Free online URL encoding and decoding tools

In Web development, data transmission and network interaction, URL encoding (such as %20 instead of space) and decoding are essential operations. Scenarios that require encoding: passing special characters, form submission, dynamic URL generation, API requests, security protection.

1. Passing special characters or non-ASCII characters

Problem: Only specific characters (such as letters, numbers, -, _, .) can be contained in the URL, and other characters (such as space, Chinese, &, #) need to be encoded. Example:

Space → %20 (or + in the form)
Chinese "Apple" → %E8%8B%B9%E6%9E%9C (UTF-8 encoding)
Symbol & → %26,? → %3F

# Unencoded URL (will parse incorrectly):
https://example.com/search?q=apple&orange

# Encoded URL:
https://example.com/search?q=apple%26orange

2. Form submission (GET/POST request)

Problem: The input content in the form (such as search terms, user-filled data) may contain special characters. Example:

User inputs "coffee & tea" → Encoded as coffee%20%26%20tea.

3. Dynamically generate URL parameters

Scenario: When concatenating URLs through JavaScript or backend code, you need to manually encode parameters. Code example:

const keyword = "Price>=100";
const encoded = encodeURIComponent(keyword); // Encoded as "Price%3E%3D100"
const url = `https://example.com/search?q=${encoded}`;

4. API request (such as RESTful interface)

Problem: When passing JSON data or complex parameters, you need to encode to avoid conflicts. Example:

Passing JSON string: {"name":"张三","age":25} → Encoded as %7B%22name%22%3A%22%E5%BC%A0%E4%B8%89%22%2C%22age%22%3A25%7D.

5. Prevent URL injection attacks

Scenario: When the user input content is directly concatenated to the URL, it needs to be encoded to prevent malicious characters (such as <script>). Example:

Input <img src=x onerror=alert(1)> → Encode to %3Cimg%20src%3Dx%20onerror%3Dalert(1)%3E.

In Web development, data transmission and network interaction, URL encoding (such as %20 instead of space) and decoding are essential operations. Scenarios that require encoding: server processing parameters, browser display, crawler parsing, log analysis.

1. Server receives and parses parameters

Scenario: Backend programs (such as PHP, Python) need to decode URL parameters sent by the client.

Code example (Python):

from urllib.parse import unquote
encoded_str = "%E6%9D%8E%E5%9B%9B"
decoded_str = unquote(encoded_str) # Output "李四"

2. Browser automatic decoding

Scenario: When the browser displays the URL, it will automatically decode %20 as a space, %E4%B8%AD as “中”, etc.

Example:

The user sees: https://example.com/search?q=苹果
The actual requested URL is encoded: https://example.com/%E6%90%9C%E7%B4%A2?q=%E8%8B%B9%E6%9E%9C

3. Crawlers handle dynamic URLs

Scenario: When crawlers parse web pages, they need to decode the parameters in the URL to obtain the original data.

Example:

Decode from the link /product?id=123%26category=books to get id=123&category=books.

4. Debugging and log analysis

Scenario: When viewing server logs or debugging, you need to decode the URL to understand the actual content.

Example:

Request in the log: GET /search?q=%E7%83%AD%E9%97%A8 HTTP/1.1

Decoded: q=popular