ReasonableRTF - Fast RTF to Plain Text Converter 🚀

A lightweight and performant C# library designed for rapidly converting Rich Text Format (RTF) files into plain text.

---

Features

• Fast: Over 100x faster than RichTextBox.
• Accurate: All characters converted correctly — even Wingdings.
• Small: Less than 50k.
• Fully cross-platform.
• Can read from forward-only streams such as DeflateStream.
• We even support this obscure nonsense.

---

Installation

Install the library via NuGet:

dotnet add package ReasonableRTF.Standard

---

Quick Start

Converting an RTF file to plain text is straightforward. The Convert method returns an RtfResult object, providing the converted text and comprehensive error information, if any.

Basic Conversion

Here is how to convert an RTF file to a plain text string:

using ReasonableRTF;
using ReasonableRTF.Models;
using System.IO;

// ...

// 1. Initialize the converter
RtfToTextConverter converter = new RtfToTextConverter();

// 2. Load the RTF data from a file and convert
RtfResult result = converter.Convert("some_file.rtf");

if (result.Error == RtfError.OK)
{
    // Conversion was successful
    string plainText = result.Text;
    Console.WriteLine("Converted Text:\n" + plainText);
}
else
{
    // Handle conversion errors
    Console.WriteLine($"Conversion Error: {result.Error} at byte position: {result.BytePositionOfError}");
    if (result.Exception != null)
    {
        Console.WriteLine($"Exception Details: {result.Exception.Message}");
    }
}

---

The RtfResult Class

The RtfResult object provides full details about the conversion process, ensuring you can robustly handle success and failure cases.

Property	Type	Description
Text	string	The converted plain text.
Error	RtfError	The error code. This will be RtfError.OK upon successful conversion.
BytePositionOfError	int	The approximate position in the data stream where the error occurred, or -1 if no error.
Exception	Exception?	The caught exception, or null if no exception occurred during conversion.

---

Conversion Options

For more control over the output, you can provide an instance of the RtfToTextConverterOptions class to the Convert method. This allows customization of line breaks, special character handling, and hidden text inclusion.

Applying Options

RtfToTextConverter converter = new RtfToTextConverter();
RtfToTextConverterOptions options = new RtfToTextConverterOptions
{
    ConvertHiddenText = true, // Include text marked as hidden
    LineBreakStyle = LineBreakStyle.LF // Use Unix-style line breaks
};

RtfResult result = converter.Convert("some_file.rtf", options);
// ... check result

RtfToTextConverterOptions Properties

Property	Type	Default	Description
SwapUppercaseAndLowercasePhiSymbols	bool	true	If set to true, swaps the uppercase and lowercase Greek phi characters in the Symbol font translation. This addresses a common reversal in the Windows Symbol font.
SymbolFontA0Char	SymbolFontA0Char	SymbolFontA0Char.EuroSign	Sets the character at index 0xA0 (160) in the Symbol font to Unicode translation table. Important for compatibility with older Symbol font versions.
LineBreakStyle	LineBreakStyle	LineBreakStyle.EnvironmentDefault	Specifies the line break style (CRLF, LF, or environment default) for the converted plain text output.
ConvertHiddenText	bool	false	Determines whether text marked as hidden in the RTF file should be included in the plain text output.

---

Benchmarks

BenchmarkDotNet v0.15.8, Windows 11 (10.0.26200.8039/25H2/2025Update/HudsonValley2)
AMD Ryzen 5 5600 3.50GHz, 1 CPU, 12 logical and 6 physical cores
.NET SDK 10.0.201
  [Host]     : .NET 10.0.5 (10.0.5, 10.0.526.15411), X64 RyuJIT x86-64-v3
  DefaultJob : .NET 10.0.5 (10.0.5, 10.0.526.15411), X64 RyuJIT x86-64-v3

Method	Mean	Error	StdDev	Speed
RichTextBox_FullSet	3,331.340 ms	6.2250 ms	5.5183 ms	43.59 MB/s	1x
RichTextBox_NoImageSet	1,432.217 ms	3.7089 ms	3.4693 ms	2.47 MB/s	1x
ReasonableRTF_FullSet	28.683 ms	0.0617 ms	0.0577 ms	5062.64 MB/s	116x
ReasonableRTF_NoImageSet	7.744 ms	0.0153 ms	0.0143 ms	457.60 MB/s	185x
ReasonableRTF_FullSet_Streamed	30.534 ms	0.0320 ms	0.0300 ms	4755.74 MB/s	109x
ReasonableRTF_NoImageSet_Streamed	7.824 ms	0.0229 ms	0.0214 ms	452.92 MB/s	183x

---

Supported RTF features

Supported

• All basic plain text, hex-encoded chars, Unicode-encoded chars
• Symbol fonts (Wingdings 1, 2 and 3, Webdings, Symbol, and Zapf Dingbats) converted to Unicode equivalents
• Characters specified as "SYMBOL" field instructions
• Undocumented use of the \langN keyword to specify character encoding - old versions of RichTextBox used to support this

Partially supported

• Tables: Cells and rows have spaces between them, but not much functionality beyond that.
• Lists: Numbers and bullets show up (that's better than RichTextBox most of the time), but indentation usually doesn't.

Not currently supported

• Footnotes
• "HYPERLINK" field instruction value
• Math objects

---

License and Attribution

Code License

The original code for this RTF converter was written by Brian Tobin and is licensed under the MIT License (Copyright 2024-2026 Brian Tobin). For the full license text, please refer to the LICENSE file ReasonableRTF.

Flamifly contributed to the readme (installation, quick start, documentation, etc), and created the .NET Standard version.