Multi-tenant SaaS, financial ERPs, real-time platforms and mobile apps, designed, shipped and operated in production. Product engineer and co-founder of CodeMines.
Selected work
Six of the 17 products I've built. Every one has a real client, real money moving through it, and either a link you can open or a reason it's confidential.
How I build
How one request can't reach another shop's data. Every node is something that exists in production code today.
Access token
The organization a caller belongs to is carried in the signed access token. Controllers never read organizationId from a request body, a header or a query string. Those are all under the client's control. If you can't forge the token, you can't claim another shop.
// Controllers derive tenant from AuthContext, never from the request.
export interface AuthContext {
userId: string;
organizationId: string;
membershipId: string;
role: Role;
branchId: string;
allowedBranchIds: string[];
canAccessAllBranches: boolean;
terminalId: string | null; // set when a paired till fixes the branch
permissions: Set<Permission>;
}What I build
Each one links to a case study where I did exactly that.
Multi-tenant products with real permission models, billing, reporting and the operational back office behind them. NestJS and PostgreSQL behind Next.js.
Inventory, sales, purchasing and accounting where the numbers have to reconcile. Integer money, lot costing, double-entry ledgers, append-only history.
React Native and Expo apps that ship (maps, payments, real-time, on-device ML) and the backends they talk to. Five on the App Store and Play Store.
The part after shipping. Docker images to GHCR, SSH deploys to a VPS behind nginx, GitHub Actions for CI, and runbooks as workflows so production can be diagnosed without me.
Process
Four stages, each with a concrete deliverable at the end.
What the product has to do, who pays, what breaks if it's wrong.
Data model, boundaries, the security model, what's deliberately out of scope.
Small reviewable diffs, tests that run against a real database, written updates.
CI to a real environment, store submission, a runbook you can operate without me.
Writing
Engineering notes from real products. The code is private; the thinking isn't.
Writing
About
Three years of shipping products end to end: a contract at an IPTV business, independent product work, a year at SparkTech Agency, and now CodeMines, the studio I co-founded. 1,660 commits across 81 repositories, most of it multi-tenant SaaS, financial systems and mobile apps that real businesses run on. I work in TypeScript across the whole stack, I measure before I change things, and I don't ship code I can't explain line by line.
More about meTwo or three sentences is enough. I'll come back with what I'd do, how long it takes and what it costs.