The best free keyword research tool overall is Moz Keyword Explorer, which offers a broad set of tools designed for keyword research and provides straightforward prioritization metrics. It has a free plan with up to 10 queries per tool per month, including 1,000 keyword suggestions and 10 SERP analyses per query. The best free keyword research tool for paid keywords is Google Keyword Planner, which is completely free and offers forecasting features for budgeting when using Google Ads. For advanced SEO professionals, Semrush provides a wide range of specialized keyword research tools with generous free plans. A simple and basic keyword research tool is Ryan Robinson's Free Keyword Research Tool, which offers unique suggested content angles but has very basic data. AI chatbots like ChatGPT can be used for simplified keyword research, but may not provide the same level of utility as dedicated keyword research tools. Upgrading from a free keyword research tool should only be considered when necessary, such as when hitting search limits or missing out on features.