Free URL Encoder and Decoder – Safe Data Transmission

Safely encode or decode URLs and text containing special characters or non-ASCII letters for secure web transmission.
We fully support various global charsets including UTF-8, ASCII, and the ISO-8859 series.

Eliminate data errors with our prevent double-encoding feature, ensuring your strings are converted perfectly every time.
All conversions are processed locally in your browser, keeping your sensitive data 100% secure.

Seamlessly integrate this tool with Vivoldi’s Base64 Encoder or JSON Formatter to boost your daily development workflow.

3D illustration of Vivoldi’s URL Encoder and Decoder tool, showing raw text transforming into secure percent-encoded URL strings | URL encode, URL decode, percent encoding

Encoding results:

Decoding results:

Why is ‘URL Encoding’ essential for a secure web environment?

Web addresses (URLs) are designed to communicate strictly using safe ASCII characters.
Therefore, transmitting parameters or query strings containing international characters, special symbols, or spaces as-is can lead to severe data loss or connection errors (400 Bad Request).
The ‘Vivoldi’ converter is the smartest web development utility that blocks these errors at the source.

  • Prevent Fatal Double Encoding: We guarantee safe substitution through the ‘Double-encoding prevention’ option, which stops you from accidentally re-converting an already encoded string and corrupting your data.
  • Support for Diverse Global Charsets: We fully support most existing text standards, from basic UTF-8 to EUC-KR, ISO-8859, and UTF-16, ensuring compatibility even with legacy systems.
  • Perfect Security & Privacy: Input API keys and sensitive parameter values are never sent to a server. Everything is processed instantly within your browser, ensuring it is 100% secure.

Have questions?
Check the FAQ.

URL encoding (percent-encoding) is the standard method of converting Unicode, spaces, and special characters in a web address (URL) into % symbols with numeric codes.
For example, a space becomes %20, and symbols like “?” or “&” are replaced with their unique codes.

This ensures that browsers and servers interpret characters consistently, making it essential to prevent broken links or data loss.

URL encoding is most commonly used in the following cases:

  • When generating URLs with query string parameters
  • When sending HTML form data using application/x-www-form-urlencoded
  • When sharing external links with international characters or emojis

Therefore, URL encoding is not just character conversion—it is a core technology for web development, SEO, and security.

If a URL-encoded string is encoded again, the % symbol becomes %25, resulting in a double-encoded state.
For example, the Korean character 가 → %EA%B0%80 → encoded again becomes %25EA%25B0%2580.

When double encoding occurs, browsers or servers may misinterpret the data, leading to broken links, corrupted parameters, or failed API calls.
Therefore, URL encoding should be applied only once when needed, and strings already encoded multiple times must be decoded repeatedly to restore the original.

In particular, API integrations, query string transfers, and external service calls are prone to such issues, so always check the encoding status to avoid errors.

Yes. Vivoldi’s URL encoding/decoding tool automatically and accurately converts not only Korean, Japanese, Chinese, and other multilingual characters, but also special symbols like spaces ( ), %, &, #, and =.

Complex website addresses, query parameters, and external links can be handled easily with copy → paste → instant conversion, and results are displayed in real time.

This feature is especially useful for web development, data transmission, email link creation, and global service operations, helping prevent encoding errors and ensuring efficient workflows.