How to URL Encode Special Characters

Problem

Your URL contains spaces, ampersands, or other special characters that break the query string structure.

Prerequisites

• Basic knowledge of URL structure
• Understanding of percent-encoding

Steps

1. 1. Identify unsafe characters

   Characters like space, &, =, ?, #, and + have special meaning in URLs. Leaving them unencoded will change how the server parses the query string. Review your input and flag every reserved or non-ASCII character.

   Input

   name=John Doe & Co.

   Output

   unsafe: space, &

2. 2. Percent-encode each character

   Replace each unsafe character with a percent sign followed by its two-digit UTF-8 hex byte. A space becomes %20, an ampersand becomes %26, and a non-ASCII character may produce multiple percent sequences.

   Input

   name=John Doe & Co.

   Output

   name=John%20Doe%20%26%20Co.

3. 3. Verify the encoded URL

   Paste the encoded URL into a browser or HTTP client. The server should receive the original string exactly. If any character is still raw, the encoding was incomplete.

   Input

   name=John%20Doe%20%26%20Co.

   Output

   server receives: name=John Doe & Co.

Expected result

A fully percent-encoded URL that any standards-compliant server can parse without ambiguity.

Common errors

Encoding the entire URL including the scheme and host

Only encode the query parameter values and path segments, not the protocol or domain.

Double-encoding an already-encoded string

Check for existing % sequences before encoding. Decode first if you need to re-encode.

Troubleshooting

• If the server receives literal %20 instead of a space, the string was double-encoded.
• Use encodeURIComponent in JavaScript for query values, not encodeURI.

Security limits

• URL encoding prevents parsing errors but does not prevent injection. Validate and sanitize all input on the server side.