Skip to main content
Nikolai Kondratev Nikolai Kondratev

Work

Selected work from the last six years. Each item says what I built and at what scale.

  • Google Workspace calendar sync engine

    HeYou (2026 to present), sole engineer

    • TypeScript
    • Bun
    • Hono
    • PostgreSQL
    • Google Workspace

    Status: In production.

    Whole-organisation calendar sync for a sales-intelligence platform, using Google Workspace domain-wide delegation.

    • An incremental sync engine handling 16 edge cases in the Google Calendar API, each found by measuring live behaviour.
    • 12 database tables covering calendars, events, attendees and sync state.
    • Private event data filtered at ingest rather than on read. The design stores about 62% less than the read-time alternative.

  • Company-hosted CDN on .NET 10

    Independent contract, Belgian software company (2025 to present), sole author

    • C#
    • .NET 10
    • Testcontainers
    • SkiaSharp

    Started as a per-block image bug in one client’s site and became a shared platform service.

    • URL-to-hashed-storage indirection with streamed reads.
    • Signed URLs with constant-time signature comparison.
    • Image resizing on a bounded-channel queue, using SkiaSharp.
    • An idempotent two-way migration tool for moving existing assets in and out.
    • An SDK dual-targeted so both .NET 10 and legacy .NET Framework 4.6.1 applications can consume it.
    • 320 test methods running against real dependencies with Testcontainers. Claude Code assisted.

  • Production database performance and funnel metrics

    HeYou (2026 to present)

    • PostgreSQL
    • TypeScript
    • Bun

    Status: In production.

    Performance and correctness work on the platform’s multi-million-row tables.

    • One query on a 5.5M-row production table: 1,619 ms → 2.2 ms.
    • Rebuilt the funnel-metrics system after finding that every “last 2 weeks” metric was windowed on the wrong event.

  • Engineering tooling for a .NET shop

    Independent contract, Belgian software company (2025 to present)

    • GitLab CI
    • C#
    • Python
    • PostgreSQL
    • Claude Code

    Status: In production use.

    Tools other engineers depend on, built instead of repeating the task by hand.

    • Re-architected the company-wide GitLab CI/CD template library into composable, layered templates, and built the Windows Service deployment pipeline.
    • Authored the .NET client library for a centralised logging platform: about 6,300 lines including a Microsoft.Extensions.Logging provider and a full test suite. Claude Code assisted.
    • On the logging platform itself (Flask and PostgreSQL, co-developed): Alembic migrations, the log-retention service and cursor pagination.
    • Designed the MCP access layer that lets Claude Code and similar agents query the logging platform directly.
    • Wrote a Claude Code pre-commit hook that validates staged CI YAML before it is committed.

  • Stock and billing system for bonded alcohol storage

    Independent contract, Belgian software company (2019 to 2022)

    • C#
    • .NET 5
    • EF Core
    • SQL Server

    Status: Still in production.

    A stock and billing system for a bonded warehouse, built for a client of the software company.

    • Wrote the commissioned technical design (35 hours): the entity schema and the master ticket tree.
    • Then built the core: 61 tickets specified and built, on .NET 5, EF Core and SQL Server.

Personal projects

  • Bot844, a self-hosted Twitch chat bot

    Personal project, open source, 2024

    • Deno
    • TypeScript
    • Docker
    • AWS EC2

    A two-part application built on Deno and Fresh: a server-side service that connects to Twitch channels and reacts to events and chat messages, and a small website that handles the login flow for streamers.

    • New commands and localised, customisable strings can be added without touching the core.
    • Uses the Twitch API over WebSockets, with a fairly involved login flow, and stays connected reliably.
    • A CI/CD pipeline packages it as a small Docker image and deploys it to Amazon EC2.

    Built for a streamer friend, and to learn Deno and Fresh.