Nadia OseiProduct engineer

Curriculum vitae

Nadia Osei

Product engineer Lisbon, remote across CET

Open to staff-level roles from September

I build the parts of a product people actually touch: interfaces that stay fast under real data, design systems teams keep using, and the unglamorous plumbing that stops both from rotting. Ten years across health, fintech, and developer tools, most of it leading the frontend of one team at a time.

Right now
Staff product engineer at Kestrel Health
Focus
Frontend platform, design systems, accessibility
Previously
Orbital Bank, Hexlet Tools
Writing
osei.dev/notes

Experience

  1. 2023 – now

    Staff product engineer

    Kestrel Health Lisbon, remote

    Rebuilt the scheduling flow 340 clinics book through every day.

    • Took booking abandonment from 34% to 12% by rewriting the availability picker around real clinic data rather than an idealised calendar.
    • Led four engineers through a nine-month Ember to React migration of 180,000 lines with no feature freeze and no rollback.
    • Put performance budgets in CI, so regressions fail the build instead of arriving in a quarterly report.
    • Wrote the accessibility standard the product org now audits against.

  2. 2020 – 2023

    Senior frontend engineer

    Orbital Bank Berlin

    Built the design system eleven product teams still ship on.

    • Shipped 64 components with visual regression tests, adopted by 11 teams inside a year.
    • Owned the card-issuing dashboard end to end, from the Figma review to the on-call rota.
    • Cut first contentful paint from 4.1s to 1.2s on a throttled 3G connection.

  3. 2018 – 2020

    Frontend engineer

    Hexlet Tools Berlin

    Documentation and plugin marketplace for a developer CLI.

    • Rebuilt the docs site around search-first navigation; monthly reads grew to 1.9 million.
    • Shipped the editor plugin marketplace, including the review queue the team still uses.

  4. 2016 – 2018

    Developer

    Studio Fennec London

    Agency work: twenty-odd client sites, one of everything.

Selected work

  • Ledger

    Open source / maintained since 2021

    A spreadsheet that reads its formulas as code. 8,200 stars, 61 contributors.

  • Quiet Hours

    Side project / macOS and web

    A focus timer with no streaks, badges, or notifications. 40,000 people use it.

  • Specimen

    Contract / type foundry

    A specimen builder for variable fonts, now the foundry's whole storefront.

Education

  1. 2012 – 2015

    BSc Computer Science

    University of Manchester First class

Speaking & writing

  1. 2025

    Performance budgets that survive a roadmap

    Front Conference Zurich

  2. 2024

    Migrating a legacy frontend without a freeze

    Smashing Magazine Essay

  3. 2023

    Accessible date pickers, the whole problem

    osei.dev Essay

References on request Last updated July 2026