JQ Tutorial

Learn jq, the command-line JSON processor, one exercise at a time.

jq lets you slice, filter, map, and transform JSON straight from the command line — no script required for most everyday tasks like pulling a field out of an API response or reshaping a config file.

This tutorial walks through jq's core building blocks — identity, field access, indexing and slicing, pipes, and filters — with a real input and expected output for every step. You type an expression, we check it against jq's actual output, so what you learn here works exactly the same in your terminal.

What you'll practice (27 steps)

Identity: .
Object field: .foo
Nested fields: .foo.bar
Bracket keys: .["foo"]
Optional access: .foo?
Array index: .[0]
Slice: .[1:3]
Iterate: .[]
Pipe: |
Comma: ,
Collect into an array: [ ]
Build objects: {a, b}
Rename keys: {new: .old}
Computed values: {k: (expr)}
String interpolation: \(expr)
Inspect: keys, length, has
Filter with select()
Transform with map()
map(select(...)) — filter arrays
Order: sort_by, unique
Bucket with group_by()
Aggregate with add
Reshape: to_entries / from_entries
Fold with reduce
Defaults: the // operator
Recursive descent: ..
Capstone: put it together

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