Convert JSON to CSV Online — Nested Objects Flattened, No Upload

Which JSON works

An array of objects: [{"id":1,"name":"Ava"}, …]
An API response wrapping the array in a data, rows, items, records or results key — it's found automatically.
JSON Lines / NDJSON: one object per line (.jsonl, .ndjson), typical of logs and data exports.

How nested data is flattened

Each nested field becomes its own column, named after its path, and arrays are kept as JSON text in a single cell:

{"id": 7, "address": {"city": "Lyon", "zip": "69001"}, "tags": ["a", "b"]}

becomes the columns id, address_city, address_zip and tags (containing ["a","b"]). Objects missing a field simply get an empty cell, and values such as zip codes or phone numbers keep their leading zeros.

The column names work directly in queries: SELECT address_city, COUNT(*) FROM data GROUP BY address_city;

Excel users

If your Excel expects semicolons (common with French, German or Spanish regional settings), download with CSV for Excel (;): accents, separators and decimal commas will be right when you double-click the file.

Other free CSV tools

Open a CSV too big for ExcelMillions of rows, hundreds of MB. No 1,048,576-row limit. CSV viewerLook inside any CSV without Excel. Private and instant. Remove duplicate rowsDeduplicate a CSV in one click, then download it clean. CSV to JSONConvert a CSV into a JSON array of objects, typed numbers included. Semicolon ⇄ comma CSVFix Excel's semicolon CSVs, or make one Excel will open. Count rows in a CSVExact row count of any CSV, even a huge one, in seconds. Filter a CSVKeep only the rows you need and download them. Column summaryFilled, distinct, min and max for every column at once. Query CSV with SQLReal SQLite on your file: GROUP BY, JOINs, window functions.

Frequently asked questions

My JSON is one big object, not an array. Will it work?

Yes: a single object becomes a single row, and if the object contains an array under data, rows, items, records or results, that array is used.

Is there a size limit for JSON?

JSON has to be read in one piece, so it uses more memory than CSV. Files up to a couple of hundred MB work on a normal computer; JSON Lines is lighter.

Is my data sent anywhere?

No. The conversion runs entirely in your browser tab.