What is qsv?

qsv is a blazing-fast, feature-rich command-line program for working with CSV and tabular data. It is a successor to the popular xsv tool, written in Rust for maximum performance. qsv provides over 50 commands for querying, slicing, sorting, analyzing, filtering, enriching, transforming, validating, joining, formatting, and converting data. Beyond CSV, it supports Excel, Parquet, Arrow, Avro, JSON, JSONL, and TSV formats.

The tool is designed for composability—commands can be piped together in Unix-style workflows. With Polars integration for multithreaded processing, qsv can count rows in a 15GB, 27-million-row dataset in under 12 seconds, or instantly with an index.

Key Commands and Features

Notable commands include apply for string, date, math, and NLP transformations (sentiment analysis, language detection, name gender guessing); join for inner, outer, and cross joins using hash indexes; validate for checking data against JSON Schema definitions; frequency for building column frequency tables with parallelism; sqlp for running SQL queries directly against CSV files via Polars; and luau for custom Lua scripting.

qsv also includes a describegpt command that uses LLMs to generate natural-language descriptions of datasets, and a chat command for conversational data exploration. The clipboard command allows direct input/output from the system clipboard for interactive workflows.

Installation and Output

Install via cargo install qsv, Homebrew, Scoop, or download pre-built binaries from GitHub releases. qsv outputs clean CSV, JSON, or formatted tables to stdout, making it trivially composable with other CLI tools and pipeline orchestration systems. It is published on crates.io, has over 3,500 GitHub stars, uses the Unlicense (public domain), and receives daily commits from active maintainers.