Hashmato: multi-tenant cloud POS

Hashmato is a cloud POS for food-and-beverage and retail operators. I worked on its backend: the payment gateway, the food-delivery integration service, the shared data-access layer, a pricing engine, and a stored-value ordering backend.

Every one of these runs per tenant, and each tenant can be configured differently.

In a multi-tenant POS, tenants don’t share a payment provider, a delivery partner, or a price list. One tenant takes Stripe, another PayNow QR. One sells on Grab, another on Deliveroo.

Money and orders also leave no room for partial failure. Webhooks can arrive more than once, partners retry, and refunds have to reconcile.

• Many providers, one checkout

  Each tenant can run a different payment provider, and the POS shouldn’t need to know which one.

• Partners that speak different protocols

  Delivery platforms each have their own menu formats, order flows, store status, and webhook security.

• Prices that depend on context

  The same item can cost different amounts by brand, location, channel, and time of day in the tenant’s timezone.

• Money that must always reconcile

  Wallets, auto-recharge, refunds, and partial cancellations all touch balances that must stay consistent.

• Adapters behind one interface

  Payment providers and delivery partners each implement a single interface. Webhooks are verified with HMAC (and OAuth2 where partners require it) and retried through BullMQ.

• Database per tenant, shared access layer

  Tenants keep separate PostgreSQL databases, while 30+ domain modules share one data-access layer for filtering, bulk upserts, export, and import.

• Batch the lookups

  The pricing engine’s first version looked up overrides per item. Batching them into one PostgreSQL query per page removed the N+1.

• Transactions and atomic counters

  Ordering uses PostgreSQL transactions for balances and ledgered refunds, and Redis Lua scripts for atomic queue numbers.

4payment providers behind one adapter

Stripe, Omise, PayNow QR, and an in-house gateway, chosen per tenant.

30+domain modules on one data-access layer

Database-per-tenant PostgreSQL with TypeORM.

1 queryper page for price overrides

Replaced an N+1 lookup in the pricing engine’s first version.

7NestJS microservices on Kubernetes delivery

Extended with Helm, helmfile, SOPS, and Traefik.

Figures come from my resume or from measuring the shipped product. Where a number describes the product or the team rather than my work, the context says so.

• NestJS
• TypeScript
• PostgreSQL
• TypeORM
• Redis
• BullMQ
• Docker
• Kubernetes
• Helm
• GitHub Actions

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