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NDJSON/JSONL Viewer

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JSONL Input
Paste JSONL content or load a file to get started

What This Tool Does

You can view and validate a JSONL or NDJSON file in the browser without uploading it. The NDJSON/JSONL Viewer parses each line as a separate JSON object entirely on your device, reports invalid lines with line numbers, and renders valid records in a sortable, filterable table. No file ever leaves your machine — there is no server upload.

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This tool is provided as-is for convenience. Output should be verified before use in any production or critical context.

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Browser workflow

Runs instantly in the browser with private local processing and copy/export-ready output.

Browser Workflow

This tool is optimized for instant in-browser execution with local data handling. Run it here and copy/export the output directly.

/jsonl-viewer/

For automation planning, fetch the canonical contract at /api/tool/jsonl-viewer.json.

How to Use NDJSON/JSONL Viewer

  1. 1

    Load JSONL/NDJSON data

    Paste your JSONL data (one JSON object per line) or upload a .jsonl/.ndjson file. The viewer auto-detects the format.

  2. 2

    Convert to interactive table

    The tool parses each line and renders an interactive table where each row is one JSON object and columns are detected from keys.

  3. 3

    Filter and search

    Use the filter panel to search by column values, regex patterns, or range queries (e.g., timestamp > 2026-01-01). Results update in real-time.

  4. 4

    Sort and export

    Click column headers to sort by any field. Export filtered results as CSV, JSON array, or back to JSONL format.

Frequently Asked Questions

What is NDJSON/JSONL Viewer?
NDJSON/JSONL Viewer parses and displays newline-delimited JSON data in an interactive table format. It supports filtering, sorting, and exporting, making it ideal for exploring log files and event streams.
How do I use NDJSON/JSONL Viewer?
Paste your JSONL or NDJSON data into the input field. The tool parses each line as a separate JSON object and displays them in a sortable, filterable table. You can search, sort by any column, and export results.
Does NDJSON/JSONL Viewer store or send my data?
No. All processing happens entirely in your browser. Your log data never leaves your device — nothing is sent to any server.
What is the difference between JSONL and NDJSON?
JSONL (JSON Lines) and NDJSON (Newline Delimited JSON) are the same format — one JSON object per line, separated by newlines. Both are commonly used for log files, data streaming, and bulk data processing.

How do I view and validate a large JSONL file in the browser without uploading it?

Open the viewer, then paste your JSONL content or load a local .jsonl, .ndjson, or .json file. The file is read with the browser's FileReader API and parsed line by line in the page itself, so nothing is transmitted to a server. Because there is no upload step, the practical size limit is your browser's memory, not a network quota.

Step by step

  1. Paste JSONL text into the input, or use the file picker to open a local file — it is read locally, never uploaded.
  2. Each line is parsed as an independent JSON object. Invalid lines are listed with their line number and parse error, so you can fix the exact offending records.
  3. Lines that parse but are not JSON objects (bare arrays or primitives) are flagged separately, since JSONL tooling expects one object per line.
  4. Browse valid records in the table: sort by any column, filter per column, or search across all fields.
  5. Export the filtered result when you are done.

What makes a JSONL file valid?

Rule Detail
One JSON value per line Every line must be a complete, self-contained JSON document. In practice each line is an object.
Newline separated Records are separated by newline characters. There is no enclosing array and no commas between records.
No trailing commas or comments Each line must be strict JSON. Trailing commas, single quotes, and comments fail per-line validation.
Blank lines are skipped Empty lines are ignored by the parser rather than reported as errors.

Is JSONL the same as NDJSON?

Yes. JSONL (JSON Lines) and NDJSON (Newline Delimited JSON) describe the same format: one JSON object per line. It is the standard shape for log files, event streams, LLM fine-tuning datasets, and bulk exports, because each record can be read, validated, and streamed independently.

Why does no-upload matter for log data?

JSONL files are usually production logs, event exports, or training data — content that often contains user identifiers, prompts, or internal system details. A client-side viewer removes the data-handling question entirely: the parsing code runs in your browser tab, and closing the tab discards everything.