Convert CSV to JSON, Excel to JSON Offline
Load CSV or Excel files and convert to JSON instantly. Export JSON arrays back to CSV or XLSX. All processing happens locally on your desktop.
Get the tool mentioned in this guide in the desktop app:CSV / Excel ↔ JSON Converter
Why convert CSV to JSON?
CSV (Comma-Separated Values) is human-readable and spreadsheet-compatible but lacks structure for nested data. JSON is hierarchical, supports arrays and objects, and parses directly into JavaScript.
Converting CSV to JSON is common when importing spreadsheet data into a database, feeding data into an API, or processing user-uploaded files. Conversely, exporting JSON to CSV makes it easy to open results in Excel for further analysis.
How CSV to JSON conversion works
The first row of your CSV becomes the object keys. Each subsequent row becomes an object with those keys. The result is an array of objects, ready to parse in JavaScript or send to an API.
// CSV input (with header)
name,age,email
Alice,30,[email protected]
Bob,25,[email protected]
// JSON output
[
{ "name": "Alice", "age": 30, "email": "[email protected]" },
{ "name": "Bob", "age": 25, "email": "[email protected]" }
]Excel to JSON with date handling
When converting XLSX (Excel) files, dates are automatically converted to ISO 8601 strings. For example, an Excel date like "Jan 15, 2025" becomes "2025-01-15T00:00:00Z" in JSON, which is universally parseable.
// Excel columns: Name, Hired, Salary
Name,Hired,Salary
Alice,2025-01-15,75000
Bob,2024-06-20,65000
// Becomes
[
{ "Name": "Alice", "Hired": "2025-01-15T00:00:00Z", "Salary": 75000 },
{ "Name": "Bob", "Hired": "2024-06-20T00:00:00Z", "Salary": 65000 }
]JSON to CSV export
Export an array of JSON objects back to CSV for use in spreadsheet tools. MyDevTools extracts all unique keys from the objects and creates headers, then writes each row with values in the same column order.
Use cases
Data import — Convert user-uploaded spreadsheets into JSON for bulk inserts into a database.
Integration testing — Load test data from a CSV, convert to JSON, and feed into an API.
Reports — Export API results as JSON, convert to CSV, open in Excel for pivot tables and charts.
ETL workflows — Transform CSV data, process it, and export back to CSV or another format.
Frequently asked questions
What if my CSV has quoted fields with commas inside?
Standard CSV parsing handles quoted fields correctly. Wrap values containing commas in double quotes.
Can I convert nested JSON to CSV?
Nested objects or arrays cannot be directly represented in CSV (which is flat). Flatten the JSON first or export a simplified structure.
Is the file upload secure?
The MyDevTools CSV/Excel converter is a desktop tool that processes files entirely on your machine, offline. Nothing is uploaded to a server — your file stays on your device.