JSONL Formatter & Beautifier
Pretty-print and format JSONL (JSON Lines) with configurable indentation. 100% client-side, your data never leaves your browser.
Input JSONL
Drop a .jsonl file here, or click to browse
Supports .jsonl, .ndjson, .json, .txt
Options
Formatted Output
Paste or drop JSONL content to format
How to Format JSONL
JSONL formatting takes each line of a JSONL file, parses it as a JSON object, and re-serializes it with your chosen indentation style. This makes the data much easier to read and debug.
Our formatter works entirely in your browser. No data is uploaded to any server. Simply paste your JSONL text or drag and drop a file, choose your formatting options, and the beautified output appears instantly.
Invalid lines are preserved as-is and reported separately, so your data is never lost. You can also use compact mode to minify each line for smaller file sizes.
What is JSONL Formatting?
JSONL formatting is the process of pretty-printing each JSON object within a JSONL file. While JSONL files typically store each object on a single compact line, formatting expands them with proper indentation, making nested structures visible and the data easier to inspect.
This is especially useful when debugging API responses, reviewing log files, or preparing data for documentation. You can choose between different indentation levels (2 spaces, 4 spaces, or tabs) and optionally sort keys alphabetically for consistent ordering.
Common Use Cases
Debugging API Responses
Format JSONL API logs for easy reading and quick identification of issues in response data.
Code Review
Beautify JSONL config files and datasets for clearer code reviews and pull request diffs.
Log Inspection
Pretty-print JSONL log files to trace application behavior and investigate errors.
Data Documentation
Format JSONL samples for inclusion in documentation, README files, and technical guides.
Frequently Asked Questions
Does formatting change my data?
No. Formatting only changes whitespace and indentation. Your data values, keys, and structure remain exactly the same. The sort keys option reorders keys alphabetically but does not change any values.
What is compact mode?
Compact mode minifies each JSON line by removing all unnecessary whitespace. This is useful for reducing file size when the JSONL file needs to be as small as possible.
Is my data safe?
Yes. All formatting happens locally in your browser. No data is sent to any server. Your JSONL content never leaves your device.
Can I format invalid JSON lines?
Invalid lines cannot be formatted, but they are preserved as-is in the output and reported separately so you can identify and fix them.