Instantly format, beautify, validate, and minify JSON. Detects errors with line numbers. Works completely offline in your browser.
The Logrith JSON Formatter beautifies, validates, minifies, and sorts JSON data instantly in your browser. Paste in compact or malformed JSON and get back properly indented, readable output — or catch a syntax error with the exact character position where parsing failed. This is one of the most frequently needed tools for anyone working with APIs, configuration files, or structured data.
JSON (JavaScript Object Notation) is the most widely used format for exchanging structured data between systems, especially in web APIs. In its raw form, especially when returned by an API without formatting, JSON often arrives as one long unbroken line of text — technically valid but nearly impossible to read or debug by eye. This tool adds proper indentation and line breaks, turning that dense block into a clearly structured, nested view that's easy to scan and understand.
JSON has a stricter syntax than JavaScript object literals, and the differences trip people up constantly. A trailing comma after the last item in an object or array — valid in some JavaScript contexts — is invalid in strict JSON and will cause a parse error. Keys must always be wrapped in double quotes, never single quotes or left unquoted, even though unquoted keys are valid in plain JavaScript objects. String values must also use double quotes, not single quotes. Special characters inside strings, like a literal quote mark or newline, need to be escaped properly or they'll break the surrounding string. This tool's validator catches all of these issues and reports the exact position where the problem occurs, saving you from manually scanning through a long JSON blob looking for a single misplaced comma.
Beyond simply looking nicer, properly formatted JSON is significantly easier to debug. When an API response or configuration file is returned as one dense line, finding a specific field, understanding the nesting structure, or spotting a missing value means scrolling through a wall of text character by character. Formatted JSON, with each key-value pair on its own indented line, lets you visually trace the structure — which object a field belongs to, how deeply nested an array is, where one object ends and another begins — at a glance.
While formatted JSON is better for human reading, minified JSON has its own purpose: reducing file size. When JSON is being sent over a network — as an API request or response, or embedded in a web page — every unnecessary whitespace character adds to the payload size and, at scale, to bandwidth and loading time. Minifying strips all of that extra whitespace while keeping the data itself completely unchanged, producing a smaller file that parses identically to the formatted version. Development and debugging typically call for formatted JSON; production and network transfer typically call for minified JSON.
All JSON processing happens locally in your browser using JavaScript's built-in JSON.parse() and JSON.stringify() functions — your data is never uploaded to a server or stored anywhere. This makes the tool safe to use with JSON containing API keys, internal configuration, or other sensitive structured data.
When two JSON objects contain the same data but their keys are in a different order, a plain text comparison will flag them as different even though they're functionally identical. Sorting keys alphabetically before comparing removes this ordering noise, making it much easier to spot genuine differences between two JSON payloads — for example, when debugging why an API response doesn't match an expected test fixture, or when comparing two versions of a configuration file that were edited independently.