full-stack & backend engineer

Haider
Zaman

I design and ship real-time backend systems — bidding engines, fraud detection pipelines, identity services — and lately, AI agents that help operate them. Based in Islamabad, working with teams worldwide.

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whoami.sh

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nameHaider Zaman
roleBackend / Full-Stack Engineer
based_inIslamabad, Pakistan
statusaccepting new contracts
stackGo · TypeScript · Python · Kotlin
focusad-tech systems, AI agents

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real-time bidding tuned for <200ms response· Top Rated · 5.0★ on Upwork· shipped apps with 10K+ installs· full programmatic ad-tech stack, built end to end

about

Backend-first, full-stack when it counts.

I started at CodeFreaks building B2B SaaS products from the ground up — a hiring platform for private equity firms, a UK vehicle recovery marketplace — then moved into ad-tech at Advergic, where I built the full programmatic advertising stack: bidding, fraud detection, identity resolution, an Android SDK, and the dashboards that tie it together.

Most of what I build lives where latency, scale, and correctness all matter at once — request paths measured in milliseconds, pipelines processing real-time signal, systems that have to be right the first time. Lately that's extended to agentic AI: I'm building a copilot that investigates and fixes infrastructure issues on its own, with a human approving the risky parts. Outside client work, I freelance on Upwork as a Top Rated contractor.

experience

Where the systems got built.

In chronological order — each role building on the last.

advergic Full-Stack Developer 2025.04 → present
  • Built a real-time bidding engine in Go (Gin, OpenRTB 2.x) tuned for sub-200ms response at scale
  • Migrated a bot & invalid-traffic detection platform from Node/Redis Streams/MongoDB/ClickHouse to Go for throughput
  • Shipped an Android SDK (Kotlin, Prebid header bidding, GAM mediation) with on-device fraud detection and OpenTelemetry instrumentation
  • Built an identity & cookie-sync service integrating LiveRamp, ID5, UID2 and TCF 2.0 consent, backed by Aerospike + Redis
  • Wrote a ~22KB vanilla JS tracking pixel covering the full ecommerce funnel and multi-source attribution
  • Delivered publisher, advertiser and admin dashboards, plus a self-hosted Prebid Server bidder adapter
codefreaks Software Engineer 2024.01 → 2025.04
  • Dexta (dexta.io) — B2B SaaS hiring platform for private equity firms, built on NestJS/MySQL/Stripe
  • Winchit (winchit.co) — UK vehicle recovery marketplace on Node.js/MongoDB/WebSockets/Stripe
  • Contract: a live NFC-based loyalty app for TaskDONE UG (MERN) — 10K+ downloads, 4.3★ on Google Play
freelance Independent Contractor · Upwork 2024.10 → present
  • Top Rated, 5-star client ratings across every engagement
  • Delivery across SaaS platforms, live streaming, automation and enterprise integration work

selected work

Systems, named the way I'd name them in a repo.

sre-copilot in development

An AI SRE/DevOps copilot — connect your servers, ask questions in plain English, and let it investigate autonomously. Remediation only runs after a human approves it. Multi-service: Node/Express/PostgreSQL backend, a Python/LangGraph agent engine, a React frontend, and a Go remote agent.

Node.jsPostgreSQLPythonLangGraphReactGo
realtime-bidding-engine live

An OpenRTB-compliant bidder built for sub-200ms response under real production load.

GoGinOpenRTB 2.x
ivt-detection-platform live

Bot & invalid-traffic detection for ad inventory, rebuilt in Go for throughput.

GoClickHouseRedis
android-bidding-sdk live

Header-bidding & mediation SDK with on-device fraud detection and full telemetry.

KotlinPrebidOpenTelemetry
identity-resolution-service live

Cookie-sync & identity matching across LiveRamp, ID5, UID2, with TCF 2.0 consent handling.

GoAerospikeRedis
dexta live

B2B SaaS hiring platform built for private equity firms. dexta.io

NestJSMySQLStripe
winchit live

A marketplace connecting UK drivers with vehicle recovery services in real time. winchit.co

Node.jsMongoDBWebSockets
loyalty-nfc-app live

NFC-based loyalty app for TaskDONE UG — 10K+ downloads, 4.3★ on Google Play.

MERNNFC

stack

What's actually in the manifest.

languagesGo · TypeScript / JavaScript · Kotlin · Python
backendNode.js / Express · NestJS · Gin
dataPostgreSQL · MySQL · MongoDB · ClickHouse · Redis · Aerospike
frontend & mobileReact · React Native · Kotlin / Android
ad-techOpenRTB 2.x · Prebid · TCF 2.0
ai & infraLangGraph · AI agents · OpenTelemetry · Docker · BullMQ

contact

Let's build something that has to work.

Open to contract and full-time backend / full-stack roles — especially systems with real scale or latency constraints.

Send an email View GitHub Connect on LinkedIn
contact.sh
emailhaiderzamanusafxay@gmail.com
phone+92 341 8857731
linkedin/in/haiderzamanyzi
github/haideryzai