JSON Formatter & Validator — free online tool

API responses and config files become readable with indentation; invalid JSON shows line-aware errors instead of silent failure.

Useful when you want a quick answer without pasting sensitive data into random chat bots.

How to use JSON Formatter & Validator

Paste raw JSON into the JSON Formatter editor—single-line API responses are fine.
Click format to indent with readable spacing, or minify to remove whitespace.
Read error messages with line hints if JSON is invalid.
Copy fixed JSON into your app config, Postman, or documentation.

Practical tips

Format to spot structure bugs; minify to ship the smallest payload in production.
Parse errors point to a line—trailing commas and unquoted keys are the usual culprits.
Treat very long integers as strings; JavaScript may round them past 15–16 digits.

Example

Paste a single-line API response, click format, then copy indented JSON into documentation.

Limitations

JSON Formatter & Validator runs on text in your tab only—there is no cloud save, version history, or collaboration. Copy results before closing the page.

Privacy & data

We do not run a database on this static site. Text and generated output exist only in your tab until you close or refresh the page.

Frequently asked questions about JSON Formatter & Validator

Why does the JSON Formatter show a line number on errors?

Invalid JSON includes a parse message from the browser engine. Fix the reported line, then format again—trailing commas and unquoted keys are common causes.

Will the JSON Formatter change number precision?

Formatting re-parses JSON in JavaScript, which uses IEEE doubles. Extremely long integers may lose precision—treat those values as strings in source data.

Does Webtoolshop store text I paste into the JSON Formatter & Validator?

We do not run a database on this static site. Text and generated output exist only in your tab until you close or refresh the page.