Convert CSV to JSON and JSON to CSV. Handles nested JSON, custom delimiters, quoted fields, and Excel data.
This tool converts CSV (Comma-Separated Values) files to JSON format and back again — entirely in your browser. Nothing is ever uploaded. You paste your data in, the conversion runs in JavaScript on your device, and you copy or download the result. It's suitable for sensitive data precisely because nothing leaves your machine.
The first row of your CSV is treated as the header and becomes the key names in the JSON output. Each subsequent row becomes one object in the resulting array. Quoted fields containing commas or line breaks are handled correctly.
Paste any JSON array of objects. Each object in the array becomes a row. Column headers are derived from the keys of the first object. If later objects contain additional keys not present in the first row, those fields will be included in the header.
Select a range in Excel or Google Sheets and copy it. The data is copied as tab-separated values. Paste it here and set the delimiter to Tab — the converter handles it identically to CSV.
When converting nested JSON to CSV, enable the "Flatten nested JSON" option. A field like {"address":{"city":"Austin","state":"TX"}} becomes two columns: address.city and address.state.
Not all CSV files use commas. European formats commonly use semicolons. Database exports often use pipes (|). TSV files use tabs. Select your delimiter from the dropdown before converting — or enter a custom character. The converter respects your delimiter choice in both directions.
With "Infer types" enabled, numeric strings like "42" become the number 42 in JSON, and "true"/"false" become JSON booleans. Disable this if your data contains numeric-looking strings that should stay as strings (e.g. ZIP codes or phone numbers).
CSV is a flat, tabular format — every row has the same columns. It opens natively in Excel, Google Sheets, and most database tools. It's the standard for data exports, analytics pipelines, and anything a non-developer needs to read.
JSON is a hierarchical format. It supports nested objects, arrays within arrays, and mixed types. It's the standard for web APIs, configuration files, and data passed between applications. Most modern programming languages have built-in JSON parsers.
You typically need to convert between the two when: you receive data in one format but your destination requires the other. Common scenarios include importing an API response into a spreadsheet, exporting database data for a web app, or moving data between tools with different input requirements.
Paste your CSV into the left panel with "CSV → JSON" mode selected, then click Convert. The first row becomes JSON keys. The result appears on the right — copy it or download as a .json file.
Select "JSON → CSV" mode, paste your JSON array into the left panel, and click Convert. Each object becomes a row. Keys from the first object become column headers.
Yes. Enable "Flatten nested JSON" before converting. Nested objects are expanded into dot-notation columns (e.g. address.city). Arrays within objects are serialized as strings.
Yes. Use the Delimiter dropdown to select Tab (for TSV or Excel copy-paste), semicolon (for European CSV formats), pipe, or enter any custom delimiter character.
Yes. All conversion runs in your browser using JavaScript. Nothing is uploaded. Nothing leaves your device. It's safe to use with sensitive, confidential, or PII data.
Select your cells in Excel and copy (Ctrl+C). Paste into the input panel here, then set the delimiter to Tab. Excel copies data as tab-separated values — the conversion will work correctly.
CSV is a flat tabular format used in spreadsheets. JSON is a hierarchical format used in APIs and applications. CSV is easier to open in Excel; JSON is easier to use in code. This tool converts between the two.