CV

Tania Papazafeiropoulou

Senior Front-End & Mobile Engineer & Tech Lead · United Kingdom / Greece · hello@tany4.com

I like working on products with real complexity and real users.

Developer for 13 years, most of them on React and React Native apps used by millions of people. I own systems end to end, work closely with product, design and backend, and care about performance and accessibility.

tania@tany4 ~ % cat strengths.txt
› shipping cross-platform apps
› front-end architecture that stays easy to change
› performance & accessibility
› working closely with product, design and backend
tania@tany4 ~ % open cv.pdf
tania@tany4 ~ %

Experience

05/2026 – Present

Senior Mobile Engineer (Contract) · The Ready Collective

Joined the R1 app in May 2026 on a three-month contract, now continuing month to month. Working alongside a former Olio colleague.

  • Built food logging for young athletes, with child-appropriate food ratings and an LLM step whose running cost is kept under control.
  • Designed how the team ships risky changes behind feature flags, turned on through code review.
  • Built the Mind and Energy progress logic and family sharing, so a child can be shared with a second parent and a coach.
  • Wrote the release smoke-test protocol the team runs before every release.
  • Contributing to the Next.js web app.
08/2023 – 03/2026

Front-End Tech Lead · Olio

A food-sharing app used by millions of people. I joined when there were fewer than 20 people and 3 developers, and worked there as it grew to over 100.

  • Set the front-end direction for the partner and volunteer platforms, weighing product needs against UX and long-term maintenance.
  • Led the rebuild of a 10-year-old scheduling system, migrated in small steps with feature flags and rollback. No disruption to users, and long-standing bugs gone.
  • Led internationalisation of the partner platform: locale-aware dates and times with Luxon, and Chinese as a new language.
  • Refactored, monitored and paid down tech debt to keep the apps fast, accessible and reliable.
  • Worked with product, design, operations and backend to turn complicated workflows into screens people could actually use.
  • Built hackathon prototypes, such as a partner platform and an AI-assisted appointment planner, to test ideas before committing to them.
  • Mentored engineers through pairing and code review, while still writing production code every day and helping unblock hard problems.
09/2018 – 08/2023

Senior Front-End Developer · Olio

  • Promoted from mid-level to senior within a year.
  • One of a small team that built Olio's React Native app from scratch and shipped the first version in 3 months.
  • Ran the App Store and Google Play releases, coordinating with product, QA and backend.
  • Led on app performance, spotting problems early and fixing them as they came up, for example on the item list and map views.
  • Led the move of the volunteer platform from Rails views to a React SPA, setting up routing, navigation and component patterns from scratch.
  • Then designed and built the flows that let charity volunteers use it alongside Olio volunteers.
08/2017 – 08/2018

Front-End & App Developer · Esquared Technologies

  • Built features for an Angular 2 app, working directly with the founders and designers.
03/2016 – 08/2017

Web Developer · Cult Beauty

  • Built UI features for a high-traffic e-commerce site. Worked on checkout and payment flows, integrating third-party payment methods including Klarna and PayPal. Contributed to both frontend and backend PHP code.
07/2014 – 02/2016

Web Developer · IDG UK

  • Built editorial and publishing tools for sites including PC Advisor, Macworld, ComputerWorld, Digital Arts Online and TechWorld.
01/2013 – 07/2014

Junior Software Developer · Kantar Worldpanel

  • Built internal data tools and reporting automations.