Convert CSV to JSON, Free
Upload your CSV file and get a JSON in seconds. No account, no watermark.
How to convert CSV to JSON
CSV files store tabular data as plain text with comma-separated values, which is efficient for spreadsheets but awkward for APIs and JavaScript applications that expect JSON. Converting a CSV file to JSON turns each row into an object, using the header row as property names, so the data can be consumed directly by web apps, REST APIs, or Node.js scripts.
BoltConverter processes the conversion on our servers and produces a JSON array of objects, one per data row. The first row of your CSV is treated as the header and becomes the object keys. After conversion, both files are deleted immediately from our servers, so your data is never retained.
Upload your CSV file
Click the upload area or drag your CSV file onto the page. Make sure the first row contains column headers.
Conversion happens automatically
BoltConverter reads your CSV header row, then maps every subsequent row into a JSON object with those header names as keys.
Download the JSON file
Click Download to save the resulting JSON array to your device.
Use the JSON in your project
The output is a standard JSON array you can import into any JavaScript project, API, or database tool.
Frequently asked questions
What does the output JSON look like?
The output is a JSON array where each element is an object. The CSV header row becomes the object keys, and each data row becomes one object. For example, a CSV row 'Alice,30' with headers 'name,age' produces {"name":"Alice","age":"30"}.
Are numeric values preserved as numbers in the JSON?
All CSV values are output as strings by default, because CSV itself has no type information. If you need numeric fields as JSON numbers, you will need to post-process the output in your application.
What if my CSV uses semicolons instead of commas?
Standard CSV uses commas. If your file uses semicolons or tabs as delimiters, open it in a spreadsheet app first and save it as a proper comma-separated CSV before uploading.
Is there a row limit?
There is no row limit, but files larger than 100 MB may time out. For very large datasets, consider splitting the CSV into smaller chunks.
Are my files stored on the server?
No. Both the uploaded CSV and the resulting JSON are deleted from our servers immediately after you download the result.