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Download C# Library for Searching & Indexing via .NET API

GroupDocs.Search for .NET is a fascinating document search API. It extracts text and metadata from documents and performs advance searching and indexing operations on the basis of fuzzy and synonym algorithms. API also supports full text search. Information retrieval on the basis of full text search is based on indexes. All documents having at least one match in phrases, para or words will be listed as a result.

Release Notes Download

Get Started

Open NuGet package manager, search for GroupDocs.Search and install. You may also use the following command from the Package Manager Console.

Install

To install please execute Install-Package GroupDocs.Search from Package Manager Console in Visual Studio to fetch & reference GroupDocs.Search assembly in your project.

PM>

     Install-Package GroupDocs.Search

Update

If you already have GroupDocs.Search for .Net and want to upgrade it, please execute Update-Package GroupDocs.Search to get the latest version.

PM>

     Update-Package GroupDocs.Search

Advanced Document Search & Indexing .NET API

GroupDocs.Search for .NET is a comprehensive library enabling developers to build advanced search and indexing capabilities into their .NET applications. It supports a wide range of document formats and provides features such as semantic search, entity recognition, sentiment analysis, and custom entity extraction. With its flexible API and support for various search types, developers can easily implement powerful search functionalities, enhance data analysis, and gain valuable insights from their documents.

Creating an Index

Index Directory
Specify a directory where index data will be stored.

Memory-Based Indexing
Option to create an index in memory for faster search (but not persistent).

Adding Documents to an Index

Individual Files
Add files one by one using their paths.

Directory Scanning
Add all supported documents within a specified directory and its subdirectories.

File Streams
Index documents directly from streams for flexibility.

Updating and Maintaining an Index

Incremental Updates
Add or remove individual documents without rebuilding the entire index.

Index Optimization
Improve search performance by optimizing the index structure periodically.

Index Backup and Restore
Create backups of the index for safety and restore them if needed.

Basic Search Functionality

Full-Text Search
Index and search within the body text of documents.

Metadata Search
Search based on document metadata (author, title, keywords, etc.).

Supported File Formats
Search across various file types (DOCX, PDF, HTML, etc.).

Simple Query Syntax
Use basic search terms and phrases.

Advanced Search Options

Boolean Operators
Combine search terms using AND, OR, NOT for precise queries.

Wildcards
Use * to match any character sequence, ? to match a single character.

Regular Expressions
Employ powerful pattern matching for complex searches.

Fuzzy Search
Find near matches even with typos or slight variations.
Proximity Search
Search for words within a specified distance of each other.

Field Search
Search within specific document fields or properties.

Filtering and Sorting Search Results

Filter by Metadata
Narrow down results based on metadata values.

Filter by Date Range
Limit results to documents within a specific time frame.

Sort by Relevance
Order results based on their relevance to the search query.

Sort by Date
Order results by document creation or modification date.

Custom Sorting
Implement custom sorting logic based on specific criteria.

Working with Metadata

Metadata Extraction
Automatically extract and index metadata during indexing.

Metadata Search
Search and filter results based on extracted metadata.

Metadata Display
Include metadata in search results for additional context.

Highlighting and Snippets

Search Term Highlighting
Visually highlight search terms within the retrieved documents.

Search Result Snippets
Display a short excerpt of text surrounding the search terms to provide context.

Semantic Search and Entity Recognition

Semantic Search
Understand the meaning behind search queries and retrieve conceptually relevant results, going beyond keyword matching.

Entity Recognition
Identify and extract named entities like people, organizations, locations, dates, and more from text.

Sentiment Analysis

Sentiment Determination
Analyze text to determine the overall sentiment expressed, classifying it as positive, negative, or neutral.

Sentiment Scoring
Assign sentiment scores to text, indicating the degree of positivity or negativity.

Document Classification

Text Classification
Categorize documents into predefined classes or categories based on their content.

