Text highlight annotations are a vital feature for drawing attention to specific passages in PDFs and other documents, helping readers quickly locate essential information. Whether you need to flag key terms in a contract, annotate a section for review, or spotlight a critical paragraph in a report, highlighting streamlines reading and boosts comprehension. In this tutorial we’ll show you how to leverage the Cloud .NET SDK with the .NET REST API to add text highlight annotations to PDF documents, empowering your document‑processing workflows.

Steps to Add Text Highlight Annotation to PDF with .NET REST API

1. Sign up and get your API credentials from the GroupDocs Cloud Dashboard
2. Install GroupDocs.Annotation Cloud .NET SDK using the NuGet package
3. Initialize the Configuration class to set up your API credentials
4. Create an instance of the AnnotateApi class to add the annotations
5. Load the input PDF file from cloud storage with FileInfo
6. Create a text highlight annotation using AnnotationInfo
7. Configure annotation options with AnnotateOptions
8. Annotate the PDF with text highlight using the Annotate method

These steps ensure that you can add annotations and highlight text in PDF files in .NET with a highly customizable appearance, using just a few API calls. Additionally, developers can seamlessly automate the process of annotating PDFs in C# apps and accommodate large volumes of documents. Our cloud API provides all the flexibility you need so that you can focus on the core functionality of your application.

Code to Add Text Highlight Annotation to PDF with .NET REST API

With the .NET REST API, developers can add and customize text highlights to documents in just a few straightforward steps. This streamlined PDF annotation makes it an ideal choice for C# projects that need fast, reliable document review—whether for legal platforms, educational tools, or any application where highlighting specific text is essential. Whether you’re building a web, mobile, or desktop solution, built‑in text‑highlighting enhances the user experience and makes interacting with PDFs far more intuitive.