jq

jq is a command-line JSON processor that runs filters over JSON from stdin or files and emits transformed results to stdout. It is a core shell primitive for inspecting, validating, reshaping, and generating structured data between other commands.

• Extract fields, filter arrays, join values, and reshape JSON payloads from APIs, config files, logs, and other CLI output.
• Validate and pretty-print JSON, or emit compact, sorted, raw-string, or JSON-seq output for downstream commands.
• Build JSON from scratch with -n, pass structured values with --argjson or --jsonargs, and handle very large documents with --stream.

• Default stdout is structured JSON, and -c or --seq keep it easy to pipe into follow-up steps.
• It works cleanly in non-interactive stdin or file workflows, with exit codes and stderr behavior that suit inspect, transform, and verify loops.
• Best used as a companion primitive around other tools that emit JSON; agents still need to learn jq syntax for complex reductions and streaming transforms.

• It does not authenticate to services or mutate remote systems on its own; it only transforms local input and output streams.
• Shell quoting and the filter language are common failure points on first attempt, especially across different shells.