JSON to JSON Lines (NDJSON) Converter
Convert a JSON array into JSON Lines (NDJSON, one object per line) and back, in both directions.
What JSON Lines (NDJSON) is
JSON Lines (also called NDJSON, Newline Delimited JSON) is a format where each line is a valid JSON object on its own, instead of a single array wrapping all of them. It's used by logging systems, data pipelines (Elasticsearch bulk, BigQuery, Spark) and APIs that stream results, because it can be processed line by line without loading the whole file into memory.
JSON → JSON Lines
The input JSON must be an array of objects, e.g. [{...}, {...}]. Each array item becomes its own line.
JSON Lines → JSON
Each non-empty line is parsed as an independent JSON object and all of them are grouped into a single JSON array. If a specific line isn't valid JSON, you're told exactly which line number has the error.