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

Screenshot, showing a sample diff


Simply install kitty. You also need to have either the git program or the diff program installed. Additionally, for syntax highlighting to work, pygments must be installed (note that pygments is included in the macOS kitty app).


In the kitty terminal, run:

kitty +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="kitty +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




q, Ctrl+c, Esc

Scroll line up

k, up

Scroll line down

j, down

Scroll page up


Scroll page down


Scroll to top


Scroll to bottom


Scroll to next page

Space, PgDn

Scroll to previous page


Scroll to next change


Scroll to previous change


Increase lines of context


Decrease lines of context


All lines of context


Restore default context


Search forwards


Search backwards


Clear search


Scroll to next match

>, .

Scroll to previous match

<, ,

Integrating with git

Add the following to ~/.gitconfig:

    tool = kitty
    guitool = kitty.gui
    prompt = false
    trustExitCode = true
[difftool "kitty"]
    cmd = kitty +kitten diff $LOCAL $REMOTE
[difftool "kitty.gui"]
    cmd = kitty kitty +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 2000 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 :)


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.


syntax_aliases pyj:py pyi:py recipe:py

File extension aliases for syntax highlight For example, to syntax highlight as use a setting of xyz:abc

num_context_lines 3

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

diff_cmd auto

The diff command to use. Must contain the placeholder _CONTEXT_ which will be replaced by the number of lines of context. The default is to search the system for either git or diff and use that, if found.

replace_tab_by \x20\x20\x20\x20

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


pygments_style default

The pygments color scheme to use for syntax highlighting. See pygments colors schemes for a list of schemes.

foreground, background
foreground black
background white

Basic colors

title_fg, title_bg
title_fg black
title_bg white

Title colors

margin_bg, margin_fg
margin_bg #fafbfc
margin_fg #aaaaaa

Margin colors

removed_bg, highlight_removed_bg, removed_margin_bg
removed_bg           #ffeef0
highlight_removed_bg #fdb8c0
removed_margin_bg    #ffdce0

Removed text backgrounds

added_bg, highlight_added_bg, added_margin_bg
added_bg           #e6ffed
highlight_added_bg #acf2bd
added_margin_bg    #cdffd8

Added text backgrounds

filler_bg #fafbfc

Filler (empty) line background

margin_filler_bg none

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

hunk_margin_bg, hunk_bg
hunk_margin_bg #dbedff
hunk_bg        #f1f8ff

Hunk header colors

search_bg, search_fg, select_bg, select_fg
search_bg #444
search_fg white
select_bg #b4d5fe
select_fg black


Keyboard shortcuts

map q quit
map esc quit
Scroll down
map j scroll_by 1
map down scroll_by 1
Scroll up
map 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
Scroll to previous page
map page_up scroll_to prev-page
Scroll to next change
map n scroll_to next-change
Scroll to previous change
map p scroll_to prev-change
Show all context
map 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 f start_search substring forward
Search backward (no regex)
map b start_search substring backward

Source code for diff

The source code for this kitten is available on GitHub.

Command Line Interface

kitty +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.


--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 a 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.

--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.