CSV to JSON Converter — With Type Detection and Nesting

Convert CSV or TSV into a JSON array, with header detection, type inference and nested keys from dot paths.

Free, with no sign-up and no watermark. The file is processed in your browser and never uploaded.

Turn CSV or TSV into a JSON array. The delimiter is detected automatically, numbers and true/false become real JSON types if you want, and headers like address.city can be rebuilt into nested objects. Quoted fields with commas and line breaks are handled correctly.

Step by step

  1. Add CSV: Paste it, use Open file (.csv, .tsv, .txt) or Load sample.
  2. Check the delimiter: Leave Auto-detect on, or force comma, semicolon, tab or pipe.
  3. Choose options: First row is a header makes objects; untick it to get arrays of values. Detect numbers & booleans converts 42 and true.
  4. Nest keys: With Nest "a.b" headers, a column named address.city becomes { "address": { "city": … } }.
  5. Download: Save the result as data.json.

Handy for

Seeding apps

Turn a spreadsheet into fixture data for an app or test.

Config from sheets

Let non-developers maintain lists in a sheet and convert them to JSON.

APIs

Prepare a JSON body from tabular data.

Data cleaning

Spot rows with too many or too few fields — they are reported as errors.

Good to know

  • Turn off number detection if you have IDs with leading zeros (like PIN codes or phone numbers) — otherwise 0123 becomes 123.

  • Blank lines are skipped automatically.

  • Exported from Excel with semicolons? Auto-detect handles that.

Questions

Does it handle commas inside values?

Yes, as long as the value is wrapped in double quotes, which is what spreadsheets do when exporting.

How big a file can I convert?

Tens of thousands of rows work comfortably; the limit is your device's memory.

Is my data sent anywhere?

No. Everything is processed by JavaScript in your browser tab — nothing you paste or open is uploaded, logged or stored on a server. You can even use the tool offline once the page has loaded.

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