FileSwift
Home/CSV Converter
Free · runs in your browser · secure offline conversion

Convert CSV & JSON,
privately.

Switch between spreadsheet data and developer formats instantly. Upload or paste your rows to parse them locally. Zero uploads, zero databases, and 100% compliant with enterprise data protection guidelines.

Input size
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Output size
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Format mode
🛡️ Private Local Conversion: Your data never leaves your device and is never uploaded or saved. Disconnect your internet to test—this page works 100% offline.

CSV / JSON Data Converter

Drag and drop a .csv or .json file, or paste your raw text in the input box below.

Drop CSV or JSON file here, or click to browse
Supports .csv, .json, and .txt files
Input (CSV or JSON text)
Converted Output

Common questions

How does the auto-detection work?

Pasted text starting with [ or { is treated as JSON — including JSON Lines (one JSON object per line, a common format for logs and API exports). Everything else is treated as CSV, with the delimiter auto-detected unless you set it manually above.

What happens if some rows in my CSV don't match?

Rows with too few or too many columns, or an unterminated quote, don't block the rest of the file — they're converted as best as possible and listed in a notes panel so you know exactly which rows to check.

What happens with nested JSON objects or arrays?

Nested objects are flattened into dot-notation columns (e.g. address.city). Arrays are stored as JSON text in a single cell. Records with different fields are combined into one column set, so no data is silently dropped.

Can I convert offline?

Yes. The parsing engine is completely client-side. You can completely disconnect your internet, load your files, convert, and download without any network requests.

Understanding CSV & JSON Formats

Spreadsheets and modern databases use different systems to organize data. Comma-Separated Values (CSV) is a simple text format where each line represents a row, and fields are separated by characters like commas, tabs, or semicolons. It is the universal format for exporting lists from software like Microsoft Excel, Google Sheets, or SQL databases.

On the other hand, JSON (JavaScript Object Notation) is a structured nested format preferred by developers for building websites, APIs, and modern apps. Converting a CSV sheet to JSON translates flat rows into an array of structured JSON objects. This allows software platforms to parse and consume spreadsheet records programmatically.

FileSwift makes this translation seamless. We handle quotes, special character delimiters, and automatically parse nested parent-child hierarchies into clean arrays. Since everything happens inside your browser's local sandbox, it is highly secure for handling corporate database dumps, customer emails, and private financial logs.