When should I use encodeURIComponent versus encodeURI?

Use encodeURIComponent() for individual query parameter values and URL path segments (it encodes &, =, ?, /, +, etc.). Use encodeURI() only when encoding a complete URL that already has proper structure — it preserves :, /, ?, #, and & so they retain their URL syntax roles.

Why does a space appear as %20 in some URLs and + in others?

RFC 3986 mandates %20 for space in URIs. The + notation for space originated in HTML form encoding (application/x-www-form-urlencoded, WHATWG URL spec), where + is shorthand for a space in query strings only. Both forms are valid in query strings but %20 is preferred in modern REST APIs.

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URL Encoder & Decoder

Encode special characters into percent-encoded (%20) URI format or decode them back into human-readable URLs with parameter inspector.

encodeURIComponent (Strict)encodeURI (Keep ://)

Plain URL

Encoded Output

https%3A%2F%2Fkhmertools.com%2Fsearch%3Fq%3Donline%2Btools%26lang%3Den

Detected Query Parameters

qonline tools

langen

About & How It Works

Technical calculation logic, standards, and operational details

The URL Encoder & Decoder converts special characters in URLs and query string parameters into their percent-encoded equivalents (e.g., space → %20, & → %26, = → %3D) and reverses the process for decoding. Percent-encoding, defined in RFC 3986, is mandatory for URIs because only a limited subset of ASCII characters (the "unreserved" characters: A–Z, a–z, 0–9, -, _, ., ~) are safe to use in URLs without transformation. All other characters — including Khmer Unicode, spaces, punctuation, and special symbols — must be encoded to ensure correct parsing by web servers, browsers, and HTTP intermediaries. The tool additionally offers a query string parameter inspector that parses and displays individual key-value pairs from a complete URL.

Algorithmic Logic & Calculation

The tool exposes two JavaScript encoding functions with distinct scopes. encodeURIComponent() encodes everything except unreserved characters (RFC 3986 §2.3), making it ideal for encoding query parameter values and path segments. encodeURI() preserves characters that have structural meaning in a full URI (: / ? # [ ] @ ! $ & ' ( ) * + , ; =), making it suitable for encoding a complete URL while preserving its structure. decodeURIComponent() and decodeURI() perform the respective reversals. The parameter inspector splits the query string on & delimiters and decodes each key=value pair independently.

Technical Standards & Compliance

Implements RFC 3986 (Uniform Resource Identifier: Generic Syntax) percent-encoding rules. UTF-8 encoding of non-ASCII characters follows RFC 3987 (Internationalized Resource Identifiers).

Key Features & Capabilities

Full & Component Encoding Modes

Choose between full URL encoding (encodeURI) and component encoding (encodeURIComponent) for different use cases.

Query Parameter Inspector

Parses any URL and displays decoded key-value query parameters in a clean table.

Khmer & Unicode Character Support

Properly percent-encodes Khmer Unicode characters (U+1780–U+17FF) into their UTF-8 byte-sequence percent form.

Bidirectional One-Click Conversion

Toggle instantly between encoded and decoded output without re-entering input.

Practical Real-World Use Cases

API Query String Construction

Backend developers encode search terms, filter values, and Khmer text before appending them as query parameters to REST API request URLs.

Web Scraping & URL Debugging

Developers decode encoded URLs from browser address bars or server logs to inspect raw parameter values.

Email & SMS Deep Link Generation

Marketers encode promotional content into safe mailto: or SMS deep links with pre-filled subject and body text.

How to Use

Paste the URL or text.
Choose Encode or Decode.
Copy the processed URL or inspect its query parameters.

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