Home Loan Application Demo

A comprehensive ASP.NET Core web application demonstrating a multi-step home loan application process with integrated electronic signatures using BoldSign API.

Overview

This demo showcases:

• Multi-step form with personal, employment, and loan information collection
• Embedded signature workflow using BoldSign for document signing
• Real-time document status tracking via webhooks
• Template-based document generation with pre-filled form fields
• Responsive UI with progress indicators and form validation

Prerequisites

Before running this application, ensure you have:

• .NET SDK 7.0 or later (Download)
• BoldSign Account with API access (Sign up)
• API Key from BoldSign account
• Template ID of your home loan template in BoldSign
• Webhook Secret Key for webhook signature validation

Getting Started

1. Clone the Repository

git clone <repository-url>
cd HomeLoanDemo

2. Set Up Environment Variables

Create a .env file in the project root (or set system environment variables):

APIKEY=your_boldsign_api_key_here
TEMPLATEID=your_template_id_here
WEBHOOKKEY=your_webhook_secret_key_here

Or set environment variables in your shell:

Windows (PowerShell):

[Environment]::SetEnvironmentVariable("APIKEY", "your_key", "User")
[Environment]::SetEnvironmentVariable("TEMPLATEID", "your_template_id", "User")
[Environment]::SetEnvironmentVariable("WEBHOOKKEY", "your_webhook_key", "User")

macOS/Linux (Bash):

export APIKEY="your_boldsign_api_key_here"
export TEMPLATEID="your_template_id_here"
export WEBHOOKKEY="your_webhook_secret_key_here"

3. Install Dependencies

dotnet restore

4. Run the Application

Development:

dotnet run

The application will start at https://localhost:7179 (or http://localhost:5183)

Production Build:

dotnet publish -c Release

Project Structure

HomeLoanDemo/
├── Controllers/
│   └── HomeController.cs          # Main application logic
├── Models/
│   ├── TemplateDetails.cs         # Form data model
│   └── ErrorViewModel.cs          # Error page model
├── Views/
│   ├── Home/
│   │   ├── Index.cshtml           # Main application form
│   │   ├── SignDocument.cshtml    # Document signing page
│   │   ├── SignCompleted.cshtml   # Completion confirmation
│   │   ├── _PersonalInfo.cshtml   # Personal details partial
│   │   ├── _EmploymentInfo.cshtml # Employment details partial
│   │   └── _LoanInfo.cshtml       # Loan details partial
│   └── Shared/
│       ├── _Layout.cshtml         # Main layout
│       └── Error.cshtml           # Error page
├── wwwroot/
│   ├── css/                       # Stylesheets
│   ├── js/                        # Client-side scripts
│   └── assets/                    # Images and fonts
├── Program.cs                     # Application startup
├── appsettings.json              # Configuration
└── HomeLoanDemo.csproj           # Project file

Features

Form Workflow

1. Personal Information - Collect name, date of birth, SSN, contact details
2. Employment Information - Gather employer details, job title, income
3. Loan Information - Capture loan amount, property details, loan purpose
4. Document Signing - Generate and display embedded signature link
5. Completion - Confirm signed document and provide download option

Key Technologies

• ASP.NET Core 7.0 - Web framework
• BoldSign API - Electronic signature integration
• Razor Views - Server-side templating
• Bootstrap - Responsive UI framework
• jQuery - Client-side interactions

Configuration

Key settings in appsettings.json:

• AllowedHosts - Configure for your deployment domain
• Logging - Adjust log levels for debugging

Webhook Integration

The application includes a webhook endpoint (/Home/Webhook) to track document signing completion:

• Endpoint: POST /Home/Webhook
• Signature Validation: All webhook requests are validated using the WEBHOOKKEY
• Completion Tracking: Signed documents are cached for download availability

Files of Interest

• Controllers/HomeController.cs - Contains document creation, signing, and webhook handling logic
• Views/Home/_LoanInfo.cshtml - Loan details form with numeric input validation
• Views/Home/Index.cshtml - Main multi-step form with progress tracking
• Models/TemplateDetails.cs - Data model for loan application form

Error Handling

The application includes:

• Null reference validation for environment variables
• Try-catch blocks for API operations
• User-friendly error messages
• Logging for debugging

Security Considerations

✅ Best Practices Implemented:

• Environment variables for sensitive data (API keys, secrets)
• Webhook signature validation using BoldSign's WebhookUtility.ValidateSignature()
• HTTPS enforcement in production via app.UseHttpsRedirection() and HSTS
• CSRF token protection on all POST forms using @Html.AntiForgeryToken()
• Input validation on form fields with HTML5 attributes and client-side validation
• Null reference checks for safe environment variable handling
• Exception handling for API operations with user-friendly error messages

Troubleshooting

"Template ID is not configured"

• Ensure the TEMPLATEID environment variable is set correctly
• Verify the template exists in your BoldSign account

Webhook validation failed

• Check that the WEBHOOKKEY environment variable matches your BoldSign webhook secret
• Verify webhook headers are being sent correctly

API connection errors

• Confirm your APIKEY is valid and has appropriate permissions
• Check your internet connection

Support

For issues with BoldSign API:

• BoldSign Documentation
• BoldSign Support

License

This demo application is provided as-is for learning and demonstration purposes.

Next Steps

• Customize the loan application form to match your requirements
• Add additional form fields to the template in BoldSign
• Deploy to Azure App Service or your preferred hosting platform
• Integrate with your backend loan processing system