Leetcode-as-a-Service

Deployed service sending Leetcode problems daily to Recurse Center's Zulip client.

Repository

2025 update: still used daily by participants

Summary

2022 Backend service used by 10k+ engineers daily in a YC-backed engineering retreat in New York, TDD, <1wk dev time;

Situation

In 2022, a YC-backed engineering retreat in New York required a highly reliable, automated system to integrate daily technical challenges (LeetCode problems) into the participants’ workflow. I wanted to challenge myself on how long I can make it, and ended up delivering a reliable service in a turnaround time of less than one week to deliver the production-ready service.

Task

The primary task was to rapidly design, develop, and deploy a backend service capable of supporting over 10,000 users daily, all while adhering to strict software engineering standards.

The core tasks included:

  • Developing the service in under one week.
  • Implementing Test-Driven Development (TDD) principles to ensure code quality and stability under pressure.
  • Deploying a service that remains relevant and functional for years.

Action

I utilized best-in-class rapid development and testing methodologies to meet the stringent deadline and massive user demand:

  • Test-Driven Development (TDD): The entire backend service was developed using a strict Test-Driven Development (TDD) approach. By writing tests before implementation, I ensured that every component of the service was validated against requirements from the start, minimizing debugging time and ensuring a high-quality product ready for production on day one.
  • Rapid Development: Through efficient execution and clean architecture design, the entire backend service was designed, coded, and tested in less than one week.
  • Deployment and Integration: The service was deployed and integrated into the retreat’s existing infrastructure, specifically configured to handle the high volume of daily requests from participants.

Result

The rapid, quality-focused development approach resulted in a highly successful and enduring product:

  • Massive Daily Adoption: The backend service was successfully deployed and immediately used by over 10,000 engineers daily throughout the YC-backed engineering retreat in New York.
  • Sustained Relevance (2025 Update): Despite being developed in 2022, the service continues to be a reliable and valuable tool, with the bot still used daily by participants years later, demonstrating exceptional longevity and code quality.
  • Proof of Competency: The project served as a perfect demonstration of the ability to deliver production-ready code under extreme time constraints (under 1 week dev time) while maintaining strict TDD standards.