Tools

jq Cheat Sheet — Filter and Transform JSON on the Command Line

jq is the command-line tool for slicing JSON — API responses, logs, and config files. These are the filters that cover most real-world use.

Put it into practice with the matching tool.

Basics

jq '.' file.jsonPretty-print JSON

curl -s url | jq '.'Pretty-print an API response

.nameGet a field

.user.address.cityGet a nested field

.["first-name"]Get a field with special characters

.name?Suppress errors if the input is not an object

.[0] / .[-1]First / last element

.[2:5]Slice

.[]Iterate — output each element separately

.items[].idGet one field from every element

lengthLength of an array, object, or string

[.[] | .id]Collect results back into an array

map(.price * 2)Transform every element

map(select(.active))Keep elements where a condition is true

.[] | select(.age > 30)Filter while iterating

sort_by(.date) / reverseSort by a field / reverse an array

group_by(.type)Group into arrays by a field

unique_by(.id)Remove duplicates by a field

first(.[] | select(.ok))First matching element

addSum numbers or concatenate arrays and strings

{id, name}New object with selected fields

{user: .name, n: (.items | length)}New object with computed values

"\(.first) \(.last)"String interpolation

keys / to_entriesObject keys / list of {key, value} pairs

.a // "default"Fallback when a value is null or missing

del(.password)Remove a field

.count += 1Update a value in place

-rRaw output — strings without quotes

-cCompact output, one JSON value per line

-sSlurp all inputs into one array

--arg name "$VAR"Pass a shell variable as $name

-eSet the exit status from the last output (useful in scripts)

.[] | @csvFormat an array as a CSV row (also @tsv, @base64, @uri)

Common JSON Syntax Errors and How to Fix Them