JSON to CSV Converter — Free Online JSON→CSV Tool

How to use

1. Paste or type your JSON into the left box — a sample is already loaded on first visit.
2. The right side updates live as you type (debounced ~250 ms), or press the Convert button.
3. Use Copy to copy the CSV to your clipboard, or Download .csv to save it locally.
4. The output uses CRLF line endings (RFC 4180), so it opens correctly in Excel, Google Sheets and Numbers.
5. The left input is remembered in your browser, so you can come back and keep editing.

What is it

JSON and CSV are two sides of the same coin: JSON is a nested, typed data format used by APIs and programs, while CSV is a flat, rectangular table that spreadsheets understand natively. This tool parses your JSON with the built-in JSON.parse and rebuilds it as CSV with the open-source papaparse library. An array of objects becomes a table with a header row, a single object becomes a one-row table, and scalar values become a single column. Nested objects are flattened into dot-notation column names (user.name) and nested arrays are stored as JSON text — so even messy data can land in a spreadsheet without losing information.

Notes & fun facts

CSV is older than almost every piece of software you use. In the 1960s, before databases and the internet, data lived on punched cards, and early Fortran and COBOL programs routinely exchanged records using comma-separated values. The format had no official standard for decades — every program had its own quirks about quoting, escaping and line endings. It was not until October 2005 that the Internet Engineering Task Force published RFC 4180, formally defining CSV with its MIME type text/csv. Today CSV is the lingua franca of data: spreadsheet exports, database dumps, banking statements, Kaggle datasets and pandas DataFrames all speak CSV. It survives because it is brutally simple — plain text, one row per line, columns separated by commas — which makes it readable by every language and every tool, from Excel to a shell script. JSON, born in the early 2000s out of JavaScript, describes nested, typed structures that CSV cannot express directly. This tool is the bridge between the two worlds: it flattens your JSON into the rectangular shape spreadsheets love, so a few lines of configuration data can become a table you can filter, sort and chart.

Origin & history

CSV's roots go back to the punched-card era of the 1950s and 1960s, when record-oriented data storage made fixed or comma-separated fields natural. In 1972, the FORTRAN manual "A FORTRAN Primer" by E. I. Organick described comma-separated output for data exchange, and the concept spread from mainframe culture into the personal-computer era with spreadsheet pioneers like VisiCalc (1979) and Lotus 1-2-3 (1983). Microsoft Excel adopted CSV for import and export, and for decades "save as CSV" has been the universal escape hatch for moving data between applications. RFC 4180, published in October 2005 by the IETF, finally standardized the format: CRLF line endings, an optional header row, and quoting rules for commas and newlines. Meanwhile JSON (JavaScript Object Notation) was formalized by Douglas Crockford around 2001–2006 and standardized as ECMA-404 in 2013 — it is the default for web APIs but cannot represent rectangular tables efficiently. The papaparse library used by this tool was open-sourced in the mid-2010s under the MIT license: it is one of the most widely used CSV libraries in the JavaScript ecosystem, zero-dependency, ESM-friendly, and serializes JavaScript objects to CSV entirely in the browser with no server round-trip.

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