Open Source Billing System Build

I’m putting together a lightweight, open-source billing web /IOS/Android app and need a developer who can deliver a first working version I can share publicly.

Core flow
• Secure login page with user/role management.
• Initial business-type picker (Retail or Services) that stores the choice in the user profile.
• Separate dashboards for each type, showing a quick summary of today’s sales, expenses, and outstanding credits.

Key modules
1. Billing & invoicing – create, edit, and save invoices; one-click “Send bill to WhatsApp” using the official WhatsApp Cloud API or an equally reliable gateway.
2. Reports – downloadable Sales, Expense, and Customer reports (CSV or PDF).
3. Creditors – simple ledger to track who owes what and due dates.
4. Expenses manager – log daily expenses and have them reflected instantly in the dashboard and reports.

Project expectations
• Clean, readable code under an OSI-approved licence.
• Clear setup guide (Docker, or step-by-step commands) so anyone can run it locally.
• Modular structure that lets me add more business types later without rewriting everything.
• Basic but responsive UI—Bootstrap, Tailwind, or similar is fine.

Deliverables
- Source code repository with commit history
- Database schema or migration scripts
- Brief README covering installation, environment vars, and how to trigger WhatsApp sending in a sandbox

With the current budget I’m aiming for a minimal viable build: solid authentication, the two dashboards, functional invoice generation, WhatsApp send, and the three report downloads. If you can get that done efficiently, we’ll plan phase two together.