CSV to JSON Converter

The CSV to JSON Converter transforms CSV (Comma-Separated Values) data into JSON format — arrays of objects keyed by column headers. Supports standard comma delimiters, semicolon (European CSV), tab (TSV), pipe, and custom delimiters. Handles quoted fields with embedded commas, newlines, and escape characters per RFC 4180. Bidirectional: convert CSV → JSON or JSON → CSV with one click. Works with spreadsheet exports (Excel, Google Sheets, Numbers), database dumps, API data exports, and log files. Every conversion is instant and client-side — your data (which may include customer info, product catalogs, sales figures) never leaves your device.

CSV is the lingua franca of tabular data: Excel, Google Sheets, databases, financial systems, and virtually every business application export CSV. JSON is the dominant format for APIs and modern data pipelines. Converting between them is a daily task for data engineers, analysts, and developers. This tool handles tricky edge cases — international CSV (semicolons), multi-line cells, escaped quotes, inconsistent columns — and produces clean JSON ready to POST to an API or store in a database.

CSV is defined by RFC 4180 (2005). A CSV file has:

- Records separated by CRLF (line breaks).
- Fields separated by commas (or another delimiter).
- Fields containing commas, newlines, or double-quotes must be enclosed in double quotes.
- Double quotes within quoted fields escaped as two double quotes ("").
- Optional header row as the first record, defining column names.

Example CSV:
``csv
name,email,age
Jane Doe,jane@example.com,36
"O'Brien, Patrick",patrick@example.com,42
"Wrote ""Hello""",sample@example.com,28
``

Converts to JSON:
``json
[
{"name": "Jane Doe", "email": "jane@example.com", "age": "36"},
{"name": "O'Brien, Patrick", "email": "patrick@example.com", "age": "42"},
{"name": "Wrote \\"Hello\\"", "email": "sample@example.com", "age": "28"}
]
``

CSV variants:

- Standard CSV (RFC 4180) — comma-separated, CRLF line endings.
- European CSV — semicolon-separated (because comma is the decimal separator in many European locales: 3,14).
- TSV (Tab-Separated Values) — tab delimiter, commonly used for data transfer where quoted fields are avoided.
- Pipe-delimited — rare, used by some legacy systems.
- Space-delimited — some Unix tools; ambiguous and fragile.

Output modes:

- Array of objects (default): [{name: "Jane", age: 36}, ...] — keys from first row (headers).
- Array of arrays: [["Jane", 36], ["Bob", 42]] — no keys, positional data.
- Nested objects: If column names use dot notation (address.street), output nests the structure.

Type inference:

By default, all values are strings ("36" not 36). Optional type inference:

- Numbers: 36 → 36 (int), 3.14 → 3.14 (float)
- Booleans: true, false, TRUE, FALSE
- Null: empty cells → null
- Dates: ISO 8601 strings stay as strings (parsing dates is error-prone)

Edge cases handled:

- Quoted fields with commas: "O'Brien, Patrick" → "O'Brien, Patrick" (comma preserved)
- Embedded quotes: "Wrote ""Hello""" → "Wrote \\"Hello\\""
- Multi-line fields: Fields with newlines must be quoted. Preserved in JSON output.
- Empty fields: a,,b → empty string "" or null depending on settings.
- Inconsistent columns: Some rows have more/fewer fields than headers. Options to truncate, pad with null, or reject.

BOM handling:

Files saved by Excel often have a Byte Order Mark (\\uFEFF) at the start. Most CSV parsers handle this automatically; legacy tools may show weird characters. This tool strips BOM by default.

CSV vs JSON: CSV is flat (no nesting), tabular, compact, universally readable in spreadsheets. JSON supports nesting, arrays, mixed types, more expressive but harder to visualize. Use CSV for simple 2D data, JSON for structured/nested data.

CSV vs Excel (.xlsx): CSV is plain text, opens anywhere. Excel is binary format requiring Excel or compatible apps. Excel supports formulas, multiple sheets, formatting. CSV is ONE sheet of values only. Convert Excel to CSV before JSON conversion.

CSV vs TSV: TSV uses tabs instead of commas. Simpler because tabs rarely appear in data (no escaping needed). Common in scientific data, database dumps. CSV is more widely supported.

CSV vs Parquet/Avro: Parquet and Avro are columnar binary formats used in big data (Hadoop, Spark). Smaller and faster for analytics. CSV is readable; Parquet/Avro requires specialized tools. Use CSV for small-medium datasets, Parquet for GB+ datasets.

JSON vs NDJSON (JSONL): NDJSON (Newline-Delimited JSON, .ndjson, .jsonl) stores one JSON object per line — ideal for streaming and log files. Standard JSON stores an array. NDJSON is easier to process line-by-line and append to.

Standard CSV vs European CSV: European countries use comma as decimal separator (3,14), so CSV files use semicolons instead of commas. Excel's default depends on system locale. Check delimiter when importing CSV from different locales.