Hi everyone!
I've been working on QuantumBilling, an open-source GST billing application designed for small and growing businesses in India.
The idea behind the project is to simplify everyday invoicing, billing, and GST-related workflows while exploring how Elixir and Phoenix can be used to build practical business applications.
What QuantumBilling includes
GST invoicing — CGST, SGST, and IGST calculations
Customer management — Manage clients and their billing information
Invoice customization — Customizable templates and PDF generation
Recurring billing — Automated recurring invoice workflows
Payments — UPI QR codes and Razorpay payment links
E-invoicing and E-Way Bills — Integration workflows for Indian GST requirements
Multi-business support — Separate PostgreSQL schemas for individual businesses
Reports and reminders — Billing reports and GST compliance reminders
Tech Stack
Elixir — Application and business logic
Phoenix LiveView — Interactive, real-time user interfaces
PostgreSQL + Ecto — Database and multi-business data management
Oban — Background jobs, scheduled tasks, and recurring workflows
One of the interesting technical challenges has been implementing multi-business architecture using separate PostgreSQL schemas while keeping user accounts and business memberships shared.
The project also uses Phoenix PubSub for real-time updates and Oban for background processing.
Current Status
QuantumBilling is still under active development. The core billing workflows are being developed and improved, while some external integrations currently use sandbox or simulated behavior.
There's still plenty of room for improvements in architecture, UI/UX, testing, documentation, and functionality.
Open to Community Contributions
I'm sharing this project here because I'd love to hear feedback from the Elixir community.
If something in the architecture could be improved, you've encountered similar challenges, or you have suggestions for making the application better, I'd be happy to discuss them.
The repository is public, and contributions through issues and pull requests are welcome.
GitHub Repository:
https://github.com/phravins/QuantumBilling
I'm particularly interested in hearing how others approach multi-tenant applications, background job processing, and complex business workflows using Elixir and Phoenix LiveView.
Looking forward to your thoughts and suggestions!
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