Table of Contents
Overview
You will learn how to build a web app that lets users chat with an assistant to collect invoice data, preview the invoice in real time, generate a PDF using an external API, and email it through Gmail.
User Flow:
- User Input
- Chat UI
- Collect Details
- Preview Invoice
- Edit and Regenerate
- Email it to the client or download as PDF
Technology Stack
Frontend
| Tool | Purpose |
|---|---|
| React | UI framework |
| Vite | Dev server and bundler |
| Tailwind | Styling system |
| Shadcn UI | Components (dialog, input, cards) |
| Framer Motion | Animations |
| Lucide React | Icons |
| Sonner | Toasts and alerts |
Backend
| Tool | Purpose |
|---|---|
| FastAPI | Backend framework |
| Motor | MongoDB driver |
| Pydantic | Validation |
| Requests | External API calls |
Database
| Tool | Purpose |
|---|---|
| MongoDB | Store drafts |
APIs and Required Services
Invoice Generation API
| Feature | Details |
|---|---|
| Format | PDF or UBL |
| Pricing | Free up to 100 invoices per month |
| Output | Professional invoice PDF |
| Key Fields | Items, tax, discounts, shipping, notes, currency |
Provided by Invoice-Generator.com.
How to Get API Access
- Visit https://invoice-generator.com/developers
- Create a free account
- Copy your API key from the dashboard
- Share it with Neo (Emergent's Agent) and it will add it to the backend.
Step
| Step | Action |
|---|---|
| 1 | Visit https://invoice-generator.com/developers |
| 2 | Create an account |
| 3 | Copy your API key from the dashboard |
| 4 | Add it to your backend .env file |
Gmail API (for sending invoices)
You will integrate Gmail so users can email invoices directly.
How to Get API Access
- Go to Google Cloud Console
- Create a new project
- Open API Library and enable Gmail API
- Create OAuth credentials
- Add redirect URIs for dev and production
- Copy Client ID and Client Secret
- Share it with Neo (Emergent's Agent) and it will add it to the backend.
Core Features
| Feature | Description |
|---|---|
| Conversational Input | AI-style chat that replaces traditional forms |
| Quick Choice Chips | Fast selection for currency, date, items and tax |
| Real Time Summary | Assistant prints totals, taxes and due amounts |
| PDF Preview | Base64 embed or download |
| Email Invoice | Gmail integration with OAuth |
| Save Draft | Store invoice data per user |
Final Notes
You now have a clear plan for building a smart invoice app that uses:
- A conversational UI
- A professional PDF generator
- Gmail email delivery
- A modern React interface
Check out the polished version of the app we made right here:
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