Name

kitten-diff - Pretty, side-by-side diffing of files and images

A fast side-by-side diff tool with syntax highlighting and images

Major features

Displays diffs side-by-side in the kitty terminal
Does syntax highlighting of the displayed diffs, asynchronously, for maximum speed
Displays images as well as text diffs, even over SSH
Does recursive directory diffing

Screenshot, showing a sample diff (images not supported)

Installation

Simply install kitty.

Usage

In the kitty terminal, run:

kitten diff file1 file2

to see the diff between file1 and file2.

Create an alias in your shell's startup file to shorten the command, for example:

alias d="kitten diff"

Now all you need to do to diff two files is:

d file1 file2

You can also pass directories instead of files to see the recursive diff of the directory contents.

Keyboard controls

Action	Shortcut
Quit	Q
Scroll line up	K, Up
Scroll line down	J, Down
Scroll page up	PgUp
Scroll page down	PgDn
Scroll to top	Home
Scroll to bottom	End
Scroll to next page	Space, PgDn, Ctrl+F
Scroll to previous page	PgUp, Ctrl+B
Scroll down half page	Ctrl+D
Scroll up half page	Ctrl+U
Scroll to next change	N
Scroll to previous change	P
Increase lines of context	+
Decrease lines of context	-
All lines of context	A
Restore default context	=
Search forwards	/
Search backwards	?
Clear search or exit	Esc
Scroll to next match	>, .
Scroll to previous match	<, ,
Copy selection to clipboard	y
Copy selection or exit	Ctrl+C

Integrating with git

Add the following to ~/.gitconfig:

[diff]


    tool = kitty


    guitool = kitty.gui
[difftool]


    prompt = false


    trustExitCode = true
[difftool "kitty"]


    cmd = kitten diff $LOCAL $REMOTE
[difftool "kitty.gui"]


    cmd = kitten diff $LOCAL $REMOTE

Now to use kitty-diff to view git diffs, you can simply do:

git difftool --no-symlinks --dir-diff

Once again, creating an alias for this command is useful.

Why does this work only in kitty?

The diff kitten makes use of various features that are kitty only, such as the kitty graphics protocol, the extended keyboard protocol, etc. It also leverages terminal program infrastructure I created for all of kitty's other kittens to reduce the amount of code needed (the entire implementation is under 3000 lines of code).

And fundamentally, it's kitty only because I wrote it for myself, and I am highly unlikely to use any other terminals :)

Configuration

You can configure the colors used, keyboard shortcuts, the diff implementation, the default lines of context, etc. by creating a diff.conf file in your kitty config folder. See below for the supported configuration directives.

Diffing

syntax_aliases

syntax_aliases pyj:py pyi:py recipe:py

File extension aliases for syntax highlight. For example, to syntax highlight file.xyz as file.abc use a setting of xyz:abc. Multiple aliases must be separated by spaces.

num_context_lines

num_context_lines 3

The number of lines of context to show around each change.

diff_cmd

diff_cmd auto

The diff command to use. Must contain the placeholder _CONTEXT_ which will be replaced by the number of lines of context. A few special values are allowed: auto will automatically pick an available diff implementation. builtin will use the anchored diff algorithm from the Go standard library. git will use the git command to do the diffing. diff will use the diff command to do the diffing.

replace_tab_by

replace_tab_by \x20\x20\x20\x20

The string to replace tabs with. Default is to use four spaces.

ignore_name

A glob pattern that is matched against only the filename of files and directories. Matching files and directories are ignored when scanning the filesystem to look for files to diff. Can be specified multiple times to use multiple patterns. For example:

ignore_name .git
ignore_name *~
ignore_name *.pyc

mark_moved_lines

mark_moved_lines yes

Highlight lines that are moved, that is removed from the left and added to the right differently, using the moved_bg color.

