Senior Product Designer
Jana Gonsenicova
I hand over working software, not a spec. From research to merged pull requests, I design and ship time-tracking software at Toggl.
I design for complexity users shouldn't have to see. The underneath still need to account for what can happen, and what happens next.
I map the rules before I draw the screen: what can happen, what happens next, and where those states collide. The interface comes after the logic.
I explore in , then converge and strip.
I don't explore in isolation. I bring developers in right during exploration and pull in PMs and customer-facing teams when their context can change the answer. When something is easier to understand in code, I build it there.
I don't hand off screens. I hand over a with the behaviour specified across states.
Not a Figma approximation — it runs in the production codebase and the team's own design system, with the loading, empty, error and edge states in place. I use AI tooling, MCPs and skills to work directly in the codebase; everything I open goes through the same review as anyone else's. Some of it merges directly; the rest engineers build from and cite in their own pull requests.
I trust over taste, including my own.
The method follows the question: production usage, surveys, interviews, usability testing, churn data. When the evidence disagrees with my solution, the solution changes.
This site is my own build.
this one too
The commits are real
Goals: designing a state system, not a feature
Case studyI prototyped the product, not just the screens.I took Goals from research to a working experience in code.Details about my role and the dated record of what I shippedEmailCopy to clipboardLinkedInOpen profileSwitch to Night modeMy detailed CVPDF or Word downloadGitHubExpand the detailed year of my prompt codingRead recommendations from my colleagues, clients and mentors

The timesheet kept getting more complicated. The interface didn't have to.
Case studyThe timesheet kept getting more complicated. The interface didn't have to.Product design · continuous ownershipThe pattern that outlived my involvement
Case studyThe pattern that outlived my involvementProduct design · originator, then advisor

From browsing to booking
Case studyFrom browsing to bookingWeb design · hospitalityExpand my language learning in DuolingoMore about meWho I am and how I got hereExpand my world map from Been, every country I have set foot inExpand my flight log from Flighty, every route I have flownToggl 2.0 on iOS and AndroidSole designer for the first versions of the brand new mobile appToggl 2.0 extension for Chrome and FirefoxSole designer for the first versions of the browser extensionWhat hiring managers ask me firstQuestions answered, and a search of the siteExpand the story of how this site got its lookPrague09:07
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