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.
When to use JSON Formatter & Validator
Debug API responses, pretty-print config files, and catch trailing-comma errors before deploy.
Useful when you want a quick answer without pasting sensitive data into random chat bots.
What JSON Formatter & Validator does not do
Not a JSON Schema validator, GraphQL playground, or YAML converter. Numbers follow JavaScript IEEE doubles.
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 minified API response, format it, fix the trailing comma on the reported line.
Related tools on Webtoolshop
- Base64 Encode / Decode — Decode a Base64 blob then format the JSON inside.
- Diff Checker — Compare two API responses line by line.
Limitations
Must be valid JSON to pretty-print. Trailing commas fail. Huge payloads may freeze the tab.
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.
JSON Formatter & Validator
Parse errors shown inline.