Custom Classification
Train custom classification models to categorize documents according to specific criteria or taxonomies.

Custom Entity Extraction

Custom Entity Definition
Define custom entity types and extraction rules based on specific requirements.

Custom Entity Extraction
Extract user-defined entities from text using the defined rules and patterns.

Advanced Search API Features

Creating Custom Analyzers
Tailor text processing during indexing and searching. Define tokenization rules, stemming algorithms, stop words, and more.

Configuring Indexing Options
Control which file types and parts of documents are indexed. Set indexing depth and update frequency.

Implementing Search Result Ranking
Customize the scoring algorithm to prioritize certain results. Factor in metadata, document structure, or other custom criteria.

Semantic Search and Entity Recognition
Understand the meaning behind search queries. Identify named entities (people, organizations, locations, etc.) within text.

Sentiment Analysis
Determine the overall sentiment (positive, negative, neutral) expressed in text.

Document Classification
Categorize documents based on their content.

Custom Entity Extraction
Define and extract custom entities from text.

Supported Document Formats

Document Type	Document Type Description	Searchable Data	Supported Versions	Notes
Word Processing
DOC	Microsoft Word® Document	Content and metadata	Microsoft Word® 97+
DOT	Microsoft Word® Document Template	Content and metadata	Microsoft Word® 97+
DOCX	Office Open XML Document	Content and metadata
DOCM	Office Open XML Document [Macro-enabled]	Content and metadata
DOTX	Office Open XML Document Template	Content and metadata
DOTM	Office Open XML Document Template [Macro-enabled]	Content and metadata
TXT	Plain text	Content and metadata
ODT	Open Document Text	Content and metadata
OTT	Open Document Text Template	Content and metadata
RTF	Rich Text Format	Content and metadata	1.9
PDF
PDF	Portable Document Format File	Content and metadata
Markup
HTML	Hypertext Markup Language File	Content and metadata
XHTML	Extensible Hypertext Markup Language File	Content and metadata
MHTML	MIME HTML File	Content and metadata		Not supported by .NET Core version in Linux
MD	Markdown	Content and metadata
XML	XML File	Content and metadata
Ebooks
CHM	Compiled HTML Help File	Content and metadata	1.4
EPUB	Open eBook File	Content and metadata	2.0, 3.0, 3.1
FB2	FictionBook 2.0 File	Content and metadata	2.0
Spreadsheets
XLS	Microsoft Excel® Spreadsheet	Content and metadata	Microsoft Excel® 97+
XLT	Microsoft Excel® Spreadsheet Template	Content and metadata	Microsoft Excel® 97+
XLSX	Office Open XML Spreadsheet	Content and metadata
XLSM	Office Open XML Spreadsheet [Macro-enabled]	Content and metadata
XLSB	Office Open XML Spreadsheet [Binary]	Content and metadata
XLTX	Office Open XML Spreadsheet Template	Content and metadata
XLTM	Office Open XML Spreadsheet Template [Macro-enabled]	Content and metadata
XLA	Microsoft Excel® 97-2003 Add-In	Content and metadata
XLAM	Microsoft Excel® Open XML Add-In	Content and metadata
ODS	Open Document Spreadsheet	Content and metadata
OTS	Open Document Spreadsheet Template	Content and metadata
CSV	Comma Separated Values	Content and metadata
TSV	Tab Separated Values	Content and metadata
XML	SpreadsheetML	Content and metadata
Presentations
PPT	PowerPoint® Presentation	Content and metadata	Microsoft PowerPoint® 97+
PPS	PowerPoint® Slideshow	Content and metadata	Microsoft PowerPoint® 97+
POT	PowerPoint® Template	Content and metadata	Microsoft PowerPoint® 97+
PPTX	Office Open XML Presentation	Content and metadata
PPTM	Office Open XML Presentation [Macro-enabled]	Content and metadata
POTX	Office Open XML Presentation Template	Content and metadata
POTM	Office Open XML Presentation Template [Macro-enabled]	Content and metadata
PPSX	Office Open XML Presentation Slideshow	Content and metadata
PPSM	Office Open XML Presentation Slideshow [Macro-enabled]	Content and metadata
ODP	Open Document Presentation	Content and metadata
Emails
PST	Outlook Personal Information Store File	Content and metadata
OST	Outlook Offline Data File	Content and metadata
EML	E-Mail Message	Content and metadata
EMLX	Apple Mail Message	Content and metadata
MSG	Outlook Mail Message	Content and metadata
Notes
OneNote®	OneNote® Document	Content and metadata	Local files of Microsoft OneNote® 2010-2016	Not supported by .NET Core version in Linux
Archives
ZIP	Zipped File	Content and metadata
Audio
MP3	MPEG-2 Audio Layer III	Metadata only
WAV	Waveform Audio File Format	Metadata only
Images
BMP	Bitmap Picture	Content and metadata
GIF	Graphical Interchange Format File	Content and metadata
JP2	JPEG 2000 Core Image File	Content and metadata
PNG	Portable Network Graphics	Content and metadata
WEBP	WebP Image Format File	Content and metadata
TIFF	Tagged Image File Format	Content and metadata
EMF	Enhanced Windows Metafile	Content and metadata
WMF	Windows Metafile	Content and metadata
JPG	JPEG Image	Content and metadata
PSD	Adobe Photoshop Document	Content and metadata
DJVU	DjVu Image	Content and metadata
Project Management
MPP	Microsoft Project File	Metadata only
Torrents
TORRENT	BitTorrent File	Metadata only
Diagrams
VSD	Visio® Drawing File	Metadata only
VSS	Visio® Stencil File	Metadata only
Medicine
DCM	DICOM Image	Metadata only
DICOM	DICOM Image	Metadata only
Videos
AVI	Audio Video Interleave File	Metadata only
MOV	Apple QuickTime Movie	Metadata only
QT	Apple QuickTime Movie	Metadata only
FLV	Animate Video File	Metadata only
ASF	Advanced Systems Format File	Metadata only

