Tania Papazafeiropoulou

Senior Mobile Engineer (Contract) · The Ready Collective

A platform for young athletes (R1). I work across the React Native app, the web app and the Node.js backend. Three-month contract, now continuing month to month.

• 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.
• Work on the Next.js web app and the Node.js backend.

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.
• Built the impact data dashboard for business partners end to end: impact cards such as households fed, a grid view and a downloadable PDF report.
• Redesigned the store confirmation flow on my own, end to end. Issue reports dropped by about 90%.
• Built Tomorrow's Collections for the partner platform, turning per-business availability rules into a simple view for operations teams.
• Shipped backend changes in the Rails API: collection claiming rules, event tracking, admin tools for store inductions and notification rules.
• Added Sentry error handling, CloudWatch dashboards and Mixpanel tracking to the partner and volunteer platforms.
• 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.

Senior Front-End Developer · Olio

• Promoted from mid-level to senior in about 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.
• Built the map view in the React Native app end to end: marker clustering, filters, a card carousel and current location. Fixed the app hanging by stopping markers re-rendering too often.
• 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.
• Added Datadog monitoring to the React volunteer platform.

Front-End & App Developer · Esquared Technologies

• Built features for an Angular 2 app, working directly with the founders and designers.

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.

Web Developer · IDG UK

• Built editorial and publishing tools for sites including PC Advisor, Macworld, ComputerWorld, Digital Arts Online and TechWorld.

Junior Software Developer · Kantar Worldpanel

• Built internal data tools and reporting automations.