csv2json

Convert between CSV and JSON in both directions, with automatic type inference and a proper RFC 4180 parser (quoted fields, escaped quotes, embedded newlines). Zero dependencies.

The companion to csv-peek (which previews CSVs). Unlike csvkit (Python) or paste-it-here websites, this runs locally and never uploads your data.

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Install

npm install -g csv2json

Or without installing:

npx csv2json data.csv

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Usage

csv2json users.csv                    # CSV → JSON on stdout
csv2json users.csv -o users.json      # CSV → JSON file
csv2json users.json -o users.csv      # JSON → CSV
csv2json data.tsv -d tab              # Tab-separated input
cat export.csv | csv2json - --compact # From stdin, single-line JSON

Direction is inferred from the file extension (or the -o target), and falls back to sniffing the content. Force it with --from csv|json.

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Example

users.csv:

id,name,active,score
1,Alice,true,9.5
2,Bob,false,7

csv2json users.csv:

[
  { "id": 1, "name": "Alice", "active": true, "score": 9.5 },
  { "id": 2, "name": "Bob", "active": false, "score": 7 }
]

Note that 1→number, true→boolean, 9.5→float automatically. Disable with --no-type.

Reverse it — csv2json users.json -o users.csv — and you get the CSV back.

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Type Inference

CSV value	JSON value
42	42 (number)
3.14	3.14 (number)
true / false	boolean
null	null
empty cell	"" (or null with --empty-as-null)
anything else	string

Turn it off with --no-type to keep every value a string.

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Options

Flag	Description
--from <csv|json>	Force input format (for stdin / odd extensions)
-o, --out <file>	Write to a file (format from its extension)
-d, --delimiter <d>	, ; | or tab (default: auto-detect)
--no-header	CSV has no header → arrays of values
--no-type	Keep all values as strings
--empty-as-null	Empty CSV cells become null
--skip-empty	Omit empty cells from JSON objects
--pretty / --compact	JSON formatting (pretty is default)

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Nested Values

When converting JSON → CSV, nested objects/arrays in a cell are serialized as JSON strings (and properly quoted). The header row is the union of all keys across every record, in first-seen order.

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License

MIT

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Keywords

csv to json · json to csv · convert csv · csv json converter · csvkit alternative · rfc 4180 · parse csv · tsv to json · zero dependencies · cli

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Built to solve, shared to help — Rushabh Shah 🛠️✨

_{One of 40+ zero-dependency developer CLI tools — no node_modules, ever.}