Supported Search Types

Simple word search: Searches for the exact occurrence of a word in the indexed documents.
Boolean search: Combines multiple search terms using logical operators like AND, OR, and NOT.
Regular expression search: Uses patterns and expressions to search for complex text structures.
Faceted search: Filters search results based on specific categories or fields.
Case sensitive search: Differentiates between uppercase and lowercase characters in the search query.
Flexible fuzzy search: Finds words with similar spelling, allowing for minor typing or spelling errors.
Synonym search: Searches for words and their synonyms to expand search results.
Homophone search: Finds words that sound the same but have different spellings.
Wildcard search: Uses placeholders like * or ? to match varying characters or word fragments.
Phrase search with wildcards: Searches for a specific phrase while allowing variations with wildcards.
Search for different word forms: Matches different grammatical forms of a word, such as plural or tense variations.
Date range search: Filters documents based on a specific date or a range of dates.
Numeric range search: Finds data within a specified numeric range.
Search by chunks (pages): Searches within specific sections or pages of a document.
Search for different object types: Searches across various data types, such as text, numbers, dates, file names, and metadata.
Combining different types of search into one search query: Mixes multiple search types, such as combining Boolean and wildcard searches in one query.
Alias substitution in search queries: Replaces defined aliases with their full meanings during the search.
Spell check during search: Automatically corrects minor spelling mistakes in the search query.
Keyboard layout correction during search: Adjusts the search query for different keyboard layouts or language settings.
Search queries in text or flexible object form: Accepts both textual and structured object-based search queries.
Highlighting search results: Highlights the found terms or phrases directly in the document.
Multiple simultaneous thread safe search: Allows multiple searches to be run concurrently without conflicts.
Thread safe search during indexing, updating, or merging operations: Ensures safe searching while the index is being modified.
Search over several indexes simultaneously: Performs searches across multiple indexes in a single operation.
Reverse image search: Finds images based on similarity or matching image characteristics rather than text.