word_diff_mode

word_diff_mode words

The algorithm to use for highlighting which parts of changed lines differ. When set to words, changed words in each changed line are highlighted. When set to central, the central changed region of each changed line is highlighted at the byte level. The words mode is generally more useful as it shows exactly which words changed. Note that the words mode only applies when a changed chunk has equal numbers of added and removed lines.

word_regex

word_regex [^\s\p{P}]+

The regular expression used to define a word when word_diff_mode is words. The default value matches any run of non-whitespace and non-punctuation characters. The expression must be a valid Go regular expression. If an invalid expression is provided, diff will fail with an error.

sticky_header

sticky_header yes

When scrolled past the header of a file, keep the file's name and separator pinned to the top of the screen.

Colors

color_scheme

color_scheme auto

Whether to use the light or dark colors. The default of auto means to follow the parent terminal color scheme. Note that the actual colors used for dark schemes are set by the dark_* settings below and the non-prefixed settings are used for light colors.

pygments_style

pygments_style default

The pygments color scheme to use for syntax highlighting. See pygments builtin styles for a list of schemes. Note that this does not change the colors used for diffing, only the colors used for syntax highlighting. To change the general colors use the settings below. This sets the colors used for light color schemes, use dark_pygments_style to change the colors for dark color schemes.

dark_pygments_style

dark_pygments_style github-dark

The pygments color scheme to use for syntax highlighting with dark colors. See pygments builtin styles for a list of schemes. Note that this does not change the colors used for diffing, only the colors used for syntax highlighting. To change the general colors use the settings below. This sets the colors used for dark color schemes, use pygments_style to change the colors for light color schemes.

foreground, dark_foreground, background, dark_background

foreground      black
dark_foreground #f8f8f2
background      white
dark_background #212830

Basic colors

title_fg, dark_title_fg, title_bg, dark_title_bg

title_fg      black
dark_title_fg white
title_bg      white
dark_title_bg #212830

Title colors

margin_bg, dark_margin_bg, margin_fg, dark_margin_fg

margin_bg      #fafbfc
dark_margin_bg #212830
margin_fg      #aaaaaa
dark_margin_fg #aaaaaa

Margin colors

removed_bg, dark_removed_bg, highlight_removed_bg, dark_highlight_removed_bg, removed_margin_bg, dark_removed_margin_bg

removed_bg                #ffeef0
dark_removed_bg           #352c33
highlight_removed_bg      #fdb8c0
dark_highlight_removed_bg #5c3539
removed_margin_bg         #ffdce0
dark_removed_margin_bg    #5c3539

Removed text backgrounds

added_bg, dark_added_bg, highlight_added_bg, dark_highlight_added_bg, added_margin_bg, dark_added_margin_bg

added_bg                #e6ffed
dark_added_bg           #263834
highlight_added_bg      #acf2bd
dark_highlight_added_bg #31503d
added_margin_bg         #cdffd8
dark_added_margin_bg    #31503d

Added text backgrounds

moved_bg, dark_moved_bg, moved_margin_bg, dark_moved_margin_bg

moved_bg             #fffde7
dark_moved_bg        #003333
moved_margin_bg      #fff3b0
dark_moved_margin_bg #00495b

Moved text backgrounds (same text that was removed in one place and added in another)

filler_bg, dark_filler_bg

filler_bg      #fafbfc
dark_filler_bg #262c36

Filler (empty) line background

margin_filler_bg, dark_margin_filler_bg

margin_filler_bg      none
dark_margin_filler_bg none

Filler (empty) line background in margins, defaults to the filler background

hunk_margin_bg, dark_hunk_margin_bg, hunk_bg, dark_hunk_bg

hunk_margin_bg      #dbedff
dark_hunk_margin_bg #0c2d6b
hunk_bg             #f1f8ff
dark_hunk_bg        #253142

