nothing-less 1.10.3

A TUI paging application with enhanced support for tabular data and real-time streaming

nless

Excel for logs — pipe in anything, wrangle it into columns.

Documentation · Tutorials · Keybindings · Install

nless is a TUI pager for exploring and analyzing tabular data with vi-like keybindings, built on Textual. It reads from stdin, files, or shell command output — automatically inferring structure so you can filter, sort, pivot, and reshape on the fly. Works with CSV, TSV, JSON, logs, and any delimited output.

Installation

pip install nothing-less

or

brew install mpryor/tap/nless

Requires Python 3.13+.

Usage

kubectl get events -w | nless    # stream K8s events
cat access.log | nless           # explore log files
nless data.csv                   # open CSV directly
nless < output.json              # redirect a file

Press ? inside nless to view all keybindings.

Demos

CSV — open, search, filter, sort, pivot

JSON — pipe in API responses, auto-detect keys as columns

Regex — parse raw logs into columns with named capture groups

Pipe mode — use nless as a pipeline stage

Why nless?

I frequently need to dissect streaming tabular data — server logs, kubectl output, CSV exports, CI pipelines. None of the existing tools had exactly the feature set I wanted, so I built nless to complement your workflow.

• Zero config — pipe in anything and nless infers the structure. No schemas, no format flags, no setup.
• Stream-native — built for data that's still arriving. Tail mode, arrival timestamps, and time window filtering come standard.
• Vi-native — if you know Vim, you know nless. Every action is a single keypress away.
• One tool, many formats — CSV, TSV, JSON, space-aligned, regex, raw. Switch between them on the fly without leaving the pager.

Features

• Delimiter inference & swapping — auto-detects CSV, TSV, space-aligned, JSON, and more; swap on the fly with D, or use regex with named capture groups
• Filtering & searching — filter by column, cell value, or search match; exclude rows; full-text search with match navigation
• Sorting & pivoting — one-key sort on any column; group by composite key with summary view and drill-in
• Streaming & tail mode — live-updating as new data arrives, with arrival timestamps and time window filtering
• JSON & log parsing — extract nested JSON fields into columns; parse unstructured logs with regex
• Pipe mode — use nless as a pipeline stage with Q to pipe and exit, or --no-tui for batch mode

All features

• Buffers — mutating actions create a new buffer, letting you jump up and down your analysis history
• Delimiter swapping — swap between CSV, TSV, space-aligned, JSON, regex with named capture groups, and raw mode on the fly with D
• Column delimiters — split a column into more columns using JSON, regex, or string delimiters with d
• Filtering — filter by column (f/F), exclude (e/E), across all columns (|), or from a search (&)
• Sorting — toggle ascending/descending sort on any column with s
• Searching — search (/), search by cell value (*), navigate matches (n/p)
• Pivoting — group records by composite key with U, focused summary view, dive into grouped data with enter
• Column management — show/hide columns (C), reorder columns (</>)
• JSON extraction — promote nested JSON fields to columns with J
• Shell commands — run a shell command and pipe its output into a new buffer with !
• Tail mode — keep the cursor at the bottom as new data arrives with t
• Output — write buffer contents to a file or stdout (W), copy cell values (y)
• Themes — 10 built-in color themes (Dracula, Nord, Gruvbox, etc.) plus custom theme support, switch with T
• Arrival timestamps — every row records when it was received; toggle the _arrival column with A
• Time window filtering — show only recent rows with @ (e.g. 5m, 1h); append + for rolling windows
• Raw pager mode — --raw or auto-detected; a fast virtual-rendering pager for unstructured text, handling million-line files without columnar overhead
• Excluded lines — view lines that failed to parse or were removed by filters with ~, with chained accumulation across buffers
• Pipe mode — use nless as a pipeline stage; interactive exploration with Q to pipe and exit, batch mode with --no-tui, or --tui to force interactive mode
• Mouse support — click column headers to sort, double-click pivot rows to drill in, right-click for context menus, and navigate via the menu bar
• Merge files — combine multiple files into a single view with a _source column using --merge
• Update notifications — background PyPI version check with non-blocking toast notifications

