Regex Tester & Validator

Matches an XML declaration tag (e.g. <?xml version="1.0" encoding="UTF-8"?>) optionally preceded or followed by whitespace, as well as any leading whitespace at the very start of a string. The character class covers typical prolog attribute characters like letters, digits, quotes, equals signs, and hyphens. Typically used to strip the XML prolog and leading indentation from XML strings before merging fragments or embedding content.