CSV Market Data to JSON for Web Apps and Charts

Web charts and apps read JSON. A price CSV converts in seconds if the types come out right.

Open the CSV to JSON converter, drop the file and turn on type detection. Check that prices are numbers and symbols are text. Keep timestamps as ISO text or unix numbers.

JSON is a list of records, each with named fields. Numbers and true/false stay as such when type detection is on, but ids and codes with leading zeros should stay text. Choose pretty JSON to read it, or compact JSON to save space.

Large histories make very large JSON files, so filter to the symbol and range you need, or use the SQL tool to take a sample, and convert that.

Everything runs in your browser and nothing is uploaded.

Open the CSV to JSON converter

Related tool pages

JSON, CSV, Parquet and Excel Converter: Convert between JSON, CSV, Parquet and Excel online for free, one file or a whole folder. It runs in your browser, so nothing is uploaded.
JSON to CSV Converter: Convert JSON to CSV in seconds. Drop a file or paste data and download the result. Private: it runs in your browser and nothing is uploaded. Large files too.
CSV to Parquet Converter: Convert CSV to Parquet in seconds. Drop a file or paste data and download the result. Private: it runs in your browser and nothing is uploaded. Large files too.
JSON to Parquet Converter: Convert JSON to Parquet in seconds. Drop a file or paste data and download the result. Private: it runs in your browser and nothing is uploaded.
Parquet to CSV Converter: Convert Parquet to CSV in seconds. Drop a file or paste data and download the result. Private: it runs in your browser and nothing is uploaded. Large files too.
Parquet to JSON Converter: Convert Parquet to JSON in seconds. Drop a file and download the result. Private: it runs in your browser and nothing is uploaded. Large files too.

How to use the CSV to JSON converter: step by step

Open the CSV to JSON converter.
Drop the file and turn on type detection.
Check the first and last records.
Download JSON.

When to use the CSV to JSON converter

Feed a price chart
Mock a market data API
Test a front end with real prices
Share a sample as JSON

Example

Input: id,name,age 1,Ada,36 2,Alan,41

Output: [{"id":1,"name":"Ada","age":36},{"id":2,"name":"Alan","age":41}]

Frequently asked questions

How do I convert CSV to JSON?

Drop your CSV file (or paste the data), check the options, click Convert and download the JSON result.

How big can a file be?

It depends on your device. A few hundred MB usually works.

Which conversions does the Format Converter support?

Any direction between JSON, CSV, Parquet and Excel (.xlsx), for one file or a whole folder. Nested JSON is flattened into columns such as address.city. For Excel, the first sheet is read; old .xls files are not supported.

Why did my number or date change after converting?

Types are detected from the values. Turn off "Detect types" to keep everything as text, which also keeps leading zeros in IDs and phone numbers.

Tip: Filter a long history first. A multi-year minute history makes a huge JSON file.