nless

excel for your 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. Pipe in anything and nless infers the structure so you can filter, sort, pivot, and reshape without config. Works with CSV, TSV, JSON, logs, and any delimited output.

Installation

pipx install nothing-less

or

brew install mpryor/tap/nless

Requires Python 3.13+ for pipx/pip installs. You can also use pip install nothing-less if you prefer. The Homebrew formula manages its own Python dependency.

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 explore 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.

• Zero config — pipe in anything and nless infers the structure.
• Stream-native — built for data that's still arriving, with streaming features like tail mode, arrival timestamps, and time window filtering.
• Vi-native — if you know Vim, nless should feel familiar. If you don't, choose from the other built-in keymaps or build your own.
• Mouse-friendly — click column headers to sort, double-click pivot rows to drill in, right-click for context menus, navigate via the menu bar.
• One tool, many formats — CSV, TSV, JSON, space-aligned, regex, raw. Switch between them without leaving the pager.

Features

• Delimiter inference & swapping — auto-detects CSV, TSV, space-aligned, JSON, and more. Swap 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 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. Prefix with a column name to filter by parsed timestamps (e.g. timestamp 5m).
• Timestamp parsing & conversion — auto-detects datetime columns (epoch, ISO 8601, syslog, etc.) for type-aware sorting. Convert formats with @colname -> target (epoch, iso, relative, strftime, with optional timezone conversion). Also available from the CLI with --format-timestamp / -F for batch pipelines.
• 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, navigate via the menu bar.
• Merge files — combine multiple files into a single view with a _source column using --merge.

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; prefix with column name for column-based filtering (e.g. timestamp 5m); use -> for format conversion (e.g. timestamp -> relative)

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! See the contributing guidelines for details.

Alternatives

If nless doesn't have what you need, check out these other great tools:

	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	✅	➖	➖	✅	✅
Delimiter inference	✅	➖	➖	❌	❌
Vi keybindings	✅	✅	✅	✅	❌
Filtering	✅	✅	➖	✅	❌
Sorting	✅	✅	✅	➖	❌
Pivoting / grouping	✅	✅	❌	➖	❌
JSON parsing	✅	✅	❌	✅	➖
Log format detection	✅	❌	❌	✅	➖
Regex column parsing	✅	✅	❌	✅	❌
Pipe mode	✅	✅	➖	➖	❌
Raw text pager	✅	➖	❌	✅	✅
Themes	✅	✅	➖	✅	❌
SQL queries	❌	❌	❌	✅	❌
Python expressions	❌	✅	❌	❌	❌
Timestamp parsing	✅	❌	❌	✅	✅
Multi-file merge	✅	✅	❌	✅	✅

✅ full support · ➖ partial · ❌ not supported