FastColoredTextBox

Fast Colored TextBox is text editor component for .NET. Allows you to create custom text editor with syntax highlighting. It works well with small, medium, large and very-very large files.

It has such settings as foreground color, font style, background color which can be adjusted for arbitrarily selected text symbols. One can easily gain access to a text with the use of regular expressions. WordWrap, Find/Replace, Code folding and multilevel Undo/Redo are supported as well.

中文文档

Update Logs

29-09-2026 (V2.18.0.220)

• TextBox migration: the public properties a WinForms form needs but FCTB lacked are now implemented, so a TextBox can be replaced by a FastColoredTextBox without touching the call site: MaxLength, CharacterCasing, CanUndo, Modified, HideSelection, PasswordChar, UseSystemPasswordChar, PlaceholderText, PreferredHeight, ScrollBars, ShortcutsEnabled, TextAlign, AutoCompleteMode, AutoCompleteSource, AutoCompleteCustomSource
• Lines now returns string[] and has a setter, matching TextBoxBase.Lines
• Removed the new bool RightToLeft shadow that threw NotImplementedException; the inherited Control.RightToLeft is used again
• ForceUpperCase is now a shorthand for CharacterCasing = Upper

See Migrating from TextBox below.

07-09-2026 (V2.17.0.206)

• Horizontal scroll text overlapping line number area fully fixed (CJK line re-evaluation, non-uniform char width support)

04-09-2025 (V2.17.0.205)

• Undo/Redo core logic refactored (position accuracy, cross-line support)
• Column selection mode IndexOutOfRangeException fixed
• Horizontal scroll text overlapping line numbers fixed
• Default padding 2px (matches WinForms TextBox)
• Localization support for Find/Replace/GoTo/Hotkeys forms (EN/ZH)
• Chinese labels shortened to match English width
• Label z-order fixed (no longer overlaps controls)
• Redo shortcut changed to Ctrl+Y (standard Windows convention)
• .NET 10.0 support added

25-12-22 (V2.17.0.203)

• A wordwrapping bug fixed
• .NET6.0 target removed for better code optimization (now targeting .NET7-9)
• Some other code optimization

25-04-02 (V2.17.0.2)

• CJKL mix wordwrapping almost perfect/中日韩拉丁字母混合换行基本完美
• Targeting .NET6.0-9.0
• Restructed the code and minor optimization

24-12-30 (V2.17.0.0)

• Reforked from Wiredwizard:-Daxanius:-PavelTorgashov 24-12-25 (V2.16.27.106)
• Improved CJK support with demo added,now it suits general CJK application comfortably.
• CN:添加了CJK支持，做了demo，现在支持一般CJK应用没问题。 24-12-24 (V2.16.27.103)
• Add UseCJK property, may need further improvements.

24-12-20 (V2.16.27.100)

• Start to support correct displaying Chinese based on the lately found fork by Daxanius, though not perfect, still needs some tweeks in later version
• CN:在能找到的最新的Daxanius版本上增加了汉字显示支持，虽不完美还需在以后版本调整
• Multitargeting net6.0-8.0
• Upgrade to C#12 sematics

Migrating from TextBox

Every public instance property of System.Windows.Forms.TextBox exists on FastColoredTextBox with the same type and the same public accessors, so dropping one control in place of the other compiles. The members that had to be added, and how far they go:

Member	Behaviour
MaxLength	Limits typing, like TextBoxBase. Assigning Text/SelectedText is not truncated (same as TextBox). Negative values throw.
CharacterCasing	Applied to every char that enters the control, typed or inserted. ForceUpperCase is a shorthand for CharacterCasing = Upper.
CanUndo	true while there is something to undo.
Modified	Mirrors IsChanged; settable.
HideSelection	Hides the selection while the control is unfocused (default true).
PasswordChar / UseSystemPasswordChar	Masks the rendered glyphs. The text itself, the clipboard and the exporters are untouched.
PlaceholderText	Drawn while the control is empty.
PreferredHeight	Height of one text line.
ScrollBars	None/Both map onto ShowScrollBars. Vertical/Horizontal behave as Both: the scrollbars are driven by ScrollableControl.AutoScroll and cannot be shown one axis at a time.
ShortcutsEnabled	false suppresses the hotkeys of HotkeysMapping; typing is unaffected.
TextAlign	Offsets a single-line control's text. Ignored while Multiline or WordWrap is set.
AutoCompleteMode / AutoCompleteSource / AutoCompleteCustomSource	Append and SuggestAppend append the missing tail when a delimiter is typed (SuggestAppend leaves it selected). Single-line only, like TextBox. The inline ghost hint of Suggest is not drawn - use AutocompleteMenu for that.

Still not carried over (used far less often, add them if you need them): DeselectAll, Paste(string), GetCharFromPosition, GetCharIndexFromPosition, GetPositionFromCharIndex, GetLineFromCharIndex, GetFirstCharIndexFromLine, GetFirstCharIndexOfCurrentLine, and the *Changed events for ReadOnly, Multiline, AcceptsTab, BorderStyle, HideSelection, Modified and TextAlign.

Two signatures deliberately differ from TextBox because FCTB's own API depends on them: TextChanged carries TextChangedEventArgs rather than EventArgs, and right-to-left text is not rendered (RightToLeft is accepted but ignored).

Known Issues

• Wordwrapped lines may exceed controlwidth in some cases, but can be solved by setting PaddingRight property.

More details http://www.codeproject.com/Articles/161871/Fast-Colored-TextBox-for-syntax-highlighting

Nuget package https://www.nuget.org/packages/VAX-FCTB/