JSON Lines Converter guide
Convert newline-delimited JSON records into one JSON array, or write each array value as a compact JSON line.
What this tool does
The JSON Lines Converter supports two related plain-text structures. In JSONL-to-array mode, every non-empty line must contain one complete valid JSON value. The tool parses the lines independently and writes a formatted top-level array. In array-to-JSONL mode, the input must be one valid top-level JSON array; each member is serialized onto its own compact line.
Line numbers are preserved during validation, so an invalid record produces an error naming the source line. Blank lines are ignored when reading JSONL. Values can be objects, arrays, strings, numbers, booleans, or null; the tool does not require every record to share the same shape.
JSON Lines is useful for logs, streaming jobs, command-line processing, and record-oriented data exchange. It is not the same as a pretty-printed JSON document where one object spans several lines. A multiline object must be compacted to one physical line before it is valid JSONL.
How to use it
- Select JSONL to array or Array to JSONL.
- Paste the complete source text.
- Select Convert records.
- If an error names a line, correct that record and try again.
- Review the record count and copy the converted JSON.
Before replacing production data, compare record counts and sample values from the beginning and end of the output. JSON numbers and strings remain their JSON types, but whitespace and property formatting are normalized during serialization.
Benefits
- Converts in both directions
- Reports the number of converted records
- Identifies invalid JSONL by physical line number
- Accepts all valid JSON value types
- Formats arrays for readable inspection
- Keeps records within the current browser
Limits and large datasets
The complete input and output are held in browser memory. Very large logs are better handled with streaming command-line or data-processing software. The tool also does not validate a business schema, enforce required properties, deduplicate records, or preserve original whitespace and key formatting.