Learnlight Platform

From 2021 to 2024 I worked as a full-stack JavaScript developer at Learnlight, a language learning platform serving 700,000+ learners across 180+ countries. The backend was built on Apollo Server with a GraphQL API, backed by PostgreSQL, MongoDB, and Memcached, running inside AWS.

The most impactful thing I worked on was fixing an N+1 query problem affecting a large number of endpoints. I noticed it myself — repeated database calls were flooding the terminal during development. I spent time properly understanding the problem before touching any code, working through documentation and talks on DataLoader until I was confident in the approach. The fix reduced queries from 36 to 1 on the worst-affected endpoints and cut resolver response times by up to 70%. I applied it selectively — where the N+1 count was low or the endpoint rarely visited, the overhead wasn't worth it.

I also owned the Oxford Learner's Dictionaries API integration end to end. The ticket was just to add the endpoint, but before touching the platform I built a standalone proof of concept to get familiar with the API's quirks — the definition field returns raw HTML inside JSON, which needed parsing with Cheerio before it was usable. Working through the edge cases in isolation first meant the production integration went in cleanly.

For SCORM, the platform was opening endpoints to external content providers and needed protection against excessive requests. I read through the available rate limiting options, built a PoC using graphql-rate-limit-directive to validate the approach against the existing stack, then implemented it in production.