About the JSON Validator

The JSON Validator checks whether a block of text is well-formed JSON and, if it is, reformats it with consistent indentation so it is easy to read. It runs entirely in your browser using the built-in JSON parser, so your data never leaves your device.

If the input contains a syntax error — a trailing comma, an unquoted key, a missing bracket — the validator reports the error message from the parser instead of producing output, which helps you pinpoint exactly what to fix before the JSON reaches your application or API.

How to use the JSON Validator

1. 1Open the JSON Validator tab.
2. 2Paste your raw JSON into the Input panel.
3. 3Click Validate & Format. Valid JSON is pretty-printed in the Output panel; invalid JSON shows an error message describing the problem.
4. 4Use Copy or Print to take the formatted result away.

How the JSON Validator works

For the JSON Validator specifically, it checks whether a block of text is well-formed JSON and, if it is, reformats it with consistent indentation so it is easy to read. Code tools use the browser’s built-in parsing engines, and nothing is uploaded — your code or text is parsed and transformed locally, which makes these tools suitable for inspecting configuration files, tokens, and payloads you would rather not send to a third party. The JSON Validator calls the native JSON.parse, which either returns a parsed object (then re-serialized with consistent indentation) or throws a syntax error pinpointing the problem — a trailing comma, an unquoted key, or a missing bracket. The XML Validator uses DOMParser, which builds a DOM tree or reports a parser error; it checks well-formedness only, not conformance to a schema or DTD. Base64 encodes binary data into 64 printable ASCII characters (A–Z, a–z, 0–9, +, /) via TextEncoder and btoa, making it safe for text channels — but it is encoding, not encryption, and is reversible by anyone with no key, so never use it to protect sensitive data. The URL Encoder uses encodeURIComponent to percent-encode reserved characters like /, ?, and &, which is correct for individual query-parameter values. The Minifier strips comments and whitespace with regular expressions while protecting string and template literals so comment stripping cannot damage URLs or quoted text; it does not rename identifiers or restructure logic. The Regex Tester compiles your pattern with the native RegExp engine and runs matchAll, so behavior matches what your production code will do, and adds the global flag automatically for highlighting when it is missing.

How this tool handles your data. This tool runs entirely in your browser. Your code or text is parsed and transformed locally using the browser’s built-in engines, and nothing is uploaded — your data never leaves your device. This makes the tools suitable for inspecting configuration files, tokens, and payloads you would rather not send to a third party.

Supported formats & limitations. The JSON and XML validators check well-formedness, not conformance to a schema or DTD. The minifier removes comments and whitespace but does not rename identifiers or restructure logic. Base64 is an encoding, not encryption — it is reversible by anyone, so never use it to protect sensitive data.

Practical workflow. In practice, you work through a short sequence: 1. Open the JSON Validator tab 2. Paste your raw JSON into the Input panel 3. Click Validate & Format. Valid JSON is pretty-printed in the Output panel; invalid JSON shows an error message describing the problem 4. Use Copy or Print to take the formatted result away. It is well suited to checking API responses and request bodies before sending them; formatting minified JSON so it is readable during debugging; catching syntax errors in configuration files before deployment.

Best practice. Validate JSON before pasting it into a config or API call, and test regex patterns with the global and case-insensitive flags to confirm they behave as expected.

Tips & common pitfalls. With the JSON Validator in particular, checking API responses and request bodies before sending them. Validate JSON before pasting it into a config or API call, and test regex patterns with the global and case-insensitive flags to confirm they behave as expected. Base64 is encoding, not encryption — it is reversible by anyone, so never use it to protect sensitive data; use the File Tools encryption utility instead. The minifier protects string literals before stripping comments, but always test minified JavaScript, especially code that relies on automatic semicolon insertion. Nothing is uploaded, so these tools suit inspecting sensitive tokens.

Troubleshooting

The first thing to know about the JSON Validator: validation and formatting run locally in your browser using the built-in JSON parser. If JSON validation fails, look for a trailing comma, unquoted key, single quotes instead of double, or a missing bracket — the parser error names the location. If XML validation fails, check for an unclosed tag, mismatched element, or unquoted attribute. If Base64 decoding errors, the input has characters outside the alphabet or a malformed length; trim extra whitespace first. If URL decoding errors, a percent sign is not followed by two hex digits. If the minifier breaks JavaScript, test the output — it protects string literals but code relying on automatic semicolon insertion can still be affected. If the regex tester shows no matches, the pattern may be invalid or simply not match; check the error message beneath the pattern field.

Common use cases

• Checking API responses and request bodies before sending them.
• Formatting minified JSON so it is readable during debugging.
• Catching syntax errors in configuration files before deployment.

Frequently asked questions

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