Inspecting a log export
Convert and the records become readable. If the file was truncated by a crash, the error tells you exactly which line to remove.
JSONL to JSON
Turn JSON Lines into a single formatted JSON array in your browser.
Maintained by Roshan.
Use JSONL to JSON
Converts JSON Lines into JSON array in this tab. Configuration files routinely hold hostnames, keys and credentials, so nothing here is sent anywhere.
Values are never retyped as numbers or booleansGuessing types is how a converter turns a postcode of 0123 into 123, or a literal string of false into a boolean. Values are carried across as they were written, and casting is left to you where it matters.
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Browse all developer and data toolsAbout JSONL to JSON
Reading a JSON Lines file by eye is unpleasant. Each record is compact by necessity, which means one long unbroken line per entry, and finding the record you care about among thousands of them is genuinely difficult. Converting to a formatted array makes it readable and lets ordinary JSON tooling work on it. The feature that matters most here is not the conversion itself but the error handling. A JSONL file is usually machine-generated, often by something that was appending to it while a process crashed, and a single truncated record in the middle of a large file will break any parser. A generic error saying the JSON is invalid is nearly useless in that situation. This one names the line number and shows the start of the offending record.
Work through the input
- Each non-empty line is parsed as an independent JSON value and collected into an array.
- Blank lines are skipped rather than treated as errors, since trailing newlines and gaps are common in appended files.
- If a line fails to parse, the error names its line number and shows the beginning of the text, which is the difference between a two-second fix and a long search.
- The result is written as a formatted array with indentation, which is what makes the data readable again.
- Record order is preserved exactly, since in log and event data the order is usually meaningful.
When jsonl to json is useful
Loading a dataset into a tool that wants an array
Many editors and viewers expect standard JSON. This is the bridge.
Check the output
- The whole file is held in memory to build the array. That is fine for the sizes a browser handles, but it is the opposite of what JSONL was designed for.
- Records with different shapes are combined without complaint. JSONL permits that, so the resulting array may be heterogeneous.
- A truncated final record, which is common when a process was killed mid-write, will be reported as an error rather than silently dropped.
- Comments are not supported, since neither format allows them.
- Very large files are better processed with a streaming tool. The point of JSONL is to avoid loading everything at once, which this conversion necessarily does.
Questions about JSONL to JSON
What happens if one record is broken?
The conversion stops and names the line number, showing the start of that record. Finding one bad line in ten thousand is otherwise very hard.
Are blank lines a problem?
No. They are skipped, since trailing and intervening blank lines are common in files written by appending.
Is the order preserved?
Yes, exactly. For logs and event streams the order usually carries meaning.
Can records have different structures?
Yes. JSONL allows it and the array simply contains different shapes.
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