Billing SaaS
BillBook
Full-stack developer, freelance for Hench Solutions
Built for businesses that need an auditable paper trail. Teams draft and finalize GST invoices (finalized ones are immutable), track parties, payments, credit notes and stock in append-only ledgers, and export GST and report CSVs. I built the Express, PostgreSQL and Drizzle API and the Next.js app, with OTP login, JWT, audit logs and OpenAPI docs.
What it does
- Finalized GST invoices are immutable, so the paper trail stays auditable.
- Append-only ledgers for parties, payments, receipts, credit notes and stock.
- GST and report CSV exports.
- OTP login, JWT, audit logs and OpenAPI docs on an Express, PostgreSQL and Drizzle API.
Tech stack
- Next.js
- TypeScript
- Express
- PostgreSQL
- Drizzle ORM
- AWS