gron

gron — Make JSON Greppable

gron turns JSON into flat, line-oriented assignments so every value carries its full path. gron -u (ungron) rebuilds JSON from those lines. This makes rg/grep a viable JSON query tool when you don't yet know the structure or the jq path.

When to use gron vs jq

• gron — you don't know the shape yet; you want to discover where a key/value lives, or grep across deeply nested JSON without writing a path expression.
• jq (/jq-json-processor) — you already know the structure and want to reshape, aggregate, or project fields.

A common flow is gron to find the path, then jq to extract it cleanly.

Core usage

gron data.json                      # flatten to: json.foo.bar[0] = "x";
cat data.json | gron                # from stdin
gron data.json | rg <pattern>       # grep flattened lines for a key or value
gron data.json | rg <pattern> | gron -u   # rebuild JSON from just the matched lines
curl -s <url> | gron | rg <pattern>        # explore an unfamiliar API response

Useful flags

Flag	Effect
-u, --ungron	Reverse: reassemble JSON from gron output
-v, --values	Print only values, not the full assignment
-s, --stream	Treat input as a stream of one JSON object per line (JSONL)
--no-sort	Preserve original key order (default sorts keys)
-m, --monochrome	Disable colour (default when piped)

Recipes

Find the path to a value you can see but can't locate:

gron config.json | rg -i "timeout"
# -> json.server.http.timeout_ms = 30000;

Extract a subtree by grepping paths, then rebuild valid JSON:

gron response.json | rg '^json\.data\.users\[\d+\]\.email' | gron -u

Diff two JSON docs semantically (order-independent):

diff <(gron a.json) <(gron b.json)

Agent notes

• gron output is already line-bounded — cap with | head -n N (Bash) / Select-Object -First N (PowerShell) like any other stream before it reaches context.
• For raw byte-stream pipelines (gron | rg | gron -u) on Windows, run via the Bash tool so streams pass correctly (PowerShell's | passes objects, not bytes).
• Once you know the path, prefer a single jq projection over re-running gron for repeated extracts.