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  3. JSONL Formatter

JSONL Dataset Formatter

Convert data to JSONL format for AI fine-tuning

Format Examples

{"messages":[{"role":"user","content":"..."},{"role":"assistant","content":"..."}]}

Related Tools

  • JSON Formatter - validate individual JSON objects
  • CSV to JSON - convert tabular data first
  • Token Counter - estimate training costs
  • JSON Schema Builder - define output structure

How to Use JSONL Formatter

  1. Paste your data

    Enter JSON array data or individual JSON objects to convert.

  2. Convert to JSONL

    See your data converted to JSON Lines format (one object per line).

  3. Download or copy

    Copy the JSONL output or download it as a .jsonl file.

Frequently Asked Questions

Is the JSONL Formatter free to use?
Yes, the JSONL Formatter is completely free with no limitations. Convert and format as much data as you need for AI fine-tuning without registration.
Is my training data private?
Yes, all JSONL formatting happens locally in your browser. Your training data, prompts, and completions are never sent to any server, keeping your fine-tuning datasets confidential.
What is JSONL format?
JSONL (JSON Lines) is a format where each line is a valid JSON object. It is the standard format for AI fine-tuning datasets, log files, and streaming data because it allows for easy line-by-line processing.
What AI platforms use JSONL?
JSONL is used by OpenAI for fine-tuning GPT models, by Anthropic for Claude training, and by many other AI platforms. The tool helps format your data to match each platform's expected structure.