VisiData — Terminal Spreadsheet Multitool for Data Exploration

Introduction

VisiData is a terminal-based tool for rapid exploration and manipulation of tabular data. It opens virtually any structured data format instantly and provides a keyboard-driven interface for sorting, filtering, aggregating, and joining datasets without writing code.

What VisiData Does

• Opens CSV, TSV, JSON, SQLite, Postgres, Excel, Parquet, HDF5, and 30+ other formats
• Provides instant frequency analysis, histogram, and pivot table generation
• Supports regex search, column transformations, and Python expressions inline
• Saves modified data back to any supported format
• Handles datasets with millions of rows via lazy loading and streaming

Architecture Overview

VisiData is a pure-Python application built on the curses library. Each data source is loaded through a format-specific loader plugin that yields rows lazily. The sheet abstraction manages columns, types, and sort state. A command system maps single keystrokes to operations, and users can extend functionality with Python snippets in a .visidatarc file.

Self-Hosting & Configuration

• Install via pip, pipx, conda, or your distro's package manager
• No external dependencies for CSV/JSON; install optional packages for databases (psycopg2) or Parquet (pyarrow)
• Customise keybindings and default options in ~/.visidatarc
• Set options.color_default and theme options for terminal colour schemes
• Use --play to replay saved command logs for reproducible analyses

Key Features

• Opens any data format with a single command and no schema definition
• Keyboard-driven workflow is faster than GUI tools for exploratory analysis
• Frequency sheets and pivot tables are one keystroke away
• Command logging enables fully reproducible data exploration sessions
• Extensible via Python plugins and inline expressions

Comparison with Similar Tools

• pandas — requires writing Python code; VisiData is interactive and visual
• csvkit — focused on CSV command-line operations; VisiData adds an interactive TUI
• Miller — streaming record processor; VisiData adds spreadsheet-style navigation
• q — SQL on CSV files; VisiData supports SQL and many more formats interactively
• Tad — GUI CSV viewer; VisiData runs in any terminal without a display server

FAQ

Q: Can it handle very large files? A: Yes. VisiData streams rows lazily and can handle multi-gigabyte files if sufficient memory is available for the visible window.

Q: Is it scriptable? A: Yes. Command logs can be saved and replayed, and .visidatarc supports arbitrary Python.

Q: Does it modify the source file? A: No. Changes exist in memory until you explicitly save to a file.

Q: What Python version is required? A: Python 3.8 or later.

Sources

• https://github.com/saulpw/visidata
• https://www.visidata.org