CSV ↔ JSON Converter — Types, Delimiters & Local
Convert CSV to JSON or JSON to CSV in your browser. Steps: pick a direction, paste or upload, set the delimiter and header, then copy or download. Handles quoted fields with commas, semicolons and tabs, and flattens nested JSON to columns. Example: turn a product sheet (sku, title, price) into a JSON array — data stays local.
How it works
Choose CSV → JSON or JSON → CSV. Parsing and serialization run with Papa Parse in this tab. For CSV, pick a delimiter (or auto-detect), say whether the first row is a header, and optionally infer numeric/boolean types. For JSON, nested objects flatten to dot-path columns and the column set is the union of all record keys.
Rules you should expect
What to expect when you convert: how cell types are handled, which delimiters and quoting apply, and how nested JSON maps to columns.
- Types: CSV cells are strings by default. Turn on “Infer types” to get numbers/booleans — but note 007 becomes 7 and long digit strings may lose precision, so keep it off for SKUs, ZIPs and phone numbers.
- Delimiters: comma, semicolon (common in EU Excel) and tab (TSV) are supported; auto-detect guesses from the text. Fields containing the delimiter, quotes or line breaks are wrapped in double quotes per RFC 4180.
- JSON → CSV: objects flatten with dot paths (dim.w, dim.h); arrays are written as a JSON string in one cell; columns are the union of all keys, with missing values left blank.
- Privacy: your paste and files are not uploaded. Fetching Papa Parse from a CDN only downloads library code, not your data.
Example
CSV `sku,title,price` with row `A-001,"Chair, oak",129.9` becomes JSON `{"sku":"A-001","title":"Chair, oak","price":"129.9"}` (types off keeps price as text; turn typing on to get the number 129.9). Reverse: `[{"sku":"A-001","dim":{"w":40,"h":90}}]` becomes header `sku,dim.w,dim.h` with row `A-001,40,90`.
Good fits
- E-commerce: turn an exported product sheet (sku, title, price) into a JSON array for a store or marketplace API.
- Developers: reshape an API/JSON payload into CSV for spreadsheets, reconciliation or hand-off.
- Data / ops: bridge report or event CSV (comma, semicolon or TSV) into JSON for a pipeline, with commas and line breaks safely quoted.
Frequently asked questions
Will my numbers, leading zeros and IDs stay intact?
By default every CSV cell is kept as text, so 007 and long IDs are preserved. If you turn on “Infer types”, numeric-looking values become numbers — 007 becomes 7 and very long digit strings can lose precision. Keep typing off for SKUs, ZIP codes and phone numbers.
Can it handle semicolons or tabs, not just commas?
Yes. Choose comma, semicolon or tab, or leave it on auto-detect and Papa Parse guesses from the text. Semicolons are common in European Excel exports; tabs mean TSV.
How are fields with commas, quotes or line breaks handled?
They are wrapped in double quotes and inner quotes are doubled, following RFC 4180. So a title like Chair, oak stays in one field instead of splitting into two columns.
How does nested JSON become CSV columns?
Objects are flattened to dot-path columns (dim.w, dim.h). Arrays are written as a JSON string in a single cell. Columns are the union of every record’s keys, and records missing a key get a blank cell.
Does my data leave the browser?
No. Parsing stays in this tab, and files you pick are read locally. A CDN may serve Papa Parse; that request downloads code only — it is not an upload of your CSV or JSON.