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CSV to JSON Converter

Header detection and type inference, automatically.
processes as you type · client-side
Sample
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First row is header
Infer types
⧉ Copy output ⌘C
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Input143 B · paste or drop a file
1 2 3
Output
codetree
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18
[ { "id": "usr_8x42", "name": "Ada Lovelace", "email": "ada@example.com", "active": true, "plan.tier": "pro", "plan.seats": 5 }, { "id": "usr_9k11", "name": "Grace Hopper", "email": "grace@example.com", "active": false, "plan.tier": "free", "plan.seats": 1 } ]
✓ valid (RFC 8259)143 B → 316 B0.0 msLn 1, Col 1UTF-8

About CSV to JSON

The CSV to JSON converter parses comma-separated data into a clean JSON array of objects. It reads the header row for field names, splits each row into values, and can infer types so numbers and booleans come out as real JSON values rather than strings.

Parsing happens in your browser — the CSV is never uploaded — so converting an exported spreadsheet of customers, orders or analytics stays private. It is free, instant and requires no account.

It is the quickest way to turn a spreadsheet export or a database dump into JSON you can feed to an API, load into code, or use as test fixtures.

How it works

Header detection

With the header option on, the first row becomes the object keys and every following row becomes an object. Turn it off and each row is emitted as an array of values instead, which is useful for headerless data.

Type inference

With inference on, values that look like numbers become JSON numbers, true/false become booleans, and empty cells can become null — so 42 is a number, not "42". Turn it off to keep every value as a string, which is safer when leading zeros or ID codes must be preserved.

Quoted values and embedded delimiters

The parser understands the standard CSV quoting rules: fields wrapped in double quotes may contain commas, newlines and escaped quotes, and they are unwrapped correctly so a value like "Smith, Jane" stays a single field.

Whitespace and blank lines

Surrounding whitespace is handled per field and empty trailing lines are ignored, so a stray newline at the end of a file doesn't produce a spurious empty object.

Frequently asked questions

Does the first CSV row have to be a header?

Only if you want named fields. With header detection on, row one supplies the keys; with it off, each row becomes an array of values instead.

Why did my ZIP code lose its leading zero?

Type inference turned it into a number. Turn inference off to keep every value as a string so codes, IDs and numbers with leading zeros are preserved exactly.

Can it handle commas inside a field?

Yes, as long as the field is wrapped in double quotes per the CSV standard. The parser unwraps quoted fields and preserves the commas and newlines inside them.

Is my CSV uploaded anywhere?

No. Parsing runs locally in your browser, so exported spreadsheets with sensitive data never leave your machine.

What delimiter does it expect?

Standard comma-separated values. If your file uses semicolons or tabs, convert or adjust it first — the header detection and quoting rules assume commas.