What is the difference between CSV and JSON?

CSV is a plain-text table format: one row per line, fields separated by commas, usually with a header row. It is the most widely supported data format there is, readable by every spreadsheet, database and analytics tool. JSON is a plain-text data format that stores nested objects and arrays. It is the standard payload format for web APIs, readable in any text editor, and parsed natively by every major programming language.

Will I lose anything converting CSV to JSON?

No. Both formats represent the same data model, so the values and their structure come across intact. JSON has no comment syntax. Anything stripped from a JSONC or JSON5 source is gone.

Anything to watch out for with JSON?

JSON has no comment syntax. Anything stripped from a JSONC or JSON5 source is gone. JSON numbers are IEEE 754 doubles — integers beyond 2^53 lose precision silently.

How is nested data handled?

JSON represents nesting directly, so the structure of your CSV is preserved as-is.

What should I know about starting from CSV?

CSV has no formal specification, only a convention (RFC 4180). Delimiters, quoting and line endings vary between producers. More broadly: CSV is the lowest common denominator of tabular data: one record per line, fields separated by commas, an optional header row. Every spreadsheet application, database and analytics tool reads it.

When is JSON the right choice?

JSON suits: aPI request and response payloads; configuration files that need nesting; anything consumed directly by JavaScript. It is the wrong choice when very large tabular datasets, where the repeated keys dominate the file size.

Is there a file size limit?

No hard limit — the constraint is your browser's memory. Files under 50MB convert in a few seconds. Larger files work but take longer, and a browser tab typically has 250-500MB to play with, so very large batches are better split into smaller groups.

Does this work on mobile?

Yes. The drop zone falls back to your phone's file picker, and the conversion runs on-device exactly as it does on desktop. Large files are slower on a phone because there is less CPU and memory available, but nothing about the workflow changes.

Convert CSV to JSON

Turn a CSV table into a JSON array of objects, using the header row as keys. Free, in your browser, no upload.

Drop data files to convert

JSON, YAML, XML, CSV, Parquet

Files stay on your device. Open DevTools' Network tab to verify.

Overview

Why convert CSV to JSON

JSON is the more practical choice here. API request and response payloads

Comparison

CSV vs JSON: what actually differs

CSV compared with JSON across encoding, fidelity, file size and support.
Attribute	CSV	JSON
Full name	Comma-Separated Values	JavaScript Object Notation
Encoding	Text — editor-readable	Text — editor-readable
What it preserves	Flat only — no nesting, no types, no formatting	Preserves nesting and value types exactly
Typical size	Very compact for tabular data	Verbose — keys repeat on every record
Support	Universal. Every spreadsheet, database and BI tool imports it.	Native in every programming language and every browser.

How to

How to convert CSV to JSON

01
Drop your CSV file
Drag one or more CSV files onto the drop zone above, or click to browse. Files stay on your device — there is no upload step. data formats can't be reliably identified from their bytes alone, so the extension is used to work out the source format.
02
Convert to JSON
convert.now parses the CSV and writes it out as JSON in a Web Worker, so the page stays responsive even on large files. Nothing is sent anywhere.
03
Download the result
Download the JSON file, or a zip of all of them for a batch. Filenames are preserved, with the extension changed to .json.

Why here

Why convert.now

Private
Files stay in your browser. No upload step. Nothing for anyone to see.
Fast
No queue, no upload wait. Conversion starts the moment you drop a file.
Free
No ads. No file-count limit. No sign-up wall. Just the converter.

FAQ

CSV to JSON: common questions

No. The CSV to JSON conversion runs entirely in your browser. Files never leave your device, and there is no server involved in the conversion at all. Open DevTools' Network tab and run a conversion if you want to confirm it — you will see the page and its code load, and no request carrying your file.

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Last updated 27 August 2026

Why convert CSV to JSON

CSV vs JSON: what actually differs

How to convert CSV to JSON

Drop your CSV file

Convert to JSON

Download the result

Why convert.now

CSV to JSON: common questions

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