Overview

jq is a lightweight, portable command-line JSON processor that lets you slice, filter, map, and transform structured JSON data with a concise expression language. It reads JSON from standard input (or files), applies a filter expression, and writes the result to standard output — making it an indispensable tool in any shell-based data pipeline.

What jq Provides

jq treats JSON as first-class data and provides a complete expression language for transforming it. Filters compose with the pipe operator |, enabling you to build complex transformations from small, focused pieces. Because jq is a single statically linked binary with no runtime dependencies, it runs identically in CI/CD pipelines, Docker containers, and developer laptops.

Key Concepts

• Filters: Expressions that consume JSON input and produce JSON output; . is the identity filter that passes input unchanged
• Pipes: The | operator chains filters so output of one becomes input of the next
• Types: jq natively handles null, boolean, number, string, array, and object
• Construction: {} and [] build new objects and arrays from existing data
• Built-in Functions: map, select, group_by, sort_by, reduce, and many more transform collections without explicit loops
• Conditionals: if-then-else, the alternative operator //, and try-catch handle missing fields and type errors gracefully
• Reduce: Fold a stream of values into a single accumulated result
• Path Expressions: path, getpath, setpath, and delpaths manipulate the structural location of values inside JSON documents

Content in This Section

• By Example — Learn jq through 85 heavily annotated examples covering filters, pipes, types, object and array construction, built-in functions, conditionals, reduce, and real-world JSON processing (95% coverage).