Build your own Invoice Simple with Claude Code

A quick invoice maker: create invoices from a template, send as PDF or link, mark paid and more.

WeekendA working first version in a day or two

The Claude Code prompt

Build my own take on Invoice Simple: a quick invoice maker. Give it an original name, logo, colours and copy, and do not use Invoice Simple's name, branding or assets.

Version one should have:
- Create invoices from a template
- Send as PDF or link
- Mark paid
- Online payments
- Client list

The hard part: Almost none. Make PDFs look great.

How to build it:
1. Read this folder first. If it is empty, set up Next.js (App Router, TypeScript, Tailwind) with Postgres through Prisma or Supabase, and Supabase Auth or Auth.js for sign-in. Write a short PLAN.md with the data model, screens, third-party services and what you are leaving out of version one.
2. Build the core loop end to end before anything else: create invoices from a template, working with real data saved to the database.
3. Add the rest of the features one at a time, and seed realistic demo data so every screen looks alive.
4. Keep API keys in environment variables, and put any paid service behind a small interface with a local stub, so the app runs on a fresh machine without accounts.
5. Run it, click through every screen on desktop and mobile widths, fix what breaks, and finish with a summary of what works, what is stubbed and how to deploy it.

Paste it into Claude Code in an empty folder. It plans first, so read PLAN.md and steer before it starts building.

Version one

  • Create invoices from a template
  • Send as PDF or link
  • Mark paid
  • Online payments
  • Client list

The hard part

Almost none. Make PDFs look great.

Make it yours: a niche Invoice Simple ignores, an original name and brand, and one feature it does badly done well.

More to build

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