Question 1

What is URL encoding (percent-encoding)?

Accepted Answer

URL encoding, also called percent-encoding, converts characters into a format safe for transmission in URLs. Each unsafe character is replaced with a "%" followed by two hexadecimal digits representing its byte value in UTF-8.

For example: space → %20, ampersand → %26, forward slash → %2F.

Question 2

What is the difference between encodeURI and encodeURIComponent?

Accepted Answer

encodeURI encodes a complete URL but preserves characters that have structural meaning in URLs: : / ? # [ ] @ ! $ & ' ( ) * + , ; =

encodeURIComponent encodes everything except unreserved characters (A–Z, a–z, 0–9, - _ . ~), making it ideal for encoding individual query parameter values.

Use encodeURI for full URLs. Use encodeURIComponent for parameter values.

Question 3

What characters need to be URL encoded?

Accepted Answer

Characters that must be encoded include:
• Reserved characters: : / ? # [ ] @ ! $ & ' ( ) * + , ; =
• Unsafe characters: spaces, < > { } | \ ^ ~ ` 
• Non-ASCII characters: accented letters, emoji, CJK characters

Unreserved characters that never need encoding: A–Z, a–z, 0–9, hyphen (-), underscore (_), period (.), tilde (~).

Question 4

Is URL encoding the same as percent-encoding?

Accepted Answer

Yes. "URL encoding" and "percent-encoding" refer to the same mechanism defined in RFC 3986. The term "percent-encoding" is the formal name because each encoded character begins with a percent sign (%). "URL encoding" is the more commonly used term in everyday development.

Question 5

Why does a space become %20 in URLs?

Accepted Answer

The space character (ASCII code 32, hexadecimal 20) is not allowed directly in URLs. Percent-encoding represents it as %20 — the percent sign followed by the hex value of the byte.

Note: In HTML form submissions using application/x-www-form-urlencoded, spaces become "+" instead of %20. Both are valid but used in different contexts.

Question 6

How do I encode a URL with special characters?

Accepted Answer

To encode a full URL while preserving its structure (://?#), use encodeURI(). To encode a value that goes inside a query parameter, use encodeURIComponent().

Example: if a search query is "hello world & more", encode the value:
https://example.com/search?q=hello%20world%20%26%20more

Question 7

What is RFC 3986 and how does it relate to URL encoding?

Accepted Answer

RFC 3986 is the Internet standard that defines the syntax of Uniform Resource Identifiers (URIs). It specifies which characters are "unreserved" (safe to use as-is), which are "reserved" (have special meaning), and mandates percent-encoding for all others.

Unreserved: A–Z a–z 0–9 - . _ ~
Reserved: : / ? # [ ] @ ! $ & ' ( ) * + , ; =

Question 8

Can I batch encode multiple URLs at once?

Accepted Answer

Yes! Loopy HQ's URL encoder includes a dedicated Batch Mode. Paste multiple lines of text — each line is encoded or decoded independently. This is perfect for processing lists of URLs, query parameters, or file paths in bulk.

Question 9

How do I decode a percent-encoded URL?

Accepted Answer

Paste the encoded URL into any URL decoder tool (like this one) and it will convert %XX sequences back to their original characters. For example, %2F becomes /, %3A becomes :, and %20 becomes a space.

In JavaScript, use decodeURIComponent() for query values or decodeURI() for full URLs.

Question 10

Is my data safe? Does this tool upload my URLs?

Accepted Answer

Your data never leaves your browser. All encoding and decoding is performed client-side using built-in JavaScript functions. No URLs, text, or personal data are transmitted to any server. You can verify this by using the tool while offline.

Question 11

What is double encoding and how do I avoid it?

Accepted Answer

Double encoding happens when already-encoded text is encoded again. For example, %20 becomes %2520 (the % gets encoded to %25).

To avoid it: always decode first if you're unsure whether text is already encoded, then encode once. This tool's "Auto-detect" feature can help identify already-encoded input.

Question 12

How do I URL encode Unicode or emoji characters?

Accepted Answer

Unicode characters are first converted to their UTF-8 byte representation, then each byte is percent-encoded. For example:
• é (U+00E9) → %C3%A9 (2 UTF-8 bytes)
• 😀 (U+1F600) → %F0%9F%98%80 (4 UTF-8 bytes)

JavaScript's encodeURIComponent() handles this automatically.

Function	Preserves	Use Case
encodeURIComponent()	A–Z a–z 0–9 `- _ . ~ ! ' ( ) *`	Query parameter values, form data
encodeURI()	All of the above + `: / ? # [ ] @ ! $ & ' ( ) * + , ; =`	Full URLs (preserves structure)
Full Encoding	Nothing — every byte becomes %XX	Maximum safety, obfuscation

URL Encoder & Decoder

Batch Encode / Decode

URL Parser & Breakdown

Query Parameters

Character Inspector

URL Encoding Reference

Mode Comparison

Common Character Encodings

Unreserved Characters (never encoded)

Why use an online URL encoder and decoder?

Frequently Asked Questions