Online JSON Validator

A JSON validator checks whether a payload conforms to the JSON specification — every bracket balanced, every key quoted, every separator in place. JSON Pretty validates as it parses, so the moment you paste, you know if the input is structurally sound.

Trailing commas, single quotes instead of double, unquoted property keys, missing commas between items, unescaped characters inside strings, hidden byte-order marks — anything that breaks strict JSON. Each error comes with a line number and a snippet of the surrounding text.

No. The validator follows strict JSON (RFC 8259). Inputs with comments, trailing commas, or unquoted keys are flagged so you can clean them before sending the document to an API or saving it as a .json file.

Yes. The parser runs off the main thread, so even multi-megabyte JSON files validate without freezing the page. You can paste raw text or upload a .json file directly.

Yes — and entirely client-side. Every check runs in your browser. JSON Pretty does not send your input to any server, log it, or store it after you close the tab.

A typical online JSON validator gives you a yes/no answer. JSON Pretty pinpoints the broken line, shows a snippet around the error, and hands the payload to the full editor so you can fix it in place — without bouncing between tabs.