Run jq online

Run jq online — JSON on the command line, sandboxed.

Version

Firecracker microVM live per-test verdicts multi-file compile

jq is `sed for JSON`: a small, sharp DSL for slicing, filtering, mapping, and reshaping JSON on the command line. Every backend engineer eventually memorises `. | .foo[].bar`.

ls-judge runs jq inside a Firecracker microVM — pipe JSON via stdin, apply your filter, get results streamed back.

Starter code

What you get in jq

Clicking "Run now" opens the playground with this exact code and a matching test case pre-loaded — passes on first Run.

jq 1

input | tonumber | . * 2

stdin →

expected →

FAQ

Common questions about jq on ls-judge

jq 1.7 / 1.8?: A recent stable jq — currently the 1.x line.
How do I feed JSON?: Paste JSON into the Test panel's stdin field. Your filter is in the editor.
Free?: Yes.
Multi-line filters?: Yes — the editor treats the whole file as one filter program.