One person.Whole products.In production.
Badral Erdenebulgan, full-stack and mobile engineer in Ulaanbaatar. Seven products in production, three on the App Store, six of them running on a server I operate myself.
- Hamtragch · referral app for vitamin house doctors and pharmacistsACCEPTED
- bpay · all my mongolian bank accounts in one appRUNNING
- HQ · my own status board and ci/cdRUNNING
- Mondaa Group · web, backend and react native app for a sydney companySHIPPED
- Unity games · where it started: ping pong, btype and a tank gameSHIPPED
The big ones, in full.
Five products I run end to end, each one a whole business. Real screenshots from the stores, real numbers with their source next to them.
APlayhouseAccepted
Sole engineer: backend, admin CRM, customer app, storefront, payments, and the server · since 2024
Statement. A Mongolian e-commerce company that sells factory-price goods to group buyers and delivers across the city. Customers order in the app, pay with QPay, card or wallet, then pick up at a branch or get it delivered.
Solution
- Express 5 + Prisma + PostgreSQL backend with about 223 admin endpoints
- React CRM with 22 modules: orders, warehouse, delivery, returns, reports
- Flutter customer app Playhouse-Order, on the App Store since 2023
- Next.js CMS for staff, kiosk and ops tablet flows
- Customer wallet with XAC bank transfers over a VPN gateway
- QPay payments and ebarimt e-receipts
- The Ubuntu server everything runs on
Express 5PrismaPostgreSQLFlutterNext.jsReactBullMQQPayXAC
BTetgelegAccepted
Тэтгэлэг · Maintainer since August 2026: two Lambda APIs, the Flutter app, four web frontends · since 2026
Statement. Scholarship listings, student memberships with QPay and Apple payments, coupons and e-receipts. Built by Mezorn since 2017. In 2026 I took over the whole eight-repository estate and keep it running.
Solution
- Took over 8 repositories: 2 Serverless Lambda APIs, a Flutter app, 4 web frontends
- Rebuilt a fully local dev stack (Mongo, Redis, upload stub) so fixes can be tested before they ship
- Closed silent-failure bugs in the back office and the admin API
- Diagnosed a CDN image outage after the previous vendor migrated
Node.js LambdaServerlessMongoDBRedisFlutterNext.jsReact
CPhysiqueProAccepted
Backend, admin and app engineering for the founder · since 2025
Statement. Coaches sell courses, members track workouts, join challenges, earn XP and ranks, and book partner services. The platform takes a share of every sale, so the money paths had to be exact.
Solution
- NestJS + MongoDB backend, 579 tests across 103 suites
- Coach revenue share, wallet and withdrawals with race-safe transactions
- XP, ranks and rewards ledger; events, bookings and promo codes
- Private video delivery through signed URLs on a separate bucket
- Admin web app, plus a security sweep that closed 11 auth holes and 5 live data leaks
NestJSMongoDBPrismaFlutterCloudflare R2QPay
DHymdralAccepted
Хямдрал · Founder and only engineer · since 2026
Statement. A discount marketplace: sellers post deals, shoppers subscribe for 1000₮ a month, referrals earn wallet bonuses, and nightly imports pull live sales from the biggest retailers in the country.
Solution
- Express 5 + Prisma + PostgreSQL backend with QPay subscriptions and a referral wallet
- Flutter app with verify.mn SMS sign-in, on Google Play and TestFlight
- Flutter web admin with a drag-and-drop homepage builder
- Nightly importers for Nomin, BSB and Emart with real expiry dates
- Nightly database backups and surgical production deploys
Express 5PrismaPostgreSQLFlutterQPayverify.mn
EZakhialga AIAccepted
Захиалга · Founder and only engineer · since 2026
Statement. Mongolian shops sell through Facebook Pages and Messenger. Zakhialga AI answers customers in Mongolian, finds the product, takes the order, sends a QPay link, and tells the owner on Telegram when the money lands.
Solution
- NestJS + PostgreSQL backend with a Claude tool-calling loop
- Messenger webhooks with owner handoff and auto-pause when a human replies
- Catalog with trigram search, orders with guarded stock, QPay invoices
- Web storefront with categories, sale pricing and chat-back
- Partner API and a Dart SDK; PhysiquePro is the first partner on the marketplace
NestJSPostgreSQLPrismaClaude APIMessenger PlatformQPayNext.jsDart
Where the rigor comes from.
Three years of competitive programming before the first job: 77 rated contests on Codeforces, national and international olympiads with Erkhet Erdem. It is why the money paths in these products are transaction-safe and why the tests are green.
Submissions so far.
First job at seventeen. Sydney for the degree, steelfixing to pay for it. Back home, one company after another handed me the whole product.
- 2024 – nowPlayhouse · Full-stack engineer, sole IT
The whole e-commerce and logistics platform: backend, admin CRM, customer app, storefront, payments, and the server it runs on.
- 2025 – nowOwn products · Hymdral, Zakhialga AI, bpay, HQ
Products I own end to end, from Prisma schema to App Store listing, all running on my own VPS.
- 2024 – 2025IMN / 68 Zeeliin Tuv · App developer
Built the loan app in Flutter while helping on the backend. 10K+ installs on Google Play.
- 2023 – 2024Nomin E-Shop · Flutter developer
Shipped the NOMIN app to both stores. 100K+ installs on Google Play.
- 2022 – 2023Mondaa Group, Sydney · Mobile, backend and web developer
Started as a steelfixer while studying at UTS, then built their web, backend and React Native app.
- 2021U-Point · Backend developer
Express services for United Alliance. Where I learned real backend work.
- 2019Woovoo Technology · System specialist
First job at 17, right after high school. Python and Odoo ERP.
- 2022 – 2024University of Technology Sydney, BSc Computer Science
Finished the degree in Sydney while working.
- 2019 – 2021National University of Mongolia, BSc Computer Science
Started the degree during the pandemic, working at the same time.
- 2017 – 2019Erkhet Erdem
Three years of competitive programming, national and international olympiads.
Write to me.
If you need someone who can build the whole thing and keep it running, I am one email away. I answer the same day.