Skip to content
Tsimafei Yefimenka
RUENPL
← All projects

Price comparison platform

Client work

One of the UK's largest comparison services for financial products

Role
Full-stack engineer, senior since 2024
Client
under NDA
Period
09.2022 — present, Godel Technologies Europe
Stack
React, Redux, Next.js, TypeScript, Monorepo, Node.js, Express, Jest, Playwright, Puppeteer, Docker, GitLab CI, GoCD, Claude Code, Windsurf, Codex

The problem

Several product sites live in one monorepo and share the same code. A change in a shared place lands in all of them at once, so it has to be checked wider than a single site. The other constant is page speed: search ranking and conversion depend on it.

About the project

Impartial comparison of financial products and services for the UK market: several product sites in one monorepo on React and Next.js, with a Node and Express layer between the front end and internal services. I have been on it since September 2022, first as an engineer, since April 2024 as a senior. Feature delivery, performance, tests and code review across the team.

How it works

aggregationBrowserNext.jsseveral productsBFFNode, ExpressQuote servicesInternal APIs

Outlined boxes are the parts I built

What I did

  • —Led the migration of a core client-facing module to React + TypeScript: 30% smaller bundle, Lighthouse performance up from 62 to 91.
  • —Raised unit and integration test coverage to 100%.
  • —Browser automation in production: end-to-end scenarios on Playwright and Puppeteer running across several product sites at once.
  • —Built screenshot capture on failure: when a test breaks in the pipeline, the shots of the state that mattered are taken during the run, so a failure is read from them instead of being reproduced by hand.
  • —Took part in a major refactoring onto a new framework: 25% better page performance with no loss of functionality.
  • —Cut critical production bugs by 40% through Jest/React Testing Library coverage and stricter code review.
  • —Migrated all services to GitLab with DevOps, and shipped a UI redesign across several products.
  • —Delivered two BFF/backend applications with spec-driven development, scaffolding from specs with Claude Code, Windsurf and Codex, 30–40% faster.