Format, validate, and inspect JSON data with syntax highlighting, detailed validation errors, and an easy-to-read structured output.
Format, minify, validate, and inspect JSON directly in your browser.
Quickly format or optimize valid JSON depending on how you need to use the result.
Validates the JSON and expands it into an easier-to-read structure.
Validates the JSON and removes unnecessary whitespace for a compact result.
Explore formatted JSON as an expandable object and array structure.
Drop a local .json file into the input editor to load its contents.
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ToolTunnel JSON Formatter is a browser-based tool for formatting, validating, minifying, and inspecting JSON data. It helps developers turn compact or difficult-to-read JSON into structured, readable output and quickly identify syntax errors such as missing commas, incorrect quotes, or malformed brackets.
JSON (JavaScript Object Notation) is a lightweight text format commonly used to exchange structured data between applications. It is widely used by REST APIs, configuration files, cloud services, command-line tools, and web applications.
A JSON document is built from objects, arrays, strings, numbers, booleans, and null values. Because JSON has strict syntax rules, even a small formatting mistake can make an otherwise useful document invalid.
The formatter parses your JSON and produces readable, consistently indented output. If the input is invalid, the tool reports the parsing error and, when available, provides the relevant line and column so you can locate the problem faster.
You can also switch between a formatted code view and a tree view to inspect the structure of objects and arrays without manually navigating through large JSON documents.
Formatting adds whitespace and indentation to make JSON easier for humans to read and edit. It does not change the underlying data structure.
Minification removes unnecessary whitespace to produce a smaller JSON representation. Minified JSON is useful when compact payloads are preferred, such as API requests, generated configuration, or data passed between applications.
JSON uses stricter syntax rules than JavaScript object literals. Property names must use double quotes, strings must use double quotes, and object properties must be separated with commas.
Common problems include missing commas, unmatched braces or brackets, single-quoted strings, unquoted property names, invalid escape sequences, and trailing commas.
The tree view provides a structured representation of parsed JSON. It can make deeply nested objects and arrays easier to understand than a plain text representation, especially when working with API responses or configuration data.
The tree view is available when the JSON has been successfully parsed. Invalid JSON cannot be represented as a structured tree until the syntax errors are corrected.
You can open a JSON file directly in the tool or drag and drop JSON content into the workspace. File processing is performed in your browser, so the tool does not need to upload your JSON to a remote processing service.
This makes the formatter useful for inspecting configuration files and other structured data where keeping the content in the current browser session is preferable.
JSON and YAML are both commonly used for structured data and configuration, but they have different syntax and design goals. JSON is particularly common for APIs and machine-to-machine data exchange, while YAML is often preferred for human-edited configuration.
If you need to convert between the two formats, ToolTunnel also provides a JSON ↔ YAML Converter.
The JSON Formatter is designed for client-side use in your browser. Your JSON is processed locally by the web application rather than being sent to a server for formatting.
Even with local processing, avoid pasting credentials, access tokens, passwords, private keys, or other highly sensitive information into any online tool unless you understand the security requirements of your environment.
A JSON formatter takes JSON data and adds readable indentation and whitespace while preserving the underlying data structure. It is useful for making compact or difficult-to-read JSON easier to inspect.
Yes. The formatter parses the input before producing formatted or minified output. Invalid JSON produces an error instead of formatted output.
Common causes include missing commas, unmatched brackets or braces, single quotes, unquoted property names, trailing commas, invalid escape sequences, and other characters that are not valid JSON syntax.
No. Standard JSON does not support comments. Some applications implement JSON-like formats that allow comments, but those documents are not valid standard JSON.
No. Standard JSON does not allow a comma after the final property in an object or the final element in an array.
Formatting adds indentation and whitespace to improve readability. Minifying removes unnecessary whitespace to create a more compact JSON document. Neither operation is intended to change the actual data.
Yes. You can open a JSON file from your device and format its contents in the browser.
Yes. After valid JSON is parsed, the tool provides a tree view that represents nested objects and arrays hierarchically.
The formatter processes JSON locally in your browser. However, you should still avoid entering credentials, private keys, access tokens, or other sensitive secrets into web-based tools.
The formatter can handle many normal development and configuration files directly in the browser. Very large documents may consume significant browser memory and processing resources.