Verdict
Choose Nozzle when
- Research depth matters to you. Strong SERP research depth: full-result collection, snapshots, 400+ fields, historical storage and research workspaces.
- Keyword research quality for SEO content matters to you. Strong keyword/SERP insight and clustering, but not positioned as a broad keyword-volume/discovery suite.
- Context gathering matters to you. Gathers rich SERP, competitor, brand-property, local and GSC keyword context; no evidence of internal-company or arbitrary third-party app context.
Verdict
Choose WebPageTest when
- Technical SEO matters to you. Very strong Core Web Vitals and page-performance diagnostics.
- Free tools matters to you. Free tier includes substantial analysis rather than only a teaser.
- Agent readiness level matters to you. APIs, scripting, custom metrics, and CI automation make tests programmable, but no dedicated autonomous SEO agent is documented.
These tools solve different jobs. Scores are shown against each tool's own category, so the overall grades are not directly comparable. How grades work.
Read the full reviews: Nozzle and WebPageTest.