Semrush

Semrush is a comprehensive online platform for SEO and digital marketing, built by the company of the same name, one of the best-known players in the field. It bundles dozens of tools into a single interface, so instead of stitching together five separate apps you get keyword research, backlink analysis, technical audits and competitor tracking under one roof. It suits content creators, bloggers, online stores and marketing agencies that care about their visibility in search engines.

It works like this: you enter a domain or a keyword and Semrush returns an overview from its own huge database — how many people search for the term each month, how hard it is to rank for, which pages already rank for it and where they get their links. For your own site you run an audit that crawls the pages and lists technical errors, and position tracking shows you day by day how you move in Google's results. So it measures traffic, keywords, the backlink profile and the technical health of a site.