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 Trends
Useful directional topic and query-interest research, without SEO difficulty, backlink, crawl, or SERP-depth data.
Explore and Trending Now show public search-interest patterns over time. https://trends.google.com/trends/