JSON Formatter & Validator
Local processing · never uploadedFormat, validate & minify JSON — right in your browser.
What is JSON Formatter & Validator?
JSON Formatter & Validator is a fast, free online tool that turns messy or minified JSON into clean, readable, properly indented text — and tells you exactly where the syntax breaks when something is wrong.
JSON (JavaScript Object Notation) is the most common format for APIs, configuration files and data exchange between services. But raw JSON is often delivered on a single line or with inconsistent spacing, which makes it nearly impossible to read or debug. This tool parses your input, validates it against the JSON specification, and re-serialises it with the indentation you choose (2 spaces, 4 spaces or tabs). You can also minify JSON back down to a single line to save bytes before shipping it to production.
When your JSON is invalid, the validator pinpoints the exact line and column of the first error and explains in plain language what went wrong — a missing comma, an unclosed string, a trailing bracket — so you can fix it in seconds instead of squinting at a wall of text.
Everything runs entirely in your browser using the native JSON engine. Your data is never uploaded to a server, never logged and never stored. That makes ToolPie safe to use even with sensitive payloads like API responses, tokens or internal configuration.
FAQ
Is my JSON data uploaded to a server?
No. All formatting and validation happen locally in your browser using the native JSON engine. Your data never leaves your device, so it is safe to paste sensitive payloads.
What does "Validate" tell me?
It checks whether your text is valid JSON. If not, it shows the exact line and column of the first error with a plain-language explanation (for example, a missing comma or an unclosed string).
Can I choose the indentation?
Yes. You can format with 2 spaces, 4 spaces or tabs, and your preference is remembered for next time.
What is the difference between Format and Minify?
Format (beautify) adds indentation and line breaks to make JSON readable. Minify removes all unnecessary whitespace to produce the smallest possible single-line output.
Is there a size limit?
There is no hard limit, but very large inputs (over ~2 MB) switch to manual mode to keep the page responsive. You can still format them by clicking the button.
Does it support comments or trailing commas?
Strict JSON does not allow comments or trailing commas, so by default they are reported as errors. This keeps your output spec-compliant.