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View JSONL as a Sortable Table View JSONL (JSON Lines) data as a formatted, sortable table.

JSON Lines Viewer illustration
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JSON Lines Viewer

View JSONL (JSON Lines) data as a formatted, sortable table.

1

Paste JSONL data

Paste JSON Lines data (one JSON object per line).

2

View as table

Objects are rendered as sortable table rows.

3

Sort and explore

Click column headers to sort by any field.

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What Is JSON Lines Viewer?

JSON Lines Viewer renders JSONL (JSON Lines / Newline-Delimited JSON) data as a formatted, sortable table. It is a format where each line is a valid JSON object, commonly used for log files, streaming data, and large datasets. This viewer parses each line, extracts all unique keys as column headers, and renders each object as a table row. Nested values are displayed as JSON strings. Columns are sortable with automatic numeric detection.

Why Use JSON Lines Viewer?

  • Renders JSONL as a clean table instead of raw text.
  • Collects all unique keys for complete column coverage.
  • Sortable columns with numeric auto-detection.
  • Validates each line and reports parsing errors with line numbers.

Common Use Cases

Log Analysis

View structured log files (commonly in JSONL format) in a readable table.

Streaming Data

Inspect JSONL data streams from Kafka, Kinesis, or other streaming platforms.

Data Pipelines

Review JSONL output from data processing pipelines and ETL jobs.

Machine Learning

View JSONL training data or model output in tabular format.

Technical Guide

The viewer splits input by newlines and parses each non-empty line as JSON using JSON.parse(). Each line must be a valid JSON object (not array or primitive). If parsing fails, an error message identifies the problematic line number.

All unique keys across all objects are collected into a header set, ensuring the table includes all possible columns. Objects missing certain keys display empty cells for those columns.

Sorting works by converting values to strings and comparing them. Numeric values are detected and sorted numerically. Nested objects and arrays are displayed as their JSON string representation in table cells.

Tips & Best Practices

  • 1
    Each line must be a valid JSON object — arrays and primitives are not supported.
  • 2
    Nested objects are displayed as JSON strings in table cells.
  • 3
    Invalid lines show error messages with line numbers for easy debugging.
  • 4
    All unique keys are collected as columns — objects don't need identical keys.

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Frequently Asked Questions

Q What is JSON Lines format?
JSON Lines (JSONL/NDJSON) is a format where each line is a complete, valid JSON value, typically a JSON object.
Q How are nested values displayed?
Nested objects and arrays are shown as their JSON string representation in the table cell.
Q What if lines have different keys?
All unique keys are collected. Missing keys in individual objects show as empty cells.
Q Can it handle large files?
Performance depends on browser memory. Thousands of lines typically work well.
Q How are errors reported?
If a line fails to parse as JSON, an error message shows the line number and the parsing error.

About This Tool

JSON Lines Viewer is a free online tool by FreeToolkit.ai. All processing happens directly in your browser — your data never leaves your device. No registration or installation required.