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JSON Lines Converter

Convert between JSON arrays and JSON Lines (JSONL) format. Useful for log files, data pipelines, and streaming JSON. Runs entirely in your browser — your data never leaves your machine.

json jsonl ndjson converter data

Published May 30, 2026

All interactive tools run entirely in your browser. Your data never leaves your device.

How It Works

Paste a JSON array to convert it to JSONL (one JSON object per line), or paste JSONL to combine into a JSON array. JSONL is widely used in logging, data streaming, and machine learning pipelines.

Features

  • JSON to JSONL: convert a JSON array into one-object-per-line format
  • JSONL to JSON: combine JSONL lines into a pretty-printed JSON array
  • Nested objects: handles complex nested structures
  • Mixed types: supports objects, arrays, strings, numbers, booleans, null
  • Line count: shows how many records were processed
  • Round-trip safe: JSON to JSONL to JSON preserves data exactly
  • 5 examples: simple objects, log entries, mixed types, CSV-like data, nested objects
  • Private: runs entirely in the browser — no data transmitted

Use Cases

  • Converting log files between JSON array and JSONL format
  • Preparing data for streaming pipelines (e.g., BigQuery, Elasticsearch)
  • Processing newline-delimited JSON (NDJSON) data
  • Transforming ML training data between formats