I‘ve tried CleanTalk for some weeks now and I’m really impressed how easy and effective it is. I secured all my WordPress sites with one click and it just worked! All spams just blocked and a huge amount of spam IP accesses blocked via SpamFirewall (before putting load on the web server). If you use forms in WordPress I can fully recommend this plugin. Also the pricing not expensive and absolutely worth it. I also built Contao websites and tried to make it run, but this is not as easy as WP. They offer general working plugins, but this didn’t work immediately. I contacted the support and they respond really quickly. Btw. I found an extension programmed for Contao 4 in the Contao Community. They also offer a security addon. I didn’t test this out, but if it’s like the AntiSpam plugin it will be worth it, too. Generally I can fully recommend CleanTalk.