SmartQueryTools

Convert Case in JSON Files Online

Convert text columns to UPPERCASE, lowercase, or Title Case in JSON files directly in your browser. Apply case conversion to any or all text columns at once — no upload required.

How to convert Case in JSON files

  1. Drop your file onto the upload area. Every text column is ticked by default and the first 200 rows are shown.
  2. Choose the case type: UPPERCASE, lowercase or Title Case. One case type applies to every ticked column in a run.
  3. Adjust the columns under Apply to columns. Only text columns are listed. The All and None links tick or clear them all.
  4. Click Convert Case, check the preview, and download the file in the same format.

Your file is processed locally in your browser and is never uploaded. The free limit is 50 MB per file; larger files work if your device has the memory for them.

Worked example

Newsletter sign-ups were merged from two web forms, and email addresses arrive in mixed case. The mailing tool treats Jo.Bloggs@Example.COM and jo.bloggs@example.com as different contacts.

Input (JSON)

[
  {
    "email": "Jo.Bloggs@Example.COM",
    "country": "NZ",
    "visits": 3
  },
  {
    "email": "mika.k@example.fi",
    "country": "fi",
    "visits": 1
  },
  {
    "email": "ANNA.W@EXAMPLE.DE",
    "country": "DE",
    "visits": 7
  },
  {
    "email": "r.osei@example.gh",
    "country": "GH",
    "visits": 2
  }
]

Settings

  • Case type: lowercase
  • Apply to columns: email only (country unticked; visits is a number and is not listed)

Result

emailcountryvisits
jo.bloggs@example.comNZ3
mika.k@example.fifi1
anna.w@example.deDE7
r.osei@example.ghGH2

Only the email column changes. Addresses that were already lowercase are left as they were. The country column was unticked, so "fi" is still lowercase. A second run with UPPERCASE and only country ticked would fix it. The visits column is a number and passes through unchanged.

Working with JSON files

Top-level string keys are ticked by default, and their values are converted in every object. The key names themselves are not changed, so {"Status": "OPEN"} lowercased becomes {"Status": "open"}. Numbers, booleans and null values are left as they are. A key that holds numbers in some objects and text in others is loaded with a JSON type and is not listed. Lowercase also turns placeholders such as "N/A" into "n/a", so downstream checks for those values may need updating.

Nested objects and arrays cannot be converted, so they are not listed. If the field you need is inside an object, such as customer.email, flatten the file first so it becomes a top-level key. Converting enum-style fields like "status" or "type" to one case is a common step before loading JSON into a system that validates values against a fixed list. The output is a JSON array with the same keys in the same order.

Frequently Asked Questions

Does Convert Case change JSON key names?

No. Only string values in the ticked keys change. Key names stay exactly as they were.

Can I lowercase an email field inside a nested JSON object?

Not directly. Flatten the JSON first so the nested field becomes a top-level key, then tick it here.

Can I apply different cases to different columns?

Not in one run. Each run applies one case type to all ticked columns. Run the tool again on the downloaded file with the other columns ticked.

Which columns can I convert?

Text columns only, and those are the only ones listed. Number, date and boolean columns have no letters to convert, so they are left unchanged.

Does it trim spaces or fix accents?

No. It only changes letter case. Accented letters are converted correctly, for example é to É, but spaces and punctuation are left alone. Use Trim Whitespace for spaces.

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