FreeJSONtoCSV

JSON to CSV Converter.

Convert structured JSON documents or JSONLines lists into flat CSV sheets. Automatic object flattening, custom delimiter selection, and configurable array formatting.

100% Client-Side Safe
• Your data is processed locally in your browser and never uploaded.

Input JSON

Output CSV

Conversion Metrics

Records-
Fields / Cols-
Speed-
Technical Guide

JSON to CSV Developer Reference.

FreeJSONtoCSV provides a secure, client-side utility to parse JavaScript Object Notation (JSON) hierarchical structures and compile them into tabular Comma-Separated Values (CSV) files. By delegating all parsing operations in-memory to background Web Workers, your data never leaves your machine—ensuring 100% security for sensitive datasets.

What is JSON (RFC 8259)?

JSON is a text-based, language-independent syntax for representing nested data structures, keys, and values. It is widely used in API payloads and database storage.

What is CSV (RFC 4180)?

CSV represents tabular data where rows are delimited by newlines and column cells are delimited by commas, semicolons, or tabs. It is the standard format for spreadsheet engines like Excel.

How to Convert JSON to CSV:

  1. Input Data: Paste your raw JSON array/object or drag-and-drop a .json/.jsonl file directly into the input editor.
  2. Configure Options: Toggle nested object flattening (to convert properties like user.name to columns) and customize delimiters (comma, tab, semicolon).
  3. Download or Copy: The output CSV sheet is compiled instantly. Click Download CSV to save the file locally, or copy the values to clipboard.

Nesting & Dot-Notation Flattening

Relational databases and spreadsheets cannot handle nested JSON hierarchies natively. Our parser maps child properties (e.g. {"profile": {"email": "john@example.com"}}) into flat tabular headers using dot-notation (profile.email) automatically, preserving structural integrity. For a deep-dive on converting root arrays, flat lists, and object arrays, read our developer guide on JSON Array to CSV.

Common Mistakes

  • Mismatched JSON syntax: Missing quotes or trailing commas in arrays will trigger syntax errors. Validate your input via the JSON Validator first.
  • Excel character corruption: Microsoft Excel may strip leading zeroes or misformat phone numbers in raw CSV imports. Use our CSV Viewer to inspect the output exactly as compiled.

Technical Limitations

  • Local Memory Boundary: Because conversion runs 100% locally in-memory, files larger than 100MB may hit browser thread memory caps. For larger files, command-line utilities like jq are recommended.
Conversion Example
// Input JSON
[
  {
    "id": 1,
    "user": { "name": "Alice" },
    "role": "Admin"
  }
]
// Flattened CSV Output
id,user.name,role
1,Alice,Admin
FAQ

Frequently asked questions.

Can I convert JSON to CSV?
Yes, you can easily convert JSON to CSV. Our online [JSON to CSV Converter](/json-to-csv/) allows you to copy-paste your JSON structure or upload a .json or .jsonl file to instantly generate and download a clean CSV sheet. The conversion happens entirely locally in your browser, guaranteeing 100% privacy.
How do I convert JSON to Excel?
You can convert JSON to Excel by first converting it to a CSV file using our [JSON to CSV Converter](/json-to-csv/), and then opening that CSV in Microsoft Excel. Alternatively, you can use Excel's built-in Power Query tool (Data > Get Data > From File > From JSON) to import JSON files directly.
How to pass JSON in CSV?
To store complex or nested JSON data inside a flat CSV column, you must serialize (stringify) the JSON object or array into a string, escape any double quotes by doubling them (e.g., ""value""), and enclose the entire field in quotes. Our [JSON to CSV Converter](/json-to-csv/) can also automatically flatten nested JSON fields into flat columns using dot-notation (e.g., user.name).
Is CSV a JSON file?
No, CSV (Comma-Separated Values) and JSON (JavaScript Object Notation) are completely different file formats. CSV represents structured tabular data in rows and columns. JSON is a hierarchical, key-value data format. You can convert between them instantly using our [CSV to JSON Converter](/csv-to-json/) and [JSON to CSV Converter](/json-to-csv/).
How do I create my own JSON file?
You can create your own JSON file by writing structured JSON text in any text editor and saving the file with a .json extension. The text must follow valid JSON syntax rules. To check your syntax, use our [JSON Validator](/json-validator/).
How accurate is the converter?
Our converter is highly accurate. It correctly handles complex structures while automatically inferring appropriate data types. To ensure structural integrity, you can validate your files using the [JSON Validator](/json-validator/) and [CSV Validator](/csv-validator/).
How to convert JSON to CSV using Excel?
To convert JSON to CSV directly in Excel, go to the Data tab, click Get Data > From File > From JSON. Import your JSON file, click Convert to Table in the Power Query Editor. Alternatively, you can use our online [JSON to CSV Converter](/json-to-csv/) for a much simpler process.
Are there any limitations to the converter?
Since the converter runs 100% in your browser for privacy, it uses your local system's memory. While we use Web Workers to process files up to 100MB, extremely large files are better suited for command-line utilities. You can inspect parsed tree nodes in our [JSON Viewer](/json-viewer/).
How do I convert JSON to CSV using Python?
To convert JSON to CSV in Python, you can use the built-in json and csv modules, or the pandas library. In Pandas, read the JSON string or file using df = pd.read_json('file.json') and export it to CSV using df.to_csv('file.csv', index=False).
How can I convert JSON to CSV using jq?
With the command-line tool jq, you can use the raw output filter to map object values into an array and feed it to the @csv formatter. For example: jq -r '.[] | [ .id, .name, .email ] | @csv' input.json > output.csv.