Tennis

tennis is a small CLI for printing stylish CSV tables in your terminal. Rows will be truncated to fit and it'll automatically pick nice colors to match your terminal. Written in Zig. Demo:

Installation

Brew/macos

$ brew install gurgeous/tap/tennis

Linux tarball

Download a binary from https://github.com/gurgeous/tennis/releases. Copy into your path somewhere. I like to use ~/.local/bin personally. Also see the (optional) bash/zsh completions and man page in extra/.

Build from source

# this will build zig-out/bin/tennis
$ mise trust && mise install
$ zig build

Important Features

• auto-layout to fit your terminal window
• auto-themes to pick light or dark based on your terminal background
• auto-format numbers
• auto-detect csv vs tsv (or semis, or pipes)
• titles, row numbers, border styles...

Options

 Usage: tennis [options...] <file.csv>     # print file.csv
        tennis [options...]                # print csv from stdin

  -n, --row-numbers         Turn on row numbers
  -t, --title <string>      Add a title to the table

      --border <border>     Table border style (rounded|thin|double|...)
      --color <color>       Turn color off and on (on|off|auto)
      --completion <shell>  Print a shell completion script (bash|zsh)
      --delimiter <char>    CSV delim (can be any char or "tab")
      --digits <int>        Digits after decimal for float columns (1-6)
      --head <int>          Show first N rows
      --tail <int>          Show last N rows
      --theme <theme>       Select color theme (auto|dark|light)
      --vanilla             Disable numeric formatting entirely
      --width <int>         Set max table width in chars
      --help                Get help
      --version             Show version number and exit

Note that color defaults to on. Tennis likes to be colorful.

An Aside: Term Background

tennis uses a termbg.zig module to detect the terminal background color so it can choose the correct theme (dark or light). Detection is complicated, and I'm calling it out here because I don't think anyone has implemented this in Zig yet.

Future Work

• support for input.json (and maybe ndjson/jsonl)
• show first/last rows - --head, --tail
• sort rows - --sort
• select cols - --only or --col or --columns or --select
• pipe through less - --pager
• add zebra stripes - --zebra
• output markdown --format markdown or --markdown
• watch a file, update display --watch
• briefly summarize each col --summary or --peek

Similar Tools

We love CSV tools and use them all the time! Here are a few that we rely on:

• bat - syntax highlights csv files, and many others
• csvlens, tabiew & tidy viewer - great viewers for CSV files, beautiful and fun
• miller - csv processing and transformation
• nushell - modern shell with first-class structured table data
• qsv - filter, sort, combine, join... (a fork of xsv)
• Terminal::Table - wonderful rubygem for pretty printing tables, great for non-hash data like confusion matrices
• visidata - the best for poking around large files, it does everything
• table_tennis - my own project, the basis for this one

Changelog

0.0.4 (unreleased)

• --border styles based on Nushell / tabled crate.
• --completion for auto-generating bash/zsh completions
• --head and --tail for clipping large tables
• doomicode, best-effort Unicode width for emojis, etc
• auto-detect csv vs tsv (or semis, or pipes)

0.0.3 (Mar '26)

• Custom --delimiter for tsv, semicolon, etc. #5 (@markhm)
• Auto numeric formatting, including delims and rounding for int/float columns. Disable with --vanilla.
• man page & shell completions

0.0.2 (Mar '26)

• Initial release.

Special Thanks

• termbg and termenv for showing how to safely detect the terminal background color. These libraries are widely used for Rust/Go, but as far as I know nothing similar exists for Zig.
• I copied the header color themes from tabiew. Great project!
• Border styles pinched from nushell and tabled crate. Thanks guys!