Skip to main content
The Invoice Generator API is built with Next.js App Router and provides RESTful endpoints for managing invoices, templates, and PDF generation.

​
Base URL

All API endpoints are relative to your application’s base URL: 
https://your-domain.com/api
For local development: 
http://localhost:3000/api

​
API structure

The API follows Next.js App Router conventions with route handlers located in app/api/. Each directory represents an endpoint: 
app/api/
├── auth/
│   ├── [...nextauth]/     # NextAuth.js authentication
│   └── register/          # User registration
├── invoices/
│   ├── route.ts           # GET, POST /api/invoices
│   └── [id]/
│       └── route.ts       # GET, PATCH, DELETE /api/invoices/:id
├── templates/
│   └── route.ts           # GET, POST /api/templates
├── pdf/
│   └── route.ts           # POST /api/pdf
└── email/
    └── route.ts           # POST /api/email

​
Request format

All API requests should use JSON formatting: 
curl -X POST https://your-domain.com/api/invoices \
  -H "Content-Type: application/json" \
  -d '{"invoiceNumber": "INV-001", "customer": "Acme Corp"}'

​
Response format

API responses are returned in JSON format with appropriate HTTP status codes.

​
Success response

{
  "message": "Invoice created successfully",
  "invoice": {
    "id": "550e8400-e29b-41d4-a716-446655440000",
    "invoiceNumber": "INV-001",
    "customer": "Acme Corp"
  }
}

​
Error response

{
  "error": "Missing required fields"
}

​
Status codes

The API uses standard HTTP status codes:
CodeDescription
200OK - Request succeeded
201Created - Resource created successfully
400Bad Request - Invalid request parameters
401Unauthorized - Authentication required
404Not Found - Resource not found
409Conflict - Resource already exists
500Internal Server Error - Server error
501Not Implemented - Feature not yet available

​
Available endpoints

Invoices

Create, read, update, and delete invoices

Templates

Manage invoice templates and designs

PDF generation

Generate PDF versions of invoices

Email

Send invoices via email

​
Runtime configuration

All API routes use the Node.js runtime for full access to server-side features:
app/api/auth/[...nextauth]/route.ts
export const runtime = "nodejs";

​
Error handling

All endpoints implement try-catch error handling:
app/api/invoices/route.ts
try {
  const body = await request.json();
  
  if (!body.invoiceNumber || !body.customer) {
    return NextResponse.json(
      { error: "Missing required fields" },
      { status: 400 }
    );
  }
  
  // Process request...
} catch (error) {
  return NextResponse.json(
    {
      error: error instanceof Error 
        ? error.message 
        : "Failed to create invoice"
    },
    { status: 500 }
  );
}

​
Next steps

Authentication

Learn how to authenticate API requests

Invoice endpoints

Explore invoice management endpoints

Build docs developers (and LLMs) love

Get started for freeTalk to us