URLs do not permit certain characters to be included in them. If you do include them, the URL may break and won't operate in the expected manner.

However, data you have, including answers from the form, may include those characters and you need a way to be able to use them safely in URLs (e.g. pre-filling). To achieve that, we can use something called percent-encoding, where a code represents a character, preceded by a %.

Let's look at an example of using percent-encoding.

  • Original pre-fill URL
  • Altered URL using percent-encoding


Above, we used %40 to replace the @ in the URL. This is one of many substitutes we can apply to ensure the URL is safe to use and can operate correctly.

Here are some more examples of supported codes:

Codes to use for percent-encoding

Codes to use for percent-encoding