What is URL encoding?

URL encoding, also called percent-encoding, replaces characters that aren't safe in a URL — like spaces, &, and non-ASCII letters — with a % followed by two hexadecimal digits representing the character's byte value.

What's the difference between encodeURIComponent and encodeURI?

encodeURIComponent (Component mode) escapes nearly every special character, including / , : and &, so it's safe for a single query value or path segment. encodeURI (Full URL mode) leaves those structural characters untouched because it expects a complete, valid URL.

Why do I get an error when decoding?

Decoding fails when the input contains a % that isn't followed by two valid hexadecimal digits, or a broken multi-byte UTF-8 sequence. Double-check the encoded string was copied in full and hasn't been altered.

Why does my URL contain %2520 or other double-encoded characters?

%25 is the encoded form of the % sign, so %2520 means text that was already encoded (%20) got encoded a second time. Decode it once to get back the correct value, and only encode raw text, never a string that is already percent-encoded.

Does this work with non-English characters?

Yes. Any Unicode character, including accented letters, Chinese, Japanese, or emoji, is converted to its UTF-8 byte sequence and then percent-encoded, so the result is always plain ASCII-safe text.

Why do spaces become %20 or +?

In a URL path or query value, encodeURIComponent turns a space into %20, its correct percent-encoded form. Some older systems and HTML form submissions instead use + for spaces in the query string — a separate, form-specific convention this tool does not apply, since %20 is the universally correct encoding.