--- title: "Extract data from invoices with C# | Nutrient .NET SDK" canonical_url: "https://www.nutrient.io/guides/dotnet/extraction/invoices/" md_url: "https://www.nutrient.io/guides/dotnet/extraction/invoices.md" last_updated: "2026-05-21T17:12:02.203Z" description: "Learn how to extract data from invoices using C# and Nutrient .NET SDK’s (formerly GdPicture.NET) optical character recognition (OCR) engine with key-value pair recognition." --- # Extract invoice data with C# and OCR Nutrient.NET SDK’s (formerly GdPicture.NET) key-value pair (KVP) extraction engine enables you to recognize related data items in a document and export them to an external destination like a spreadsheet. To extract data items from an invoice, follow the steps below: 1. Create a `GdPictureOCR` object and a `GdPictureImaging` object. 2. Select the invoice by passing its path to the `CreateGdPictureImageFromFile` method of the `GdPictureImaging` object. 3. Configure the OCR process with the `GdPictureOCR` object in the following way: - Set the invoice with the `SetImage` method. - Set the path to the OCR resource folder with the `ResourceFolder` property. The default language resources are located in `GdPicture.NET 14\Redist\OCR`. For more information on adding language resources, see the [language support] guide. - With the `AddLanguage` method, add the language resources that Nutrient.NET SDK uses to recognize text in the image. This method takes a member of the `OCRLanguage` enumeration. 4. Run the OCR process with the `RunOCR` method of the `GdPictureOCR` object. 5. Get the number of key-value pairs detected during the OCR process with the `GetKeyValuePairCount` method of the `GdPictureOCR` object, and loop through them. 6. Get the key-value pairs, the data types, and the confidence scores with the following methods: - [`GetKeyValuePairKeyString`](https://www.nutrient.io/api/gdpicture/GdPicture.NET.14.API~GdPicture14.GdPictureOCR~GetKeyValuePairKeyString.html) - [`GetKeyValuePairValueString`](https://www.nutrient.io/api/gdpicture/GdPicture.NET.14.API~GdPicture14.GdPictureOCR~GetKeyValuePairValueString.html) - [`GetKeyValuePairDataType`](https://www.nutrient.io/api/gdpicture/GdPicture.NET.14.API~GdPicture14.GdPictureOCR~GetKeyValuePairDataType.html) - [`GetKeyValuePairConfidence`](https://www.nutrient.io/api/gdpicture/GdPicture.NET.14.API~GdPicture14.GdPictureOCR~GetKeyValuePairConfidence.html) 7. Write the output to the console. 8. Release unnecessary resources. The example below retrieves key-value pairs from the following invoice. [Download the sample invoice](/images/guides/dotnet/extraction/key-value-pairs/invoice.png) and run the code below, or [check out our demo](https://www.nutrient.io/demo/data-extraction). = ### C# ```csharp using GdPictureOCR gdpictureOCR = new GdPictureOCR(); using GdPictureImaging gdpictureImaging = new GdPictureImaging(); // Load the source document. int imageId = gdpictureImaging.CreateGdPictureImageFromFile(@"C:\temp\source.png"); // Configure the OCR process. gdpictureOCR.ResourceFolder = @"C:\GdPicture.NET 14\Redist\OCR"; gdpictureOCR.AddLanguage(OCRLanguage.English); gdpictureOCR.SetImage(imageId); // Run the OCR process. string ocrResultId = gdpictureOCR.RunOCR(); string keyValuePairsData = ""; for (int pairIndex = 0; pairIndex < gdpictureOCR.GetKeyValuePairCount(ocrResultId); pairIndex++) { keyValuePairsData += $"| Key: {gdpictureOCR.GetKeyValuePairKeyString(ocrResultId, pairIndex)} | " + $"Value: {gdpictureOCR.GetKeyValuePairValueString(ocrResultId, pairIndex)} | " + $"Document Type: {gdpictureOCR.GetKeyValuePairDataType(ocrResultId, pairIndex).ToString()} | " + $"Confidence Level: {Math.Round(gdpictureOCR.GetKeyValuePairConfidence(ocrResultId, pairIndex), 1).ToString()}% |\n"; } // Write the output to the console. Console.WriteLine(keyValuePairsData); // Release unnecessary resources. gdpictureImaging.ReleaseGdPictureImage(imageId); gdpictureOCR.ReleaseOCRResults(); ``` ### VB.NET ```vb Using gdpictureOCR As GdPictureOCR = New GdPictureOCR() Using gdpictureImaging As GdPictureImaging = New GdPictureImaging() ' Load the source document. Dim imageId As Integer = gdpictureImaging.CreateGdPictureImageFromFile("C:\temp\source.png") ' Configure the OCR process. gdpictureOCR.ResourceFolder = "C:\GdPicture.NET 14\Redist\OCR" gdpictureOCR.AddLanguage(OCRLanguage.English) gdpictureOCR.SetImage(imageId) ' Run the OCR process. Dim ocrResultId As String = gdpictureOCR.RunOCR() Dim keyValuePairsData = "" For pairIndex As Integer = 0 To gdpictureOCR.GetKeyValuePairCount(ocrResultId) - 1 keyValuePairsData += $"| Key: {gdpictureOCR.GetKeyValuePairKeyString(ocrResultId, pairIndex)} | Value: {gdpictureOCR.GetKeyValuePairValueString(ocrResultId, pairIndex)} | Document Type: {gdpictureOCR.GetKeyValuePairDataType(ocrResultId, pairIndex).ToString()} | Confidence Level: {Math.Round(gdpictureOCR.GetKeyValuePairConfidence(CStr(ocrResultId), CInt(pairIndex)), CInt(1)).ToString()}% |" & vbLf Next ' Write the output to the console. Console.WriteLine(keyValuePairsData) ' Release unnecessary resources. gdpictureImaging.ReleaseGdPictureImage(imageId) gdpictureOCR.ReleaseOCRResults() End Using End Using ``` = #### Used methods and properties - [`AddLanguage`](/api/gdpicture/GdPicture.NET.14.API~GdPicture14.GdPictureOCR~AddLanguage.html) - [`CreateGdPictureImageFromFile`](/api/gdpicture/GdPicture.NET.14.API~GdPicture14.GdPictureImaging~CreateGdPictureImageFromFile.html) - [`GetKeyValuePairKeyString`] - [`GetKeyValuePairValueString`] - [`GetKeyValuePairDataType`] - [`GetKeyValuePairConfidence`] - [`ReleaseGdPictureImage`](/api/gdpicture/GdPicture.NET.14.API~GdPicture14.GdPictureImaging~ReleaseGdPictureImage.html) - [`ReleaseOCRResults`](/api/gdpicture/GdPicture.NET.14.API~GdPicture14.GdPictureOCR~ReleaseOCRResults.html) - [`ResourceFolder`](/api/gdpicture/GdPicture.NET.14.API~GdPicture14.GdPictureOCR~ResourceFolder.html) - [`RunOCR`](/api/gdpicture/GdPicture.NET.14.API~GdPicture14.GdPictureOCR~RunOCR\(\).html) - [`SetImage`](/api/gdpicture/GdPicture.NET.14.API~GdPicture14.GdPictureOCR~SetImage.html) #### Related topics - [Load a file](/guides/dotnet/load-a-file.md) - [Save a file](/guides/dotnet/save-a-file.md) Format the output to obtain the following table: | Key | Value | Document type | Confidence level | | -------------------------- | ------------------------------------------------- | ------------- | ---------------- | | Billing date | 20/09/2022 | DateTime | 100% | | Order date | 20/09/2022 | DateTime | 100% | | Republic of PDF | +100 847 738 227 | PhoneNumber | 77.2% | | IBAN | AT13 2060 4236 6111 5994 | IBAN | 100% | | Customer | Vandelay Industries Around the Corner 13 NBC City | String | 69.8% | | Delivery address | Vandelay Industries Around the Corner 13 NBC City | String | 69.9% | | Invoice number | No 00162 | String | 70.9% | | Ref. number | 34751 | Number | 92.9% | | No | 00162 | Number | 100% | | Reference | P00201 | UID | 100% | | Quantity total (excl. VAT) | 320.00€ | Currency | 59% | | Subtotal | 1,220.00€ | Currency | 100% | | Discount (10%) | -122.00€ | Currency | 90.6% | | VAT (5.5%) | +6710€ | Currency | 66.9% | | Shipping cost | 0.00€ | Currency | 75% | | TOTAL | 1,165.10€ | Currency | 100% | | Description | Lake Mirror | String | 99.6% | | VAT | 5.5% | Percentage | 66.6% | | Price per unit (excl. VAT) | 320.00€ | Currency | 80% | | Tax No. | AT98765321 | UID | 73.8% | | \# | infe@bruuuk.com | EmailAddress | 65.6% | | \# | www.bruuuk.com | URL | 65.6% | --- ## Related pages - [Extract data from bank statements using C#](/guides/dotnet/extraction/bank-statements.md) - [Extract file attachments from PDFs in C#](/guides/dotnet/extraction/file-attachments.md) - [Extract images from PDFs in C#](/guides/dotnet/extraction/images.md) - [Effortlessly extract data from PDFs and images](/guides/dotnet/extraction.md) - [Check OCR and MICR data extraction using C#](/guides/dotnet/extraction/micr.md) - [Extract tables from PDFs and images using C#](/guides/dotnet/extraction/tables.md)