Google Lighthouse is essential. It's free, it's authoritative (it's literally what Google uses), and it measures the Core Web Vitals that impact your search rankings. Every web developer should run Lighthouse. That's not the question.
The question is: what else do you need? Because Lighthouse only measures technical performance — load time, rendering, accessibility, SEO basics, and best practices. It gives you a performance score and tells you to "reduce unused JavaScript" or "serve images in next-gen formats." Important stuff, but it's only one piece of the puzzle.
Lighthouse cannot tell you whether your headline communicates value. It can't evaluate whether your CTA is compelling or buried. It doesn't know if your trust signals are credible or missing. It doesn't understand whether your page structure follows a persuasive flow. A page can score 98 on Lighthouse and still convert at 0.5% — because technical performance and conversion effectiveness are different problems.
These alternatives add the layers Lighthouse doesn't cover. Some focus on better performance monitoring. Others focus on what Lighthouse completely ignores: whether your page actually works for the humans visiting it.