Hunk header colors

search_bg, dark_search_bg, search_fg, dark_search_fg, select_bg, dark_select_bg, select_fg, dark_select_fg

search_bg      #444
dark_search_bg #2c599c
search_fg      white
dark_search_fg white
select_bg      #b4d5fe
dark_select_bg #2c599c
select_fg      black
dark_select_fg white

Highlighting

Keyboard shortcuts

Quit

map --allow-fallback=shifted,ascii q quit
map esc quit

Scroll down

map --allow-fallback=shifted,ascii j scroll_by 1
map down scroll_by 1

Scroll up

map --allow-fallback=shifted,ascii k scroll_by -1
map up scroll_by -1

Scroll to top

map home scroll_to start

Scroll to bottom

map end scroll_to end

Scroll to next page

map page_down scroll_to next-page
map space scroll_to next-page
map --allow-fallback=shifted,ascii ctrl+f scroll_to next-page

Scroll to previous page

map page_up scroll_to prev-page
map --allow-fallback=shifted,ascii ctrl+b scroll_to prev-page

Scroll down half page

map --allow-fallback=shifted,ascii ctrl+d scroll_to next-half-page

Scroll up half page

map --allow-fallback=shifted,ascii ctrl+u scroll_to prev-half-page

Scroll to next change

map --allow-fallback=shifted,ascii n scroll_to next-change

Scroll to previous change

map --allow-fallback=shifted,ascii p scroll_to prev-change

Scroll to next file

map --allow-fallback=shifted,ascii shift+j scroll_to next-file

Scroll to previous file

map --allow-fallback=shifted,ascii shift+k scroll_to prev-file

Show all context

map --allow-fallback=shifted,ascii a change_context all

Show default context

map = change_context default

Increase context

map + change_context 5

Decrease context

map - change_context -5

Search forward

map / start_search regex forward

Search backward

map ? start_search regex backward

Scroll to next search match

map . scroll_to next-match
map > scroll_to next-match

Scroll to previous search match

map , scroll_to prev-match
map < scroll_to prev-match

Search forward (no regex)

map --allow-fallback=shifted,ascii f start_search substring forward

Search backward (no regex)

map --allow-fallback=shifted,ascii b start_search substring backward

Copy selection to clipboard

map --allow-fallback=shifted,ascii y copy_to_clipboard

Copy selection to clipboard or exit if no selection is present

map --allow-fallback=shifted,ascii ctrl+c copy_to_clipboard_or_exit

Source code for diff

The source code for this kitten is available on GitHub.

Command line interface

kitten diff [options] file_or_directory_left file_or_directory_right

Show a side-by-side diff of the specified files/directories. You can also use ssh:hostname:remote-file-path to diff remote files.

Options

--context <CONTEXT>: Number of lines of context to show between changes. Negative values use the number set in diff.conf. Default: -1

--config <CONFIG>

Specify a path to the configuration file(s) to use. All configuration files are merged onto the builtin diff.conf, overriding the builtin values. This option can be specified multiple times to read multiple configuration files in sequence, which are merged. Use the special value NONE to not load any config file.

If this option is not specified, config files are searched for in the order: $XDG_CONFIG_HOME/kitty/diff.conf, ~/.config/kitty/diff.conf, $XDG_CONFIG_DIRS/kitty/diff.conf. The first one that exists is used as the config file.

If the environment variable KITTY_CONFIG_DIRECTORY is specified, that directory is always used and the above searching does not happen.

If /etc/xdg/kitty/diff.conf exists, it is merged before (i.e. with lower priority) than any user config files. It can be used to specify system-wide defaults for all users. You can use either - or /dev/stdin to read the config from STDIN.

--override <OVERRIDE>, -o <OVERRIDE>: Override individual configuration options, can be specified multiple times. Syntax: name=value. For example: -o background=gray

Sample diff.conf

You can download a sample diff.conf file with all default settings and comments describing each setting by clicking: sample diff.conf.

Author

Kovid Goyal

Copyright

2026, Kovid Goyal

kitten-diff(1)