I initially bought WriterZen from StackSocial when it wasn't available at Appsumo, and I loved the innovative interface and galaxy of options, such as keyword research topic relevancy, content brief, and AI writing. A month later I see it re-emerge at Appsumo, and I happily upgraded to 4 tier to take full advantage. I love using WriterZen because it allows me to quickly conduct keyword research, identify topic and ranking opportunities, and create a solid content strategy. I find the Golden Filter and Clustering really useful features.