How to Format JSON Online (Free)
JSON straight from an API or log file is often a single minified line — impossible to read and painful to debug. This guide shows you how to format it instantly in your browser, validate it at the same time, and copy it back — without sending your data anywhere.
What You'll Need
- Any modern browser (Chrome, Firefox, Safari, Edge)
- A JSON string — from an API response, a log file, or a config file
- No software to install, no account required
Step-by-Step Instructions
Open the JSON Formatter
Go to the JSON Formatter tool. It loads in seconds and requires no login.
Paste your JSON
Click the input panel and paste your JSON. It can be minified on one line, partially indented, or already formatted — the tool handles all of these.
Choose your indentation
Above the output, pick 2 spaces (common in web projects), 4 spaces (common in Python and Java), or tabs. The default is 2 spaces.
Click Format
Press Format. Your JSON immediately appears in the right panel, properly indented with nested objects and arrays each on their own lines. If the JSON is invalid, you'll see a clear error message indicating the line and character position of the problem.
Validate your JSON
The formatter validates as it formats. A green status message means your JSON is structurally valid. A red error points you to exactly where the problem is — a missing comma, an unclosed bracket, or a stray trailing comma.
Copy or download
Click Copy to put the formatted JSON on your clipboard. Click Download to save it as a .json file. You can also use the JSON Minifier to reverse the process and compact it back to a single line for production use.
Format vs. Minify — When to Use Each
- Format for readability. Use formatted JSON when debugging, writing documentation, or inspecting an API response. Whitespace is free to humans.
- Minify for production. When embedding JSON in network responses or config files that ship with software, minification removes all whitespace and reduces file size — often by 30–50%.
- Validate before shipping. Always validate JSON before using it in code. A stray trailing comma (valid in JavaScript objects, invalid in JSON) will crash JSON parsers silently in some environments.
Is My Data Private?
Yes. The JSON Formatter runs entirely in your browser using JavaScript's built-inJSON.parse() andJSON.stringify(). Nothing is transmitted to any server. Your JSON — including any API keys, tokens, or sensitive fields it may contain — stays in your browser tab and is gone when you close it.