Research depth
Discovery
How well the tool supports keyword, competitor, SERP, backlink, or market research before execution.
Copywritely
Moderate content-oriented research depth.
The SERP checker accepts up to three keywords, supports several engines/languages, and analyzes selected competitor pages for common words, bigrams and trigrams. https://copywritely.com/serp-checker/
Google Ads Keyword Planner
Useful search-demand and idea research inside an advertising workflow, without broader SEO research coverage.
Google documents keyword ideas, search frequency, trend, and campaign-forecast data for Google Ads. https://ads.google.com/home/tools/keyword-planner/