GroupDocs.Signature for .NET is a flexible library that allows developers to build new or enhance existing apps with electronic signature functionality. The library provides a flexible API and comprehensive controls for creating custom e-signature workflows of any complexity. Key features include:

1. Electronic Signature Capture Control. Provides users with options to sign documents either by uploading a scanned copy of their signature, typing a signature with custom font styles, or drawing a signature with a mouse, touch or a stylus. Handwritten signatures can be drawn and applied to a document right in a web-browser.

2. Multiple Document Formats Support. All documents are signed in PDF format for security. However, the library can convert over 50+ file formats to PDF, so that users can get them e-signed as well. Among supported file formats are: Microsoft Word, Excel, PowerPoint, Visio, OpenDocument, RTF, CSV, TXT, AutoCAD and many more.

3. Documents Security and Integrity. The library provides comprehensive anti-tampering and audit-trail functionality to ensure document integrity and guarantee signature authenticity. This allows you to build legally-binding electronic signature solutions that comply with the U.S. federal ESIGN Act and UETA Act.

4. Merge Fields Handling. When preparing documents for signature, users can add merge fields like ?Name?, ?Date?, ?Order value?, etc. Recipients can then complete them online, before applying a signature.

5. Easy-to-Follow Signature Workflows. Intuitive wizards guide users to get documents signed quickly and easily. Users can store templates for reuse; organize/archive signed documents; save recipient contacts; send email notifications and reminders.

GroupDocs.Signature for .NET can be integrated into any .NET project, including ASP.NET and console/desktop applications.