How to Connect to QuickBooks Online in .NET With C#

Why dotConnect for QuickBooks Online?

Easy integration with QuickBooks Online

dotConnect makes it easy for .NET applications to connect to QuickBooks Online and access accounting data like customers, invoices, and payments without dealing with API complexity.

Interactive OAuth token generation

dotConnect supports authentication via Interactive OAuth with a browser-based login flow for users. After authorization, it automatically obtains and manages access and refresh tokens.

User-friendly ADO.NET classes

The data provider uses standard ADO.NET data access classes, letting developers interact with QuickBooks Online data using familiar connection, command, and data reader patterns.

Advanced ORM Support

dotConnect supports popular .NET ORM technologies, including EF Core, Dapper, NHibernate, and LinqConnect, for QuickBooks Online data modeling.

Full ADO.NET Compliance

Established ADO.NET interfaces and conventions ensure reliable integration with existing .NET applications and development workflows.

Support & frequent updates

Dedicated technical support, comprehensive documentation, and regular updates ensure compatibility with QuickBooks Online services and .NET platforms.

Download and activate dotConnect for QuickBooks Online

You can start using dotConnect for QuickBooks Online immediately with a 30-day free trial. Choose one of the following installation options:

30-day free trial version

dotnet add package Devart.Data.QuickBooks

Install-Package Devart.Data.QuickBooks

Start using dotConnect for QuickBooks Online in your project today with a free trial

Free 30-day trial

Establish the connection

dotConnect for QuickBooks Online uses an interactive OAuth authorization flow to obtain access tokens and establish a connection with the data source. This approach enables secure data access without requiring the application to handle user credentials.

When a connection is opened for the first time, the provider launches a browser window, prompting the user to complete the authorization process. Once authorization is granted, the access tokens are securely stored, and subsequent connections can be established without additional user interaction. You only need to provide a valid license key.

This interactive authentication flow improves security while giving users full control over access permissions.

Here is the sample code that will help you connect to QuickBooks Online. Complete it with the following credentials: Client Id, Company Id, Client Secret, Refresh token, and License key. Additionally, set Sandbox to true if you are using the sandbox application type.

using System.Data;
using Devart.Data.QuickBooks;

class Program
{
  static void Main()
  {
    using QuickBooksConnection conn = new(
      "Authentication Type=OAuthInteractive;" +
      "License Key=**********");
    conn.Open();

    using QuickBooksCommand cmd = new(
      "SELECT Id, Name, FullyQualifiedName, Description FROM Account", conn);

    using QuickBooksDataReader reader = cmd.ExecuteReader();

    if (!reader.HasRows)
    {
      Console.WriteLine("No data found in the Account table.");
      return;
    }

    while (reader.Read())
    {
      string id          = reader["Id"]?.ToString()                 ?? "N/A";
      string name        = reader["Name"]?.ToString()               ?? "N/A";
      string fqn         = reader["FullyQualifiedName"]?.ToString() ?? "N/A";
      string description = reader["Description"]?.ToString()        ?? "N/A";

      Console.WriteLine($"Id:                 {id}");
      Console.WriteLine($"Name:               {name}");
      Console.WriteLine($"FullyQualifiedName: {fqn}");
      Console.WriteLine($"Description:        {description}");
      Console.WriteLine(new string('-', 50));
    }
  }
}

Once you successfully connect your application to QuickBooks Online, you will be able to fetch and manage your data.

Connection string examples

In .NET applications, a connection string is a formatted string that provides the information required to establish a connection to a data source.

At its core, the connection string tells the provider where to connect, how to authenticate, and what settings to use during the connection process. Once supplied, the data provider parses the string, validates its syntax, and ensures that all specified keywords are supported. After this initial validation, the extracted parameters are passed to the data source, which performs additional checks and ultimately establishes the connection.

The table below outlines some of the most commonly used connection string parameters.

For a complete list of parameters and detailed descriptions, refer to the official guidelines.

Conclusion

You can now connect your C# application to QuickBooks Online using dotConnect for QuickBooks. With the connection in place, you can extend your application to perform a wide range of operations, such as querying customers, invoices, and accounts, as well as creating, updating, and managing QuickBooks data programmatically.

And if you want firsthand experience, feel free to download dotConnect for QuickBooks Online for a free 30-day trial. Give it a go under the real workload!

FAQ