System Requirements

	Supported Platforms/Versions
Supported Operating Systems
Windows	Microsoft Windows 2003 Server (x64, x86), Microsoft Windows 2008 Server (x64, x86), Microsoft Windows 2012 Server (x64, x86), Microsoft Windows 2012 R2 Server (x64, x86), Microsoft Windows 2016 Server (x64, x86), Microsoft Windows 2019 Server (x64, x86), Microsoft Windows Vista (x64, x86), Microsoft Windows XP (x64, x86), Microsoft Windows 7 (x64, x86), Microsoft Windows 8, 8.1 (x64, x86), Microsoft Windows 10 (x64, x86)
Linux	Linux (Ubuntu, OpenSUSE, CentOS, and others)
Supported Frameworks
.NET Frameworks	.NET Framework 4.5, 4.5.1, 4.5.2, 4.6, 4.6.1, 4.6.2, 4.7, 4.7.1, 4.7.2, 4.8, .NET Standard 2.1, .NET Core 3.0, .NET Core 3.1, .NET 5.0, .NET 6.0
Development Environments
Visual Studio Versions	Microsoft Visual Studio 2012, 2013, 2015, 2017, 2019, 2022

Install via NuGet

Using Package Manager GUI

Open your solution in Visual Studio.
Go to Tools → NuGet Package Manager → Manage NuGet Packages for Solution.
In the Browse tab, search for GroupDocs.Search.
Click Install to add it to your project.

Using Package Manager Console

Open your solution in Visual Studio.
Go to Tools → NuGet Package Manager → Package Manager Console.
Run the command:
```
Install-Package GroupDocs.Search
```
GroupDocs.Search will be referenced in your project.

Install from Official Website

Download and unpack the ZIP or use the MSI installer from the official website.
In Visual Studio, right-click References and select Add Reference.
Browse and select GroupDocs.Search.dll, or choose from the installed components.
Click OK to complete the reference.

Indexing Documents from URL Using GroupDocs.Search for .NET

Learn how to index a document from a URL using GroupDocs.Search for .NET. This example demonstrates lazy initialization of documents from a URL and indexing them for efficient search in .NET applications.

    // Class to load a document from a URL with lazy initialization
    private class DocumentLoaderFromUrl : IDocumentLoader
    {
        private readonly string documentKey; // Document identifier (URL in this case)
        private readonly string url; // The URL to fetch the document from
        private readonly string extension; // The file extension of the document
        
        // Constructor to initialize document properties
        public DocumentLoaderFromUrl(string documentKey, string url, string extension)
        {
            this.documentKey = documentKey;
            this.url = url;
            this.extension = extension;
        }

        // Method to load the document from the URL stream
        public Document LoadDocument()
        {
            // Configure security protocols for web requests
            ServicePointManager.Expect100Continue = true;
            ServicePointManager.SecurityProtocol =
                SecurityProtocolType.Ssl3 |
                SecurityProtocolType.Tls |
                SecurityProtocolType.Tls12 |
                SecurityProtocolType.Tls11;

            // Create a web request to access the URL
            WebRequest request = WebRequest.Create(url);
            using (WebResponse response = request.GetResponse())
            using (Stream stream = response.GetResponseStream())
            {
                // Copy the stream into memory
                MemoryStream memoryStream = new MemoryStream();
                stream.CopyTo(memoryStream);
                memoryStream.Position = 0;

                // Create a Document object from the memory stream
                Document document = Document.CreateFromStream(documentKey, DateTime.Now, extension, memoryStream);
                return document;
            }
        }

        // Method to close the document (empty in this case)
        public void CloseDocument()
        {
        }
    }

        // Define the index folder path where the index will be stored
        string indexFolder = @"c:\MyIndex";

