CSV JSON Transformer
Advanced CSV ↔ JSON converter with column mapping. Toggle columns on/off, rename JSON keys, and set column types (string, number, boolean). Paste your CSV and configure the mapping before converting. Runs entirely in your browser — your data never leaves your machine.
Column Mapping
| Include | CSV Column | JSON Key | Type |
|---|
Frequently Asked Questions
What makes this CSV to JSON tool 'advanced'?▼
Unlike basic converters, this tool lets you map each column individually: rename the JSON key, toggle a column on or off, and set the type (string, number, boolean). This is useful when your CSV has columns you don't need, headers with spaces or special characters, or numeric columns that are incorrectly treated as strings.
How does the column type setting work?▼
When you set a column to 'number', values are parsed with parseFloat/parseInt. 'boolean' converts 'true', '1', 'yes', 'on' to true and everything else to false. 'string' keeps the value as-is. This lets you get properly typed JSON without post-processing.
Can I convert JSON back to CSV?▼
Yes. Switch to JSON → CSV mode by clicking the direction toggle. Paste a JSON array of objects and get clean CSV with headers from the first object's keys. Nested objects are flattened to a string representation.
What CSV delimiters are supported?▼
The tool auto-detects comma (,), semicolon (;), and tab ( ) delimiters by sampling the first line of your CSV. You can also manually select the delimiter from the dropdown if auto-detection picks the wrong one.
Is there a row limit for CSV conversion?▼
No hard limit — the conversion runs in your browser. Very large files (100k+ rows) may cause brief UI lag since JavaScript is single-threaded. For production data processing, use server-side tools like Python pandas or Node.js csv-parse.
Are my CSV or JSON files uploaded anywhere?▼
No. All processing runs entirely in your browser using vanilla JavaScript. Your data never leaves your machine, making this safe for files containing PII, credentials, or sensitive business data.
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