Miller

What Miller is

Miller is a free, open-source command-line tool for querying, reshaping, and converting data files. It supports CSV, TSV, ASV, USV, JSON, JSON Lines, YAML, PPRINT, Markdown, XTAB, DKVP, DKVPX, NIDX, DCF, and recutils. Users can add or remove fields, sort records, calculate aggregate statistics, pretty-print data, and convert formats. Miller works with named fields in key-value data, so users do not need to keep track of positional column numbers. It can also handle interleaved records with different field names. Most operations process one record at a time, which can allow suitable operations on files larger than available RAM. Miller runs on Linux, macOS, and Windows and can be self-hosted. Written in Go, it has no runtime dependencies and can be downloaded or compiled as a single binary. Installation options include package managers and building from source. Its documentation describes it as complementary to R, pandas, SQL databases, and Unix tools. The executable also includes an MCP server using JSON-RPC over stdin/stdout without opening a network port.