URL Encoder / Decoder - Free Online Percent-Encoding Tool
Uniform Resource Identifiers (URIs) only support a restricted set of ASCII characters. Any non-ASCII text (such as Korean or Japanese characters) or reserved symbols (&, ?, =, #) inside query parameters must be percent-encoded (e.g., %20, %EA%B0%80) to prevent broken links and server-side parsing failures.
When to Use This Tool
- OAuth Redirect URI Setup: Safely encode callback URLs containing multiple query parameters for OAuth2 authorization flows.
- Non-ASCII Search Queries: Convert multi-byte strings (Korean, Japanese, emojis) into valid HTTP request query strings.
- Query Parameter Debugging: Paste unreadable URLs like "%EC%95%88%EB%85%95" to inspect the human-readable parameter names and values.
- Preventing Reserved Character Collisions: Ensure that ampersands (&) and equals signs (=) inside parameter values are not misinterpreted as delimiters.
How to Use
- Select Action: Choose "Encode" to convert special characters to %XX, or "Decode" to restore original text.
- Input Text or URL: Paste the target URL or query parameter text into the input field.
- Choose Mode: Select encodeURIComponent (for query values) or encodeURI (for full URL addresses).
- Copy Result: Copy the transformed, clean URL string directly to your clipboard.
Input & Output Example
Input:
https://example.com/search?keyword=개발자 도구&category=API+디버깅
Output:
https%3A%2F%2Fexample.com%2Fsearch%3Fkeyword%3D%EA%B0%9C%EB%B0%9C%EC%9E%90%20%EB%8F%84%EA%B5%AC%26category%3DAPI%2B%EB%94%94%EB%B2%84%EA%B9%85
Frequently Asked Questions (FAQ)
Q. What is the difference between encodeURI and encodeURIComponent?
A. encodeURI preserves valid URL structure characters like : / ? # & =. In contrast, encodeURIComponent encodes almost all special characters including /, ?, and &, making it strictly necessary for parameter values.
Q. Why is space sometimes encoded as "+" and sometimes as "%20"?
A. In standard URI percent-encoding (RFC 3986), a space is always %20. However, in HTML form submissions (application/x-www-form-urlencoded), historical conventions allowed spaces to be replaced by a plus sign (+).
Q. Can URL encoding prevent SQL injection or XSS?
A. URL encoding ensures parameters are delivered without protocol corruption, but it is NOT an application-level security defense against SQL injection or XSS. Always sanitize and use parameterized queries on your backend.
Engineering & Privacy Notes
- Processes strings locally in your browser with zero network latency and complete privacy.
- Supports standard RFC 3986 percent-encoding rules for modern REST APIs and web platforms.
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