CSV to JSON Converter — Free Online Tool
Convert CSV data to a JSON array using AI. Handles headers, quoted fields, commas in values, and mixed types. Free, no sign-up.
CSV to JSON Converter — Free Online Tool
About CSV to JSON Converter — Free Online Tool
CSV to JSON converter transforms comma-separated values into a JSON array of objects, using the first row as property keys and each subsequent row as a data record. Developers use it to prepare CSV exports from spreadsheets or databases for ingestion into REST APIs, NoSQL stores, and JavaScript applications that expect structured JSON.
CSV Data Type to JSON Type Mapping
| CSV Value Example | Detected JSON Type | JSON Output Example | Notes |
|---|---|---|---|
| 42 | number | 42 | Integers parsed without quotes |
| 3.14 | number | 3.14 | Decimals preserved as-is |
| true / false | boolean | true / false | Case-insensitive match |
| 2024-01-15 | string | "2024-01-15" | Dates stay as strings; no Date object |
| null | null | Empty field becomes null, not empty string | |
| "hello, world" | string | "hello, world" | Quoted fields with commas handled correctly |
| John | string | "John" | Unquoted text always becomes a string |
CSV vs JSON vs TSV Format Comparison
| Feature | CSV | JSON Array of Objects | TSV |
|---|---|---|---|
| Human readable | Yes | Yes | Yes |
| Nested structures | No | Yes | No |
| Native browser/JS support | Via parse | Native | Via parse |
| Spreadsheet compatible | Yes | No | Yes |
| Schema enforced | No | Optional (JSON Schema) | No |
| Delimiter | Comma | N/A | Tab |
| Quoted field support | Yes (RFC 4180) | N/A | Limited |
| Streaming parse | Yes | Partial | Yes |
| Common API format | No | Yes | No |
Frequently Asked Questions
How does CSV to JSON handle missing values or empty cells?
Empty cells in CSV are converted to null in the JSON output rather than an empty string, which makes downstream null checks in JavaScript and type validation with JSON Schema more reliable. If your CSV has a trailing comma on a row (e.g., name,age,) the final field is treated as a null entry for that property.
Does CSV to JSON preserve column order in the output objects?
Yes. Property order in each JSON object follows the left-to-right column order of the CSV header row. Modern JavaScript engines (V8, SpiderMonkey) preserve insertion order for string keys in objects, so JSON.parse on the output will maintain that order in practice, though the JSON spec itself does not guarantee it.
How are quoted fields with commas or newlines handled during conversion?
The converter follows RFC 4180: fields wrapped in double quotes can contain commas, newlines, and escaped double quotes (written as two consecutive double quotes, """). This means a CSV cell like "New York, NY" correctly maps to the string value New York, NY in the JSON object without splitting into two fields.
What happens if CSV rows have more or fewer columns than the header?
If a data row has fewer columns than the header, the missing properties are set to null in the JSON object. If a row has more columns than the header, the extra values are typically discarded since there is no key to assign them to — this is standard behavior in libraries like Papa Parse and Python's csv.DictReader.
How do I convert a large CSV file to JSON without running out of memory?
For files over ~50 MB, use a streaming approach instead of loading the whole file: in Node.js, pipe a read stream through a CSV parser like csv-parser or Papa Parse's stream mode, emitting one JSON object per row. This keeps memory usage roughly constant at O(1 row) rather than O(file size), making it practical for multi-gigabyte exports.
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