validate (check vars) (tag)

is_email()

Verifies that an email is valid.

rest_is_boolean()

Determines if a given value is a boolean or boolean-like. Doesn't look at the type of a given value, and like in PHP, 1 = true and 0 = false.

validate_file()

Validates a file name and path against an allowed set of rules.

wp_http_validate_url()

Validate a URL for safe use in the HTTP API.

wp_validate_redirect()

Validates a URL for use in a redirect.