Convert between CSV and JSON with custom delimiters. 100% local.
This tool runs 100% in your browser. All computation happens locally on your device — your input is never uploaded to any server. Results are for reference only.
CSV is a flat table: one header row names the columns, every following line is one record with the same fields. JSON is a nestable tree: objects can hold objects and arrays, so it can express repeats, nesting and blank fields that a grid cannot. Converting CSV → JSON turns each row into an object keyed by the header; JSON → CSV flattens those objects back into rows. When a JSON field nests deeper, its path becomes part of the column name so nothing is lost.
Three rows × three columns map cleanly to an array of three objects. runtimes, units and modes are straight 1:1 — that is the entire job of the converter, done locally.
The same three contacts, kept as a grid in CSV and as objects in JSON.
To convert CSV to JSON: paste your CSV data or upload a file — the tool parses it and outputs clean JSON with auto-detected headers. Reverse conversion also supported.
FreeToolHub CSV to JSON Converter is a free browser-based tool that converts between CSV and JSON formats, no signup, no upload.
Convert CSV to JSON and back. Auto-detects comma, tab, semicolon delimiters. Handles nested quotes. 100% browser-based, free.
This converter transforms CSV data into JSON arrays and JSON back into CSV, with the delimiter intelligence that real files demand: comma, tab, and semicolon delimiters are auto-detected, which rescues European exports where semicolons separate fields and the decimal comma lives inside them. Quoted fields containing commas, embedded quotes, and newlines parse correctly per RFC 4180, headers become JSON keys, and a type-inference pass turns numeric and boolean-looking fields into real numbers and booleans instead of strings. Conversion runs entirely in the browser, so customer exports and internal reports never upload anywhere.
Developers feed spreadsheet exports into APIs and databases that want JSON, without writing a one-off script every time. Data analysts move report data into visualization and notebook tools that prefer JSON structures. Product managers inspect a CSV a partner sent without opening a spreadsheet app. Anyone working with international exports benefits from the delimiter and decimal-comma handling, and anyone with sensitive lists — customer data, financial exports — gets the privacy of a purely local conversion.
(1) Paste CSV or use the file picker; the delimiter auto-detects, overridable manually if detection guesses wrong. (2) The first row is treated as headers and becomes JSON object keys. (3) Convert to JSON: each row becomes an object, quoted fields unwrap safely, and values that look numeric or boolean convert to native types. (4) In the reverse direction, paste a JSON array of objects; the union of keys forms the header row, values quote as needed, and you choose the output delimiter. Both directions preview instantly and support copy or file download.
CSV looks trivial until values contain the delimiter itself. The RFC 4180 answer is quoting: a field containing a comma wraps in double quotes, and a literal quote inside doubles up as "". Naive parsers that split on every comma shred addresses like "Portland, OR" into two fields; this converter implements the full quoting rule, so embedded commas, quotes, and even newlines inside quoted fields survive round-trips. Regional settings add the second trap: many European locales export semicolon-delimited CSV with comma decimals, so a file from a German Excel build is not broken — it is just speaking a different dialect, which auto-detection handles. When converting back to CSV for a specific consumer, match its dialect deliberately: Excel in the US expects commas, much of the EU expects semicolons, and systems loading via pandas accept either once declared.
It uses a proper CSV parser that respects RFC 4180 quoting rules. Fields wrapped in double quotes can contain commas, newlines, and quote characters (escaped as ""). This handles Excel exports, Google Sheets downloads, and database dumps correctly—unlike simple comma-split approaches that break on embedded commas.
Yes. When converting JSON to CSV, it flattens nested objects using dot notation (e.g., user.address.city becomes a column header). When converting CSV to JSON, you can choose between array-of-objects format or key-value pairs. Auto-detection handles comma, tab, and semicolon delimiters.
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