SardorbekAxadjonov

Owned the markup / commission engine — 7 layered markup scopes (platform, country, aggregator, hotel, service, agency, agency-group), each percent or fixed, with coupons and loyalty unified into one discount pipeline. Froze the booking-time total so the quote is charged unchanged at payment; integrated GoGlobal, TBO, and Dida. Built the admin-panel backend solo, including hierarchical RBAC where a sub-admin inherits the creator's permissions and can never exceed them.

Built the backend for four role-based app surfaces — role × module × action permissions with per-company scoping, trip / vehicle assignment, multi-device sessions, analytics, Yandex geocoder. GPS points arrive every 20 s and buffer in Redis; a point joins the trip history only when it moves past a configurable distance (~50 m) from the last fix, otherwise it is stored as a stop point in Postgres. Load-tested to 700 RPS with k6.

Built the ordering service — native Go PDF invoicing, Click and Payme, WebP / CDN catalog image pipeline, Firebase Cloud Messaging fan-out. AI image search: a vision model reads brand and part from a photo, matched by vector similarity so the buyer lands straight on the matching parts catalog. Load-tested to 500 RPS with k6.

Sole backend for the web-admin and mobile REST APIs — phone-OTP + JWT auth with Casbin RBAC, Firebase push, a Telegram ops bot, and a YouTube→S3 video pipeline (yt-dlp with a PO-token sidecar to clear bot checks without cookies) served through a CDN. Click Merchant API with MD5-signed, row-locked idempotent handlers (SELECT … FOR UPDATE) so retried callbacks never double-charge or double-enrol. Promo-code engine — percent / fixed, per-user and total caps, validity windows, per-course scope — enforced by a redemptions ledger with partial unique indexes and cancel / expire release triggers. Versioned Redis cache: an entity:version counter bumped on every write is folded into the cache key, so stale lists expire by TTL with no SCAN / KEYS.

In production: 8,000+ users (3,000+ active) · 70+ courses, 1,500+ lessons, 1,400+ videos · 2,000+ paid orders · 420M+ UZS processed