Convert JSONL to JSON, Free
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How to convert JSONL to JSON
JSONL (JSON Lines) stores one valid JSON value per line, making it ideal for streaming data, log files, and machine learning datasets where you want to process records one at a time without loading the entire file into memory. Standard JSON, by contrast, wraps all records in a single array or object. Converting JSONL to JSON wraps the individual lines into a properly formatted JSON array, which is what most APIs, configuration parsers, and developer tools expect.
The conversion runs entirely in your browser using JavaScript. Paste your JSONL text or upload a file, and the converter parses each line as a JSON value, validates it, and joins them into a JSON array. Nothing is uploaded to a server.
Paste or upload your JSONL
Enter your JSONL text in the input box or upload a .jsonl file. Each line must be a valid, complete JSON value.
Validate lines
The converter checks each line for valid JSON syntax and highlights any lines that fail to parse. Fix or remove invalid lines before converting.
Convert to JSON
Click Convert. The converter wraps all valid lines in a JSON array and formats the output with proper indentation.
Copy or download the JSON
Copy the resulting JSON from the output box, or download it as a .json file.
Frequently asked questions
What is the difference between JSONL and JSON?
JSONL (or NDJSON) has one complete JSON value per line. Standard JSON has one root value, typically an array or object, for the entire file. JSONL is easier to stream and append to; standard JSON is easier to query as a single document.
What if some lines in my JSONL are invalid?
The converter will flag invalid lines. You can choose to skip them or fix them before converting.
Is my data uploaded to a server?
No. The conversion is entirely in your browser using JavaScript.
Can I convert a very large JSONL file?
Browser-based conversion is limited by available memory. For very large files (hundreds of megabytes or more), a command-line tool like jq is more practical: jq -s '.' input.jsonl > output.json
How do I convert JSON back to JSONL?
Use the JSON-to-JSONL converter, which splits a JSON array into one JSON value per line.