The default is caffeine-free
Chamomile, peppermint, rooibos, hibiscus, lemongrass, ginger, barley, buckwheat, corn silk and the large majority of botanicals contain no caffeine at all. If a drink needs to be caffeine-free, the herbal category is overwhelmingly the right place to look.
The exceptions worth knowing
Yerba mate contains caffeine and is drunk daily by millions across South America. Guayusa and yaupon, both hollies like mate, contain it too. Cacao husk contains caffeine and theobromine. Guarana contains a great deal. None of these is an obscure plant, and none of them is decaffeinated by being called herbal.
Decaffeinated tea is a different thing
Decaffeinated tea is Camellia sinensis with most of its caffeine removed by a solvent or carbon dioxide process. It is not caffeine-free — a residue remains — and it is not a herbal infusion. The three categories are routinely conflated on menus.
What TeaHQ publishes and does not
This site records whether a botanical contains caffeine, because that is a compositional fact about the plant. It does not publish caffeine figures for any of them, because a figure without its basis — leaf weight, water volume, temperature, time, which infusion — is decoration. That is the same standard the tea catalogue holds, where only 11 of 261 teas carry an estimate.
What this guide will not tell you
Whether a caffeine-free drink is better for you, or what caffeine does. Those are health questions and TeaHQ does not publish health content. This is about what is in the plant, not what it does in a person.