Yang Yanginternal software

Yang Yang

I build the internal systems small businesses run on day to day — quoting, invoicing, approvals and bookkeeping. The unglamorous software that replaces a folder of spreadsheets.

Taking on new work now

Selected work

An invoicing and bookkeeping system for a travel agency

Guideyuk sells tours to companies and groups in Indonesia. Its consultants wrote every quotation by hand and sorted out the money afterwards. I built the system they now run the office on — quotations and invoices, printable A4 documents, payment tracking, and the bookkeeping behind it.

  • React
  • TypeScript
  • Postgres
  • Supabase
  • PDF generation
Read the case study

About

I work on software that a handful of people use every single day, where a small mistake shows up as a wrong invoice rather than a dip in a metric. That tends to mean careful data modelling, permissions that hold up under pressure, and interfaces shaped like the paperwork people already know.

I spent years as a senior backend engineer before moving into freelance work, where my focus now is internal software and AI automation.

Based in Jakarta. Happy to work remotely.

Focus
Internal software & AI automation
Usually
React, TypeScript, Postgres
Availability
Freelance / project work

Get in touch

If you have a process held together by spreadsheets and habit, tell me about it. A short description of what your team does by hand is enough to start.