CSV to JSON Free — Convert CSV to JSON Privately
Paste CSV or upload a file and get JSON in your browser. Free CSV to JSON converter — your data never uploaded anywhere. Pretty-printed output, copy or download.
CSV to JSON
All processing happens in your browser. No files are uploaded to any server. How to verify
Most online CSV-to-JSON converters work by uploading your file to a server. That's fine for sample data — but if your CSV has customer emails, transaction records, salaries, or any other private data, you've handed it to a third party for the sake of a one-line transform.
Pyrelo's CSV-to-JSON converter parses your CSV and builds the JSON entirely in your browser. Paste a snippet or upload a file — either way, the data stays on your device. The output is pretty-printed, ready to copy or download.
Why this is actually private
- ✓Both CSV parsing and JSON generation happen in JavaScript on your device.
- ✓Your data never leaves your browser — no upload, no server roundtrip.
- ✓Works offline once the page has loaded.
- ✓No analytics, no tracking, no third-party scripts on the converter.
Cmd+Option+I on Mac, F12 on Windows), go to the Network tab, then use the tool above. You'll see zero network requests during the conversion. Most online tools can't make this claim because they upload your file to do the work.How to use
- 1Paste your CSV into the textarea, or switch to 'Upload file' and drop a .csv.
- 2Pick the output shape: array of objects (header row → keys) or array of arrays (raw rows).
- 3Click Convert. Copy the JSON or download it as a .json file.
Who this is for
Seed test data
Convert a CSV export to JSON to seed a local database, mock API, or unit test fixture.
Frontend prototypes
Drop a CSV from your analytics tool into a JSON file your React or Vue prototype can import directly.
Configuration files
Translate a tabular config (feature flags, pricing tiers, role mappings) into JSON for an app to consume.
Spreadsheet → API payload
Turn a sheet of records into a JSON body you can POST to an internal API without leaking the data first.
Frequently asked questions
Is my CSV uploaded anywhere?▼
No. The CSV is parsed in your browser and the JSON is generated locally. Nothing is sent to a server. You can verify by checking your browser's network tab while you convert.
What CSV formats does it accept?▼
Standard comma-separated values with optional headers. Quoted fields with embedded commas, escaped double-quotes (""), CRLF line endings, and a UTF-8 BOM are all handled correctly. Tab-separated and semicolon-separated files aren't auto-detected — convert those to commas first.
What's the difference between 'array of objects' and 'array of arrays'?▼
Array of objects uses the first row as keys: [{"name":"Alice","age":30}, ...]. Array of arrays keeps the raw row shape: [["name","age"],["Alice",30], ...]. Most apps want array of objects; pick array of arrays if you want to preserve column order or your CSV doesn't have a header row.
What if the same header appears twice?▼
In array-of-objects mode, later columns overwrite earlier ones with the same key — that's how plain JS objects behave. If your CSV has duplicate headers, switch to array-of-arrays mode to keep every column.
How big a CSV can I convert?▼
There's no hard limit, but very large files (tens of millions of rows) may be slow because the work runs in your browser. Most business CSVs convert in well under a second.
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