Pretty-printing is dropped by necessity
Each record must occupy exactly one line, so indentation and line breaks inside records are removed. The data is unchanged; only the whitespace is.
Convert JSON to JSONL
A JSON array has to be parsed in full before you can touch the first record. JSON Lines does not. This converter unwraps the array and writes each record on its own line, which is what bulk loaders and streaming consumers want.
- Runs in your browser
- No signup
- No upload
- Free
JSONJSONL
Runs on your deviceCSV
Options
Reading JSON
Auto-detect reads the first rows and picks the separator that splits them consistently.
Turn off when the file starts straight into data. Columns are then named column_1, column_2, and so on.
Turns "42" into a number and "true" into a boolean. Values with leading zeros stay text so IDs and zip codes survive.
Which worksheet to convert. Filled in once the workbook is read.
Dotted path to the array of records, such as data.items. Leave empty to use the whole document.
Turns {"user":{"id":7}} into a user.id column. Arrays are kept as JSON text.
Pick the encoding the file was written in. Wrong encoding shows up as garbled accents.
Comma-separated words that should become null instead of text.
Writing JSONL
Snappy is the default across Spark, DuckDB and pandas. Gzip is smaller but slower to read.
Turns a user.id column back into {"user":{"id":7}}.
Excel needs a byte order mark to open UTF-8 files with accents correctly.
Rows per row group. Larger groups compress better; smaller groups let readers skip more.
Converting…
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Work with Parquet as well?See ParquetReader with ParquetReader — opens Parquet files directly.What happens
How this converter handles JSON to JSONL
- Reads the JSON document and locates the record array, unwrapping a single-array envelope if present.
- Writes one compact JSON object per line, in the original order.
- Keeps values as they were — no retyping, since JSON types are already explicit.
- Flattens nesting only if you ask it to; otherwise records keep their structure.
Format differences
JSON vs JSONL
Nested, self-describing records that every language can read. One JSON object per line, built for streaming and appending.
| JSON | JSONL | |
|---|---|---|
| Type information | Strings, numbers, booleans, null | Strings, numbers, booleans, null |
| Structure | Nested objects and arrays | One nested object per line |
| Compression | None | None |
| Typical file size | Largest — keys repeat on every record | Slightly under JSON |
| Schema | Implicit, per record | Implicit, per line |
| Human-readable | Yes, though verbose | Yes, one record at a time |
| Tool support | Every language, natively | Log pipelines, LLM training sets, BigQuery |
Worth knowing
What to watch out for
A single object becomes a single line
If the input is one object rather than an array, the output is one line. That is valid JSONL, if a short file.
Nesting is preserved by default
Unlike conversions to tabular formats, nested objects stay nested here — JSONL can represent them natively. Flattening is opt-in.
When you need this
Common reasons to convert JSON to JSONL
Preparing a bulk import
BigQuery, Elasticsearch and many warehouse loaders take newline-delimited JSON directly.
Making a large export processable
Line-based tools can stream a JSONL file that would not fit in memory as a single array.
Building an append-friendly log
New records can be appended to a JSONL file without rewriting it. A JSON array cannot be appended to without editing the closing bracket.
FAQ
JSON to JSONL questions
Is my file uploaded?
No. The conversion runs in your browser using WebAssembly and JavaScript. The file is read from your disk into a Web Worker, converted in memory, and handed back as a download. It is never sent to a server, so there is nothing for us to store, log or leak.
Does this change my data?
No. Only the framing changes — the array wrapper and the whitespace. Values, types and record order are preserved.
Why would I prefer JSONL over JSON?
Because it streams and appends. A consumer can process record one without having read record one million, and new records can be appended without rewriting the file.
What if my JSON is an object with an array inside?
The array is detected and unwrapped automatically. For deeper structures, set a record path such as result.items.
Can I go back the other way?
Yes — the JSONL to JSON converter wraps the lines back into an array.
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