What's the file size limit?

The API endpoint accepts up to 1 MB of JSON per request. For larger files, run the formatter locally: node -e "console.log(JSON.stringify(JSON.parse(require('fs').readFileSync('input.json','utf8')),null,2))"

Yes — enable the 'Sort keys' option to sort object keys alphabetically at every level of nesting. Array element order is always preserved because arrays are ordered by definition.

What is the difference between encodeURI and encodeURIComponent?

encodeURI is designed for complete URLs — it leaves the structural characters (: / ? # & = + @) untouched so the URL remains valid. encodeURIComponent is designed for individual values within a URL — it encodes those structural characters too, preventing them from being misinterpreted as URL delimiters. Use encodeURIComponent for query parameter values; use encodeURI only if you have a full URL that you want to sanitise without breaking its structure.

Why does a space sometimes appear as + instead of %20?

HTML forms using application/x-www-form-urlencoded encoding replace spaces with + rather than %20. Both are valid in query strings, but they are different encodings. Modern APIs and URLs use %20 (RFC 3986). If you are constructing a query string for a form submission, check whether the receiving server expects + or %20.

Tool comparison

JSON Formatter vs URL Encoder / Decoder

JSON Formatter (formatting) and URL Encoder / Decoder (encoding) come from different categories but appear together in developer workflows. This guide explains what each does and when to reach for one over the other.

Bottom line

URL Encoder handles percent-encoding for query-string construction; JSON Formatter parses and displays the decoded JSON payload. When a URL contains a percent-encoded JSON parameter, decode it with URL Encoder first, then inspect the result with JSON Formatter.

What each tool does

JSON Formatter

JSON (JavaScript Object Notation) is a lightweight text format for representing structured data using key-value pairs, arrays, strings, numbers, booleans, and null. It is the dominant data interchange format for REST APIs, configuration files, and data storage. A JSON formatter parses a JSON string and re-serializes it with consistent indentation and line breaks (pretty-print) to make it human-readable, or removes all whitespace (minify) to produce the smallest possible representation for transmission or storage. This tool goes further: it validates syntax and reports the exact line and column of any parse error, optionally sorts all object keys alphabetically for consistent diffs, and can repair common JSON-like inputs that are technically invalid — such as trailing commas, JavaScript-style comments, and single-quoted strings.

Open JSON Formatter →

URL Encoder / Decoder

Percent-encoding (also called URL encoding) is a mechanism defined in RFC 3986 for representing characters that are not allowed or have special meaning in a URL. Every character that needs encoding is replaced by a percent sign followed by two hex digits representing the character's UTF-8 byte value — for example, a space becomes %20 and an ampersand becomes %26. There are two encoding variants: component encoding (encodeURIComponent) converts every character except the unreserved set A–Z a–z 0–9 and - _ . ! ~ * ' ( ); full URL encoding (encodeURI) additionally preserves the structural characters : / ? # [ ] @ ! $ & ' ( ) * + , ; = so that a complete URL remains navigable. Decoding reverses the process, converting all %XX sequences back to the original characters. URL encoding is required whenever you embed user-supplied text in a query string, form a redirect URL, construct a OAuth callback, or pass data through a system that only allows safe ASCII characters.

Open URL Encoder / Decoder →

Side-by-side comparison

Feature	JSON Formatter	URL Encoder / Decoder
Category	formatting	encoding
Primary purpose	Pretty-print or minify JSON — with syntax validation.	Encode or decode URLs and query string components using percent-encoding (RFC 3986).
Inputs	json, mode, indent, sort_keys, repair	input, mode
Outputs	output, valid, error, error_line, error_column	output, mode, changed, encoding_table

When to use each

Use JSON Formatter when…

How to pretty-print a JSON API response

Convert a minified or compact JSON API response into human-readable, indented output for inspection.

How to minify JSON for production

Remove all whitespace from a JSON file to reduce its size before embedding it in code, APIs, or config files.

Use URL Encoder / Decoder when…

How to encode a URL query parameter value

Safely embed user input or special characters in a URL query string.

How to decode a percent-encoded URL

Convert %XX sequences back to human-readable text for debugging or display.

Frequently asked questions

What's the file size limit?: The API endpoint accepts up to 1 MB of JSON per request. For larger files, run the formatter locally: node -e "console.log(JSON.stringify(JSON.parse(require('fs').readFileSync('input.json','utf8')),null,2))"
Does it sort keys?: Yes — enable the 'Sort keys' option to sort object keys alphabetically at every level of nesting. Array element order is always preserved because arrays are ordered by definition.
What is the difference between encodeURI and encodeURIComponent?: encodeURI is designed for complete URLs — it leaves the structural characters (: / ? # & = + @) untouched so the URL remains valid. encodeURIComponent is designed for individual values within a URL — it encodes those structural characters too, preventing them from being misinterpreted as URL delimiters. Use encodeURIComponent for query parameter values; use encodeURI only if you have a full URL that you want to sanitise without breaking its structure.
Why does a space sometimes appear as + instead of %20?: HTML forms using application/x-www-form-urlencoded encoding replace spaces with + rather than %20. Both are valid in query strings, but they are different encodings. Modern APIs and URLs use %20 (RFC 3986). If you are constructing a query string for a form submission, check whether the receiving server expects + or %20.