The Format Behind Almost Every API
JSON (JavaScript Object Notation) is the most widely used data interchange format on the web. When your browser fetches data from an API, the response is almost certainly JSON. When you configure a modern application, the settings file is often JSON. When systems exchange data, JSON is the default language.
A simple JSON object looks like this:
{"name":"Alice","age":30,"active":true}
That is valid JSON — but it is nearly impossible to read when the object has dozens of fields or nested structures. Formatting (or "pretty-printing") adds indentation and line breaks to make the structure visible.
Why Formatting Matters
Minified JSON — compressed into a single line with no whitespace — is efficient for transmission but hostile to humans. When debugging an API response, reviewing a configuration file, or inspecting data, you need to see the structure.
Formatted JSON reveals:
- Nesting levels. You can see which objects are nested inside which. A 5-level-deep structure that is unreadable on one line becomes clear with indentation.
- Missing or extra commas. JSON syntax errors are often missing or trailing commas. Formatting makes the error location obvious.
- Data types. Strings in quotes, numbers without quotes, booleans, nulls, arrays in brackets — all visible at a glance.
- Array contents. A 50-item array on one line is a blur. Formatted with one item per line, you can scan it quickly.
JSON Syntax Rules
JSON is strict. Unlike JavaScript objects, JSON requires:
- Double quotes only. Keys and string values must use
"double quotes", never single quotes. - No trailing commas. The last item in an array or object must not have a comma after it.
- No comments. JSON has no comment syntax. This is by design — JSON is data, not code.
- No undefined. Valid values are strings, numbers, booleans (
true/false),null, objects, and arrays.
A single syntax error makes the entire JSON document invalid. Most parsing errors are missing quotes, trailing commas, or single quotes instead of double.
Common JSON Tasks
Formatting: Expand minified JSON into readable, indented structure.
Minifying: Compress formatted JSON into a single line for storage or transmission.
Validating: Check whether a JSON string is syntactically correct and identify the location of errors.
Comparing: Spot differences between two JSON documents by formatting them identically and comparing side by side.
Extracting: Pull specific values from a large JSON structure by navigating the formatted tree.
How to Use the Toobits JSON Formatter
Paste your JSON into the input field. The tool instantly formats it with proper indentation, syntax highlighting, and validation. If the JSON contains errors, you will see the error location and description. Copy the formatted output for use in documentation, code, or debugging. Everything runs in your browser — your data never leaves your device.