JQ Online Playground

About JQ Online Playground

jq is a lightweight and flexible command-line JSON processor that has become the de facto standard for querying and transforming JSON data in shell pipelines. This online playground brings the full power of jq to your browser by compiling the native jq C implementation to WebAssembly, enabling you to run complex JSON queries without installing any software or sending your data to a server. All processing happens entirely on your local machine, ensuring your sensitive JSON data never leaves your browser.

To use the playground, simply paste or upload your JSON input into the left panel and type a jq filter expression in the filter bar. The output panel instantly displays the filtered or transformed result. The tool supports the complete jq 1.7 grammar, including filters like `.key`, `.[]`, `select()`, `map()`, `group_by()`, `reduce`, and custom function definitions. You can experiment interactively, adjusting your filter until you get exactly the result you need.

jq filters follow a pipeline model similar to Unix shell pipes. A filter takes an input and produces zero or more outputs. The simplest filter is the identity filter `.` which outputs the input unchanged. From there you can chain filters: `.users | map(select(.active)) | .[].name` extracts the names of all active users. Understanding this pipeline metaphor is key to mastering jq expressions and writing efficient filters.

Performance is a key advantage of this playground. Because the jq engine runs as compiled WebAssembly rather than a JavaScript reimplementation, it processes large JSON files at near-native speed. Files of hundreds of megabytes can be queried efficiently within the browser. The tool also supports streaming input for files that are too large to fit in memory, allowing you to process datasets of any size.

Common real-world use cases include extracting specific fields from API responses, transforming JSON between different API schemas, validating JSON structure, generating reports from JSON logs, and debugging complex jq filters before deploying them in production scripts. The playground is also an excellent learning tool for anyone looking to master jq syntax through hands-on experimentation.

For advanced users, the playground supports the full jq module system, including importing libraries with `include` and defining reusable functions. You can also use the `--arg` flag to pass external variables into your filters. The output can be formatted as regular JSON, compact JSON, or raw text using the `-r` flag, giving you complete control over the output format.