Full keybinding reference

Buffers:

• [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 the program if all buffers are closed
• Q - pipe current buffer to stdout and exit immediately (pipe mode shortcut)
• N - create a new buffer from the original data
• r - rename the current buffer
• M - merge the current buffer with another buffer

Groups:

• } - 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

Navigation:

• 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:

• 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
• > - move the current column one to the right
• < - move the current column one to the left
• A - toggle the _arrival metadata column showing when each row was received

Pivoting:

• 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

Filtering:

• 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); append + for rolling

Searching & Highlighting:

• / - 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
• - - navigate or manage pinned highlights

Output:

• W - prompt for a file to write the current buffer to (- writes to stdout)
• y - copy the contents of the currently highlighted cell to the clipboard

Shell Commands:

• ! - run a shell command and pipe its output into a new buffer

Tail Mode:

• t - toggle tail mode
• x - reset new-line highlights

Sessions & Views:

• S - open the session menu (save, load, rename, delete)
• v - open the view menu (save, load, rename, delete)

Themes & Keymaps:

• T - open the theme selector
• K - open the keymap selector

Excluded Lines:

• ~ - view excluded lines (parse failures + filtered rows), with chained accumulation

Sorting & Aggregations:

• s - toggle ascending/descending sort on the current column
• a - show column aggregations (count, distinct, sum, avg, min, max)

JSON:

• J - select a JSON field under the current cell to add as a column

Delimiter/file parsing:

• 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 and apply it as a regex delimiter

Help:

• ? - show the help screen with all keybindings

Mouse:

• Left-click column headers to sort
• Double-click pivot rows to drill in
• Right-click cells, headers, tabs, or groups for context menus
• Click buffer tabs or group bar to switch
• Menu bar for mouse-driven access to all actions

See the full keybinding reference and tutorials for more.

Contributing

Contributions are welcome! Please open an issue or a pull request — check out the contributing guidelines for more information.

Alternatives

Shout-outs to all of the below wonderful tools! If nless doesn't have what you need, they likely will:

	nless	VisiData	csvlens	lnav	Toolong
Focus	Tabular data pager	Data multitool	CSV viewer	Log navigator	Log viewer
Language	Python	Python	Rust	C++	Python
Streaming / stdin	:white_check_mark:	:heavy_minus_sign:	:heavy_minus_sign:	:white_check_mark:	:white_check_mark:
Delimiter inference	:white_check_mark:	:heavy_minus_sign:	:heavy_minus_sign:	:x:	:x:
Vi keybindings	:white_check_mark:	:white_check_mark:	:white_check_mark:	:white_check_mark:	:x:
Filtering	:white_check_mark:	:white_check_mark:	:heavy_minus_sign:	:white_check_mark:	:x:
Sorting	:white_check_mark:	:white_check_mark:	:white_check_mark:	:heavy_minus_sign:	:x:
Pivoting / grouping	:white_check_mark:	:white_check_mark:	:x:	:heavy_minus_sign:	:x:
JSON parsing	:white_check_mark:	:white_check_mark:	:x:	:white_check_mark:	:heavy_minus_sign:
Log format detection	:white_check_mark:	:x:	:x:	:white_check_mark:	:heavy_minus_sign:
Regex column parsing	:white_check_mark:	:white_check_mark:	:x:	:white_check_mark:	:x:
Pipe mode	:white_check_mark:	:white_check_mark:	:heavy_minus_sign:	:heavy_minus_sign:	:x:
Raw text pager	:white_check_mark:	:heavy_minus_sign:	:x:	:white_check_mark:	:white_check_mark:
Themes	:white_check_mark:	:white_check_mark:	:heavy_minus_sign:	:white_check_mark:	:x:
SQL queries	:x:	:x:	:x:	:white_check_mark:	:x:
Python expressions	:x:	:white_check_mark:	:x:	:x:	:x:
Timestamp parsing	:x:	:x:	:x:	:white_check_mark:	:white_check_mark:
Multi-file merge	:white_check_mark:	:white_check_mark:	:x:	:white_check_mark:	:white_check_mark:

:white_check_mark: full support · :heavy_minus_sign: partial · :x: not supported