Step 1 / source
Choose the source
Drop one file here
Choose an NDJSON or JSON Lines export where each logical record is complete on one physical line.
Checking publication status...LOCAL DATA CONVERTER / JSON LINES TO ARRAY
NDJSON to JSON
Validate one complete JSON value on every NDJSON line and combine up to 50,000 values into a standard downloadable JSON array.
Processed in this browserOne UTF-8 .ndjson or .jsonl file up to 5 MB, with at most 50,000 non-empty lines and 20 MB output. Each line must hold exactly one complete JSON value.
NDJSON - 50,000 lines
No file upload
This operation runs with browser APIs. Nirmion receives catalogue requests, not the selected source bytes.
Original stays unchanged
The converter creates a separately named output. It never writes back into the source file.
Bounded work
One UTF-8 .ndjson or .jsonl file up to 5 MB, with at most 50,000 non-empty lines and 20 MB output. Each line must hold exactly one complete JSON value.
Plain-language method
How JSON lines become one array
Nirmion reads UTF-8 lines, applies the selected blank-line policy, parses each remaining line as one complete JSON value, preserves source order and nested values, and serializes the collected values inside a standard JSON array. A malformed line stops the whole conversion instead of being skipped silently.
- 01Choose a valid source
Each non-empty line must be valid JSON by itself. Pretty-printed multi-line objects are ordinary JSON, not NDJSON, and will fail line validation.
- 02Review the conversion choices
Skip tolerates visual gaps; Reject enforces a strict stream. Compact minimizes bytes, while two- or four-space indentation improves review.
- 03Inspect the separate result
The output ends in _nirmion_tools_array.json and can be opened by software that expects one standard top-level JSON array.
Useful when
Practical jobs this tool handles
- Turn exported log records into one reviewable JSON file.
- Prepare JSON Lines data for software expecting an array.
- Validate a bounded NDJSON fixture before handoff.
Before converting
Keep one value on each line
- Confirm objects are not pretty-printed across lines.
- Choose whether blank lines should be accepted.
- Review the output count against the source record count.
Know the boundary
Line boundaries are part of the format
A newline inside an unescaped or pretty-printed JSON value creates a new record boundary. This tool does not guess how malformed multi-line values should be reassembled.
Quick answers
Questions before you convert
Independent line parsing makes failures traceable.
Can a line contain a number or string?
Yes. Any complete JSON value is accepted, not only objects.
Are nested objects preserved?
Yes. Valid nested JSON remains nested inside its array item.
Are malformed lines skipped?
No. One invalid non-empty line stops output so record loss is visible.