📅 May 25, 2026⏱️ 7 min read🔗 Network Tools





  Every character in a URL has a meaning. Spaces, ampersands, question marks, and non-ASCII characters must be encoded or they'll break your links. This guide explains how URL encoding works and when to use it.



  ## Why URLs Need Encoding



  URLs were designed to be read by computers, not humans. A URL like `https://example.com/search?q=hello world` contains a space — which is technically illegal in URLs. Browsers display it for convenience, but the actual encoded URL is `https://example.com/search?q=hello%20world`.



  The `%20` is URL encoding. Every character outside the "safe" set gets replaced with `%XX` where XX is its hexadecimal ASCII value.



  ## The Safe Character Set



  These characters don't need encoding in URLs:

  ```

plaintext



      Everything else — spaces, punctuation, non-ASCII characters, special symbols — must be percent-encoded.



      ## Common Encodings You Should Know







      ```

space     → %20    ! → %21    " → %22    # → %23

$ → %24    % → %25    & → %26    ' → %27    ( → %28

) → %29    * → %2A    + → %2B    , → %2C    / → %2F

: → %3A    ; → %3B    = → %3D    ? → %3F    @ → %40

[ → %5B    ] → %5D    { → %7B    } → %7C    | → %7C

  ## Query Parameters vs Path Segments



  Different parts of a URL have different encoding rules:





    - **Path segments** (e.g., `/blog/my post`) — encode everything except unreserved characters



    - **Query string keys and values** (e.g., `?q=hello`) — encode using application/x-www-form-urlencoded



    - **Query string separators** — `?`, `&`, and `=` are reserved and should not be encoded when they're serving as separators







  ## Common Mistakes to Avoid



  ### Mistake 1: Double Encoding



  If a parameter value already contains encoded data, encode it again and you'll get double-encoding:

  ```

plaintext



      Use your framework's built-in URL encoding functions rather than manual string replacement.



      ### Mistake 2: Encoding Already Encoded URLs



      Never encode a full URL — only encode the dynamic parts (query values, path segments with user content). The protocol, host, and structural characters must remain unencoded.



      ### Mistake 3: Forgetting Non-ASCII Characters



      Chinese characters, emoji, accented letters — all must be UTF-8 encoded then percent-encoded:







      ```

"你好" → UTF-8 bytes → %E4%BD%A0%E5%A5%BD

  JavaScript's `encodeURIComponent()` handles this correctly. Plain `encodeURI()` does not encode most non-ASCII characters.



  ## URL Encoding in Different Languages

  ```

plaintext



      ## Base64URL — URL-Safe Base64



      Standard Base64 uses `+` and `/`, which are unsafe in URLs. Base64URL replaces these:







      ```

Base64:    + → +   / → /   = (padding)

Base64URL: + → -   / → _   = (removed)

  Used in JWT tokens and URL-safe data transmission.



  ## Try It Yourself



  Use our [URL Encoder tool](../../tools/dev/url-encoder.html) to encode or decode any URL component. The tool automatically handles special characters, query strings, and non-ASCII text.