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CSV to JSON Converter Convert CSV data to JSON array format instantly in your browser.

CSV to JSON illustration
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CSV to JSON

Convert CSV data to JSON array format instantly in your browser.

1

Paste CSV data

Paste your CSV content into the input area. The first row should contain column headers.

2

View JSON output

The JSON output appears instantly in the right panel as a formatted array of objects.

3

Copy or download

Use the Copy button to copy the JSON to your clipboard or download it as a file.

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What Is CSV to JSON?

CSV to JSON is a data conversion tool that transforms comma-separated values into JavaScript Object Notation format. CSV (Comma-Separated Values) is one of the most common formats for tabular data — used by spreadsheets, databases, and data export tools. JSON (JavaScript Object Notation) is the dominant format for web APIs, configuration files, and modern applications. This converter takes your CSV input, uses the first row as object keys, and maps each subsequent row into a JSON object within an array. It properly handles edge cases like quoted fields containing commas, escaped double-quotes, empty fields, and multiline values. The conversion runs entirely in your browser, meaning your data never leaves your machine — ideal for sensitive information.

Why Use CSV to JSON?

  • Instant real-time conversion as you paste — no submit button needed.
  • Handles complex CSV edge cases: quoted fields, commas inside values, escaped quotes.
  • Runs entirely in your browser — your data never touches a server.
  • Clean, properly indented JSON output ready for APIs and applications.

Common Use Cases

API Development

Convert CSV exports from databases or spreadsheets into JSON for REST API payloads and testing.

Data Migration

Transform CSV data dumps into JSON format for importing into NoSQL databases like MongoDB.

Web Development

Convert spreadsheet data into JSON for use in frontend applications and JavaScript projects.

Data Analysis

Prepare CSV datasets as JSON for processing with JavaScript-based data visualization libraries.

Technical Guide

Our CSV parser implements RFC 4180 compliance with extensions for real-world data. The parser processes input character by character, maintaining state for quoted fields. When a double-quote character is encountered, the parser enters "quoted mode" where commas and newlines are treated as literal characters rather than delimiters. Escaped quotes (two consecutive double quotes) are collapsed into a single quote character.

The first row of the CSV is always treated as the header row, providing the keys for each JSON object. Each subsequent row becomes a JSON object where keys correspond to the header values and values are the cell contents. Empty cells map to empty strings.

The output JSON is formatted with 2-space indentation for readability. All values are output as strings since CSV has no native type system. If you need numeric or boolean types, you can post-process the JSON with a JSON formatter or code.

Performance considerations: The parser operates in O(n) time complexity where n is the input length. For very large CSV files (>10MB), consider using a dedicated server-side tool.

Tips & Best Practices

  • 1
    Ensure your first row contains meaningful column headers — these become the JSON object keys.
  • 2
    If your CSV uses semicolons or tabs as delimiters, replace them with commas first using find-and-replace.
  • 3
    For CSV files with special characters, make sure fields are properly quoted with double quotes.
  • 4
    Large files may take a moment to process — the conversion happens entirely in your browser memory.

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Frequently Asked Questions

Q Does the first row need to be headers?
Yes, the converter treats the first row as column headers which become the JSON object keys. Without headers, the output would lack meaningful key names.
Q Can it handle commas inside fields?
Yes. Fields containing commas should be wrapped in double quotes (e.g., "New York, NY") and the parser will handle them correctly.
Q What happens with empty cells?
Empty cells are converted to empty strings ("") in the JSON output.
Q Is there a file size limit?
Since processing happens in your browser, the limit depends on your device memory. Files up to several MB work well. For very large files, consider using a server-side tool.
Q Is my data secure?
Yes. All processing happens locally in your browser. No data is sent to any server.

About This Tool

CSV to JSON 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.