Characters allowed as start of HTML tag name
53
53
53Characters that are possible starts of HTML tag names, for use in "custom tags" on https://portswigger.net/web-security/cross-site-scripting/cheat-sheet
Created by: JorianWoltjer
Created on: Friday, January 30, 2026 at 12:48:10 PM
Updated on: Friday, January 30, 2026 at 12:49:03 PM
Category: HTML Parsing
Vector visibility: Public
Vector type: XSS
Vector charset: UTF-8
Template used:
<$[chr]a id="test">Code used after fuzz:
document.getElementById('test') && log(i)Your browser was detected as:
Detecting... Detecting... Detecting... Detecting...
Sample payloads
<<a id="test"><Aa id="test"><Ba id="test"><Ca id="test"><Da id="test"><Ea id="test"><Fa id="test"><Ga id="test"><Ha id="test"><Ia id="test"><Ja id="test"><Ka id="test"><La id="test"><Ma id="test"><Na id="test"><Oa id="test"><Pa id="test"><Qa id="test"><Ra id="test"><Sa id="test">Fuzz results
Chrome 144.0.0.0 desktop Windows NT 10.0
Updated
Fri Jan 30 2026
Found 53 results
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Firefox 147.0 desktop Windows NT 10.0
Updated
Fri Jan 30 2026
Found 53 results
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Microsoft Edge 144.0.0.0 desktop Windows NT 10.0
Updated
Fri Jan 30 2026
Found 53 results
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