web & Mobile
Timeular: Meet Your Goals
Timeular users were tracking time but had no way to connect that data to goals. I mapped three structurally different goal types, ran prototype testing with real users, and used those insights to scope an MVP — launching the most common goal type first and building toward the full feature set iteratively.
See project
Other Designs at a Glance
warehouse fullfilment

ShipHero

Web App to provide easy fulfillment to small merchants.
See Payfully project

Payfully

Responsive Web App that provides capital and liquidity services to real estate agents.
See real estate lending app

Lev Capital Landing

Step by step wizard allowing users to request a quote for their property.
gastronomic mobile app

Restorando Android App

Restaurant Profile Redesign.
See Timeular New Business Model Project

Timeular Plans

The business model was changed and subscription plans were launched.
See Low Carbon Project

Carbon Emissions Landing

ShipHero launched a site to raise awareness about carbon emissions in shipping and how they could be significantly reduced by consumers.
See NestEasy Project

Nest Easy

Web application created by Payfully for property buyers to search brokers' properties.
See Kallpod Project

Kallpod

A mobile ordering platform designed specifically for restaurants and hospitality events, streamlining the customer experience and enhancing service efficiency.
See S+S project

S+S

A Facebook group emerged where women users of a female-centric planner interacted. The planner's founder requested a prototype for an MVP of an app that would facilitate better interaction, addressing needs and desires identified in conducted focus groups.
See Guardians Project

Safeguard Your Crypto Wallet:

This app introduced Guardians, a technology designed to safeguard crypto wallets at varying levels of protection.
See Linkeding Reviews See Linkedin Reviews