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.

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Features

• Fast: Up to 400x faster than RichTextBox — and over 100x faster at minimum
• Accurate: All characters converted correctly — even Wingdings
• Fully cross-platform
• Can read from forward-only streams such as DeflateStream

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Installation

Install the library via NuGet:

dotnet add package ReasonableRTF.Standard

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Quick Start

Converting An RTF File

Use the static ConvertRtf.ToText() method to do a one-off conversion:

using ReasonableRTF;
using ReasonableRTF.Enums;
using ReasonableRTF.Models;

// ...

RtfResult result = ConvertRtf.ToText(@"C:\rtf_files\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}");
    }
}

Converting Many RTF Files Efficiently

You can create and reuse an RtfToTextConverter instance to minimize overhead when converting many files:

using ReasonableRTF;
using ReasonableRTF.Enums;
using ReasonableRTF.Models;

// ...

RtfToTextConverter converter = new RtfToTextConverter();
foreach (string fileName in Directory.EnumerateFiles(@"C:\rtf_files\", "*.rtf"))
{
    RtfResult result = converter.Convert(fileName);
    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}");
        }
    }
}

For efficiency, an RtfToTextConverter will not trim its internal growable buffers between conversions. You can use the ResetMemory() method to reset these buffers back to their default sizes. This way, you can keep one RtfToTextConverter instance around indefinitely without worrying about memory use.

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The RtfResult Struct

The RtfResult struct 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.

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Conversion Options

For more control over the output, you can provide an instance of the RtfToTextConverterOptions class.

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

RtfResult result = ConvertRtf.ToText(@"C:\rtf_files\some_file.rtf", options);
// ... check result

The available options are documented in RtfToTextConverterOptions.cs.

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Benchmarks

.NET 10 64-bit

BenchmarkDotNet v0.15.8, Windows 11 (10.0.26200.9168/25H2/2025Update/HudsonValley2)
AMD Ryzen 5 5600 3.50GHz, 1 CPU, 12 logical and 6 physical cores
.NET SDK 10.0.400
  [Host]     : .NET 10.0.11 (10.0.11, 10.0.1126.37416), X64 RyuJIT x86-64-v3
  DefaultJob : .NET 10.0.11 (10.0.11, 10.0.1126.37416), 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	15.324 ms	0.0298 ms	0.0279 ms	9476.10 MB/s	217x
ReasonableRTF_NoImageSet	3.456 ms	0.0099 ms	0.0093 ms	1025.37 MB/s	414x
ReasonableRTF_FullSet_Streamed	17.187 ms	0.0608 ms	0.0568 ms	8448.93 MB/s	194x
ReasonableRTF_NoImageSet_Streamed	3.483 ms	0.0082 ms	0.0077 ms	1017.42 MB/s	411x

.NET Framework 4.8 64-bit

BenchmarkDotNet v0.15.8, Windows 11 (10.0.26200.9168/25H2/2025Update/HudsonValley2)
AMD Ryzen 5 5600 3.50GHz, 1 CPU, 12 logical and 6 physical cores
  [Host]     : .NET Framework 4.8.1 (4.8.9337.0), X64 RyuJIT VectorSize=256
  DefaultJob : .NET Framework 4.8.1 (4.8.9337.0), X64 RyuJIT VectorSize=256

Method	Mean	Error	StdDev	Speed
RichTextBox_FullSet	2,779.775 ms	3.9318 ms	3.2833 ms	52.24 MB/s	1x
RichTextBox_NoImageSet	992.237 ms	2.5478 ms	2.2585 ms	3.57 MB/s	1x
ReasonableRTF_FullSet	19.267 ms	0.0557 ms	0.0521 ms	7536.81 MB/s	144x
ReasonableRTF_NoImageSet	4.616 ms	0.0137 ms	0.0128 ms	767.69 MB/s	215x
ReasonableRTF_FullSet_Streamed	21.807 ms	0.0713 ms	0.0667 ms	6658.95 MB/s	127x
ReasonableRTF_NoImageSet_Streamed	4.772 ms	0.0074 ms	0.0066 ms	742.60 MB/s	208x

.NET Framework 4.8 32-bit

BenchmarkDotNet v0.15.8, Windows 11 (10.0.26200.9168/25H2/2025Update/HudsonValley2)
AMD Ryzen 5 5600 3.50GHz, 1 CPU, 12 logical and 6 physical cores
  [Host]     : .NET Framework 4.8.1 (4.8.9337.0), X86 LegacyJIT
  DefaultJob : .NET Framework 4.8.1 (4.8.9337.0), X86 LegacyJIT

Method	Mean	Error	StdDev	Speed
RichTextBox_FullSet	6,932.056 ms	131.6848 ms	140.9013 ms	20.95 MB/s	1x
RichTextBox_NoImageSet	2,885.139 ms	57.0121 ms	81.7651 ms	1.23 MB/s	1x
ReasonableRTF_FullSet	41.775 ms	0.1700 ms	0.1590 ms	3476.04 MB/s	166x
ReasonableRTF_NoImageSet	8.043 ms	0.0225 ms	0.0200 ms	440.59 MB/s	359x
ReasonableRTF_FullSet_Streamed	46.175 ms	0.0486 ms	0.0431 ms	3144.81 MB/s	150x
ReasonableRTF_NoImageSet_Streamed	8.122 ms	0.0196 ms	0.0183 ms	436.30 MB/s	355x

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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

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

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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 ported the original .NET-only version to .NET Standard.