JSON Flattener

JSON Flattener

Convert nested JSON objects and arrays into path-and-value rows.

{"user":{"name":"Ada"},"rows":[3,5]}

user.name = Ada
rows.0 = 3
rows.1 = 5

Object keys join with the selected separator; array positions use numeric segments such as rows.0. Empty keys remain path segments: {"":{"b":1}} becomes .b = 1. Null, false and zero are retained; empty objects and arrays produce no entries. Identical flattened paths stop the operation with an error: change the separator or source key names. No escaping or unflatten operation is provided.

Pasted text takes priority; the selected file is read only when the text box is empty. A blank separator uses a period. Pasted input is limited to 16777216 UTF-16 code units, one file to 64 MiB, nesting to 200 and primitive leaves to 100000; exceeding a limit is rejected, not truncated. JSON uses JavaScript numbers, so large integers can round; store exact identifiers as strings. CSV always has path,value, commas and quoted fields; quotes do not neutralise spreadsheet formulas. Review, copy or separately download json-flattened.txt.