csv to json converter
typetools
instant, client-side type converter • 0ms network latency
[
{
"id": 101,
"username": "alex_dev",
"email": "[email protected]",
"role": "admin",
"isActive": true,
"score": 98.4
},
{
"id": 102,
"username": "sam_ops",
"email": "[email protected]",
"role": "editor",
"isActive": true,
"score": 91
},
{
"id": 103,
"username": "taylor_qa",
"email": "[email protected]",
"role": "viewer",
"isActive": false,
"score": 84.5
}
]step-by-step integration guide
technical specification differences & end-to-end conversion workflow
Why RFC 4180 CSV Parsing Cannot Be Done with String.split(',')
Comma-Separated Values (CSV), standardized under RFC 4180, is a flat tabular format where records are delimited by line breaks (CRLF or LF) and fields are separated by commas (or tabs/semicolons in TSV/DSV variants). However, RFC 4180 permits fields to contain literal commas, embedded line breaks, and double-quote characters provided the field is enclosed in double quotes ("..."), with interior double quotes escaped by doubling them (""). A naive row.split(',') implementation corrupts any dataset containing currency formatting, street addresses, or multi-line user comments. Moreover, CSV is completely untyped at the lexical level—every cell is raw text, whereas JSON distinguishes between numbers, booleans, null, arrays, and strings.
Finite State Machine Tokenization and Dynamic Type Promotion
Our CSV-to-JSON engine processes tabular input using a character-by-character Deterministic Finite Automaton (DFA) lexer inside a Web Worker. The state machine tracks whether the cursor is currently inside an unquoted field, inside a quoted string literal, or at an escaped quote boundary, ensuring embedded newlines and commas inside quotes are preserved intact. The first row is extracted as the normalized property header vector. As subsequent rows are mapped into JSON objects, an optional type-inference pass inspects each cell: unquoted numeric strings within IEEE 754 safe integer limits are cast to JSON numbers, true/false literals are cast to booleans, empty unquoted cells are mapped to null, and leading-zero strings (such as ZIP codes "02115" or credit card prefixes) are preserved as strings to prevent numeric truncation.
frequently asked questions
common developer questions answered
q:Does the CSV parser preserve leading zeros in ZIP codes and phone numbers?
Yes. Our type inference engine detects leading zero patterns (like 0042 or 07123) and keeps them as JSON string literals rather than coercing them into octal or stripped integers.
q:How are commas and line breaks inside quoted CSV cells handled?
The RFC 4180 state-machine lexer tracks quote boundaries rather than splitting on raw newlines or commas, so multi-line text and commas inside double quotes are accurately parsed into a single JSON string property.
q:Can I convert TSV (Tab-Separated) or semicolon-delimited European CSV files?
Yes. The lexer automatically inspects the header row to detect comma (,), tab (\t), pipe (|), or semicolon (;) delimiters before constructing the JSON object array.