Keybindings

nless uses vi-like keybindings. Press ? inside the app to view this reference.

Buffers

Key	Action
1–9	Select the buffer at the corresponding index
L	Select the next buffer
H	Select the previous buffer
q	Close the current active buffer, or quit if all buffers are closed. When stdout is a pipe, the current buffer is auto-written to stdout on quit.
Q	Quit immediately — exit without closing tabs one-by-one. In pipe mode, pipes the current buffer to stdout.
N	Create a new buffer from the original data
r	Rename the current buffer
M	Merge the current buffer with another buffer — creates a new tab with interleaved rows and a _source column

Groups

Key	Action
}	Switch to the next buffer group
{	Switch to the previous buffer group
R	Rename the current group
O	Open a file in a new buffer group

Tip: You can also pass multiple files from the command line — nless file1.csv file2.csv opens each as a separate group.

Navigation

Key	Action
h	Move cursor left
l	Move cursor right
j	Move cursor down
k	Move cursor up
0	Jump to first column
$	Jump to final column
g	Jump to first row
G	Jump to final row
w	Move cursor right
b / B	Move cursor left
ctrl+u	Page up
ctrl+d	Page down
c	Select a column to jump the cursor to

Column Visibility

Key	Action
C	Prompt for a regex filter to selectively display columns, or all to see all columns
m	Pin or unpin the current column to the left side of the screen — pinned columns stay visible during horizontal scrolling
>	Move the current column one to the right
<	Move the current column one to the left
X	Hide the current column from the view
A	Toggle the _arrival metadata column showing when each row was received

Pivoting

Key	Action
U	Mark the selected column as part of a composite key to group records by, adding a count column pinned to the left
enter	While over a composite key column, dive into the data behind the pivot

When a pivot is active, the view focuses on just the key columns and count. If new data streams in, all columns are automatically revealed so you can see the full row detail alongside the updated counts.

Filtering

Key	Action
f	Filter the current column and prompt for a filter
F	Filter the current column by the highlighted cell
e	Exclude from the current column and prompt for a value
E	Exclude the current column by the highlighted cell
\|	Filter ALL columns and prompt for a filter
&	Apply the current search as a filter across all columns
@	Set a time window to show only recent rows (e.g. 5m, 1h, 30s). Append + for rolling mode (e.g. 5m+). Prefix with a column name to filter by parsed timestamps (e.g. timestamp 5m). Use -> to convert a column's format (e.g. timestamp -> relative, ts -> UTC>US/Eastern %H:%M)

Searching & Highlighting

Key	Action
/	Prompt for a search value and jump to the first match
*	Search all columns for the current highlighted cell value
n	Jump to the next match
p	Jump to previous match
+	Pin the current search as a persistent highlight — opens a color picker to choose the highlight color. Duplicate patterns are blocked. Press + with no active search to clear all highlights.
-	Select a pinned highlight to navigate between its matches with n/p, select the 🎨 option to recolor it, or select the 🗑 option to remove it. Each highlight shows its match count.

Sorting

Key	Action
s	Toggle ascending/descending sort on the current column
a	Show aggregations for the current column (count, distinct, sum, avg, min, max)

Output

Key	Action
W	Prompt for a file to write the current buffer to — format is inferred from extension (.csv, .tsv, .json, .jsonl, .txt, .log); - writes CSV to stdout
y	Copy the contents of the currently highlighted cell to the clipboard

Shell Commands

Key	Action
!	Run a shell command and pipe its output into a new buffer

Delimiter / File Parsing

Key	Action
D	Swap the delimiter on the fly (common delimiters, regex with named capture groups, raw, json, or for double-space aligned output like kubectl)
d	Split a column into more columns using a columnar delimiter (json, regex with named capture groups, or any string)
P	Auto-detect a known log format (syslog, Apache, Spring Boot, etc.) and apply it as a regex delimiter

JSON

Key	Action
J	Select a JSON field under the current cell to add as a column

Tail Mode

Key	Action
t	Toggle tail mode — keep the cursor at the bottom as new data arrives
x	Reset new-line highlights — clear the highlighting on streamed rows

Excluded Lines

Key	Action
~	View excluded lines — rows that failed to parse or were removed by filters. Chained ~ buffers accumulate exclusions from all ancestors

Themes & Keymaps

Key	Action
T	Open the theme selector to switch color schemes
K	Open the keymap selector to switch keybinding presets

Sessions & Views

Key	Action
S	Open the session menu — save, load, rename, or delete sessions. Sessions capture your entire workspace (all buffer groups and their state) tied to a specific data source. When opening a file that matches a saved session, nless prompts to restore it.
v	Open the view menu — save, load, rename, or delete views. Views capture a single buffer's analysis settings (filters, sort, columns, highlights) and can be applied to any dataset. Undo restores the buffer to its previous state.

Help

Key	Action
?	Show the help screen with all keybindings
#	Show the caption overlay — displays action descriptions inline as you press keys

Ex Mode

Press : to open the ex-mode command prompt. Ex mode supports the following commands:

Command	Alias	Action
s/pat/rep/		Substitute pattern in the current column
s/pat/rep/g		Substitute pattern in all columns
sort <col> [asc\|desc]		Sort by column name (cycles if no direction given)
filter <col> <pat>	f	Filter column by pattern
exclude <col> <pat>	e	Exclude matches from column
w [path]	write	Write buffer to file (prompts if no path)
o <path>	open	Open file in a new group
q	quit	Close buffer or quit
q!	quit!	Pipe to stdout and exit
set theme <name>		Switch theme
set keymap <name>		Switch keymap
delim <d>	delimiter	Change delimiter
:<number>		Jump to line number
:<number>%		Jump to percentage of file (e.g. :50% jumps to the middle)
help		Show the help screen

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Mouse Interactions

nless supports mouse interactions alongside keyboard controls.

Click Actions

Target	Click	Action
Column header	Left-click	Sort by that column (click again to reverse)
Pivot row	Double-click	Drill into the data behind the pivot (same as enter)
Buffer tab	Left-click	Switch to that buffer
Group bar	Left-click	Switch to that buffer group
Help hint	Left-click	Open the help screen
Menu bar item	Left-click	Open the menu dropdown

Hover Effects

Target	Effect
Column header	Header cell highlights on hover
Group bar	Group label highlights on hover
Menu bar	Switches to hovered menu when a dropdown is already open

Scroll

Action	Effect
Scroll up	Move cursor up 3 rows
Scroll down	Move cursor down 3 rows

Context Menus (Right-Click)

Right-click different elements to open a context menu with relevant actions.

Data cell:

Action
Copy cell
Search cursor word
Filter by value
Exclude value
Add highlight
Sort column

Column header:

Action
Sort column
Pin/unpin column
Hide column
Move left / Move right
Split column
Pivot

Buffer tab:

Action
Rename buffer
Close buffer

Group bar:

Action
Rename group
Close group

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Menu Bar

The menu bar provides mouse-driven access to all major actions. Click a menu label to open it, or hover to switch between menus when one is already open. Each menu item shows its keyboard shortcut.

File

Item
Open file
New buffer
Rename buffer
Merge buffers
Rename group
Write to file
Run command
Close buffer

View

Item
Show/hide columns
Jump to column
Toggle arrival timestamps
Toggle tail mode
Column aggregations
View excluded lines
Reset highlights
Select theme
Select keymap
Sessions
Views

Data

Item
Change delimiter
Split column
Extract JSON key
Auto-detect log format
Time window

Search

Item
Search
Next match
Previous match
Search to filter
Filter column
Exclude from column
Filter all columns
Add highlight
Navigate highlights