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Data Format Validator

Validate data formats for free. Check JSON, XML, CSV, email addresses, URLs, UUIDs, Base64 and IP addresses, with clear error messages when something is wrong.

Validate data

Paste your data, choose the format, then validate.

Validation result

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What the validator checks

Each format has real parsing behind it, not just a pattern guess: JSON goes through the browser parser, XML through the XML parser with error reporting, and CSV is checked for consistent column counts across rows.

When validation passes you get a normalized, pretty-printed version. When it fails you get the actual error message pointing at the problem.

Formats covered

Beyond JSON, XML and CSV, the tool validates single values: email addresses, http/https URLs, UUIDs, Base64 strings and IPv4 addresses. Each check follows the practical rules those formats use in real software.

Email validation checks structure, not whether the mailbox exists. URL validation requires http or https and normalizes the address for you.

Related tools

JSON formatterFormat and validate JSON, privately. Regex testerTest regex live with highlighting. Base64 encoderBase64 encode and decode, plus URL encoder and JWT decoder.

Data Format Validator FAQs

Why does my JSON fail with a trailing comma?
Strict JSON forbids trailing commas in objects and arrays, unlike JavaScript. Remove the comma after the last item and it will validate.
My XML looks fine but fails. Why?
Common culprits are unescaped ampersands (& must be &), mismatched tags, or multiple root elements. The error message shows where the parser gave up.
Does CSV validation handle quoted commas?
The basic check counts commas per row, so quoted fields containing commas may flag as inconsistent. For complex CSV, keep quoted commas in mind when reading the result.
Is a valid email guaranteed to exist?
No. Validation only checks the format (name@domain.tld shape). It cannot confirm the mailbox is real or reachable.
Is my data uploaded anywhere?
No. All validation runs locally in your browser.
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