JSON is easy to read when it is indented, sorted into visible structures, and small enough to scan. It becomes much harder to work with after an API response has been minified, copied from logs, escaped inside another document, or edited by hand. This JSON formatter and validator is built for that everyday developer job: paste a payload, see whether it parses, and turn it into a readable shape without sending the data to a remote formatting service.
Use the input box above for API responses, webhook bodies, configuration snippets, package metadata, browser storage values, or any other valid JSON document. When the text parses successfully, the pretty view expands the object tree so nested arrays and properties are easier to inspect. The minify tab gives you a compact version for places where whitespace matters, such as environment variables, test fixtures, command line arguments, or request bodies that need to stay on one line.
Validation happens as you type. If the JSON is invalid, the page shows the parser error directly below the editor so you can look for the usual problems: trailing commas, missing quotes around object keys, unescaped line breaks inside strings, mismatched brackets, or a copied fragment that is not a complete object or array. For large payloads, start by checking the first reported error, fix that issue, then parse again. One syntax mistake can hide several later ones, so this iterative loop is usually faster than scanning the whole document.
The tool is intentionally local-first. The formatter relies on the browser JSON parser and renders the result in the page you already have open. That makes it suitable for payloads that are inconvenient to paste into third-party tools: staging API responses, private test data, internal feature flags, or debugging output from local services. You should still avoid pasting production secrets into any browser tab, but this page does not need a server round trip to do its job.
A good JSON review workflow is simple. Paste the raw payload, confirm that it validates, inspect the fields that matter, copy the formatted or minified output, and move on. When you are comparing two responses, format both first so object shape, array ordering, missing nulls, and unexpected type changes are easier to spot. When you are preparing a reproduction case, minify the final payload only after it has already validated and you have removed fields that are not relevant.
For the best results, paste complete JSON rather than JavaScript object literals. JSON requires double-quoted keys and strings, does not allow comments, and does not accept trailing commas. Those stricter rules are useful because they match what APIs, configuration parsers, schema validators, and storage systems usually expect. If your payload contains encoded data, open theBase64 encoder and decoder. If it contains Unix timestamps, check them with the Unix timestamp converter. You can also return to the UTools home page to find the rest of the browser-based developer utilities for everyday debugging workflows.