        // Define the URL of the document to be indexed
        string url = "http://example.com/ExampleDocument.pdf";

        // Creating an index in the specified folder
        Index index = new Index(indexFolder);

        // Creating a document loader object to fetch the document from the URL
        string documentKey = url;
        IDocumentLoader documentLoader = new DocumentLoaderFromUrl(documentKey, url, ".pdf");

        // Creating a lazy-initialized document object
        Document document = Document.CreateLazy(DocumentSourceKind.Stream, documentKey, documentLoader);

        // Prepare an array of documents for indexing
        Document[] documents = new Document[] { document };

        // Indexing options (default options in this case)
        IndexingOptions options = new IndexingOptions();

        // Add the lazy-loaded document to the index
        index.Add(documents, options);

Source*

Homophone Search Using GroupDocs.Search for .NET

Learn how to perform homophone search using GroupDocs.Search for .NET. This code example demonstrates enabling homophone search to find similar-sounding words like “coal,” “cole,” and “kohl” in indexed documents.

// Specify the index folder path where the index will be created
string indexFolder = @"c:\MyIndex\";

// Specify the folder path containing documents to be indexed
string documentsFolder = @"c:\MyDocuments\";

// Creating an index in the specified folder
Index index = new Index(indexFolder);

// Adding documents to the index from the specified folder
index.Add(documentsFolder);

// Creating search options to enable homophone search
SearchOptions options = new SearchOptions();
options.UseHomophoneSearch = true; // Enabling homophone search

// Search for the word 'coal' in the indexed documents
// Homophone search will also find words that sound like 'coal', such as 'cole' and 'kohl'
SearchResult result = index.Search("coal", options);

Source*

Perform Shard Optimization using GroupDocs.Search for .NET

Learn how to optimize shards in a search network using GroupDocs.Search for .NET. This example demonstrates how to improve search performance by minimizing the number of index segments on each shard through the optimization process.

// Inform the user that the optimization process is starting
Console.WriteLine("Optimizing shards");

// Access the Indexer class for the current search network node
Indexer indexer = node.Indexer; // Assuming 'node' is defined elsewhere in your search network

// Create optimization options
OptimizeOptions options = new OptimizeOptions();

// Perform the optimization process on all shards
indexer.Optimize(options); // This reduces the number of index segments on each shard

Source*

GroupDocs.Search GroupDocs.Total Conholdate Conholdate.Total Document-Automation API Component Library VisualStudio C# CSharp Windows Linux .NETFramework Framework .NETCore DOC DOT DOCX DOCM DOTX DOTM TXT ODT OTT RTF PDF Markup HTML XHTML MHTML MD XML Ebook CHM EPUB FB2 Spreadsheet XLS XLT XLSX XLSM XLSB XLTX XLTM XLA XLAM ODS OTS CSV TSV XML Presentation PPT PPS POT PPTX PPTM POTX POTM PPSX PPSM ODP Email PST OST EML EMLX MSG Note ONE ONENOTE Archive ZIP Audio MP3 WAV Image BMP GIFJP2 PNG WEBP TIFF EMF WMF JPG PSD DJVU Project Management MPP TORRENT Diagram VSD VSS Medical-Imaging DCM DICOM Video AVI MOV QT FLV ASF Automation Full-Text-Search Indexing Search Word-Search Boolean Regular-Expression RegEx Faceted Case-Sensitive Fuzzy Synonym Homophone Wildcard Phrase Date Range Numeric Chunk Page Filter Filtering Alias Spell-Check Spell Keyboard Layout Query Thread-Safe-Search Indexes Word Excel PowerPoint Project Diagram OneNote Document Spreadsheet Presentation OpenDocument Email Web Homophonic CaseSensitive Phrase Outlook Morphologic

Direct Download

GroupDocs.Search for .NET 26.8

This contains the MSI installer of GroupDocs.Search for .NET 26.8 release.

Added: 5/8/2026 Downloads: