🔀 CSV to JSON Converter: Convert CSV to JSON Online

What is the CSV to JSON?

CSV (comma-separated values) is a plain-text table: each line is a row, and each value in a row is separated by a delimiter, usually a comma. It is the lowest common denominator for tabular data, exported by spreadsheets, databases and analytics tools alike. JSON (JavaScript Object Notation) is the structured format that web APIs and JavaScript apps expect, where data is expressed as arrays and key/value objects. Converting CSV to JSON is one of the most common glue tasks in everyday programming, and doing it correctly means respecting the quoting rules that naive splitting ignores.

When the first row holds column names, the natural conversion is an array of objects: each later row becomes one object whose keys are the header names and whose values are that row cells. So a CSV of "name,age" over two data rows becomes [{"name":"Ada","age":"36"}, ...]. If there is no header row, the safe output is an array of arrays, preserving the raw cell order without inventing key names. This tool lets you toggle between the two shapes with the header checkbox, so you get the JSON structure your code actually expects.

The part that trips up naive converters is quoting. The CSV convention defined by RFC 4180 wraps a field in double quotes when it contains the delimiter, a line break, or a quote character, and a literal quote inside is written as two double quotes. That means "London, UK" is a single field even though it contains a comma, and "Said ""bug"" first" decodes to the text Said "bug" first. A correct parser reads character by character, tracking whether it is currently inside a quoted field, rather than just splitting on commas. This converter does exactly that, so embedded commas, quotes and even newlines inside a quoted field survive the round trip intact.

CSV carries no type information, which is the second thing that surprises people. Every cell is text, so the number 36 arrives as the string "36", the word true arrives as "true", and a blank cell arrives as an empty string. JSON, by contrast, distinguishes strings, numbers, booleans and null. Because guessing types is risky (think of a ZIP code like "01730" that must not lose its leading zero, or a product code that looks numeric but is not), this tool keeps every value as a string by default and leaves the casting decision to you. Convert with Number(), parseFloat(), or an explicit check against "true" in your own code where you are sure of the column meaning.

Delimiters are the third common snag. Although "comma-separated" is in the name, real files often use other separators. Spreadsheets in locales that use a comma as the decimal mark (much of Europe) export semicolons instead, tab-separated TSV files come from databases and copy-paste, and pipe-delimited exports are popular precisely because the data itself may contain commas. If your converted JSON shows one giant key holding an entire row, the delimiter is wrong: switch it in the dropdown and convert again. The right delimiter is the single most important setting for a clean result.

Finally, remember that CSV to JSON is a structural transform, not a validation step. The converter faithfully mirrors whatever is in your file, including trailing spaces, duplicate headers, ragged rows with too few or too many columns, and stray blank lines. Clean the source where you can (deduplicate headers, trim whitespace, remove empty trailing lines) so the JSON that comes out is as tidy as the data going in. Because the whole process happens locally in your browser with no upload, it is also safe to run on private, sensitive or proprietary spreadsheets.

When to use it

• Turning a spreadsheet export into a JSON array you can drop straight into a JavaScript or TypeScript file.
• Seeding a database, mock API or test fixture from a CSV a colleague or client sent you.
• Inspecting a messy CSV to confirm exactly how quoted fields and embedded commas are being parsed.
• Converting analytics or e-commerce exports (which often use semicolons or tabs) into JSON for a script.
• Feeding tabular data into a REST API, config file or front-end app that only accepts JSON.
• Prototyping quickly by pasting a few rows and getting a JSON payload without writing any parser code.

How to use the CSV to JSON

1. Paste your CSV into the input box, or press Load sample to see the expected format.
2. Pick the delimiter that separates your values: comma, semicolon, tab or pipe.
3. Leave "First row is a header" ticked to get an array of objects, or untick it for an array of arrays.
4. Press Convert to JSON to generate the pretty-printed result.
5. Use Copy to grab the JSON, then paste it into your code, API request or file.

Formula & method

Worked examples

How a CSV maps to JSON depending on the header toggle

Common delimiters and where you see them

How CSV text values map to JSON value types

Common mistakes to avoid

• Splitting on commas and breaking quoted fields. A plain text.split(",") cuts "London, UK" into two pieces and corrupts every following column. Quoted fields must be parsed by tracking quote state, which is what this tool does.
• Expecting numbers and booleans to be typed. CSV has no data types, so every value comes through as a string ("36", "true"). Cast them in your code with Number() or a check against "true" after conversion if you need real numbers or booleans.
• Using the wrong delimiter. Files from non-US locales often use a semicolon or tab. If your JSON has one giant key per row, the delimiter is wrong; switch it before converting.
• Duplicate or blank header names. If two columns share a header, the later value overwrites the earlier one because object keys must be unique. Rename duplicate headers in the source first, or convert without a header row.
• Ignoring a leading zero or long number. A ZIP code like "01730" or a 16-digit card number loses meaning if cast to a number. Keep such columns as strings so the leading zero and full precision survive.
• Leaving stray blank lines or trailing spaces. Empty trailing lines can produce an object of empty strings, and untrimmed cells carry hidden spaces into your keys and values. Clean the source so the JSON stays tidy.

Glossary

CSV

Comma-separated values: a plain-text format where each line is a row and a delimiter separates the values within a row.

JSON

JavaScript Object Notation: a structured text format of arrays and key/value objects used widely by APIs and apps.

Delimiter

The character that separates fields in a row, most often a comma but sometimes a semicolon, tab or pipe.

Header row

The first row of a CSV that names the columns; these names become the keys in the JSON objects.

Quoted field

A value wrapped in double quotes so it can safely contain the delimiter, a line break, or quote characters.

RFC 4180

The informal standard that defines common CSV rules, including how quoting and escaped double quotes work.

Array of objects

JSON shape where each row is an object keyed by the header names, the default output when a header row exists.

TSV

Tab-separated values: the same idea as CSV but using a tab character as the delimiter between fields.

Frequently asked questions

Sources

• RFC 4180: Common Format and MIME Type for CSV Files , IETF / RFC Editor (2005)
• JSON.parse() and JSON.stringify() , MDN Web Docs