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/
Wincher
Strong keyword and SERP research coverage.
Keyword Explorer provides search volume trends, difficulty/context, daily SERP preview, top-10 averages, and top-page word count, backlinks, and domain strength: https://www.wincher.com/keyword-explorer