If you're just starting out and have a limited budget, here are some of the best cost-effective SEO tools:
Google Search Console & Google Analytics (FREE) Essential for tracking rankings, traffic, and indexing issues.
Ubersuggest (Freemium) Basic keyword research, competitor analysis, and backlink data.
SEO Minion (FREE) Chrome extension for on-page SEO analysis and SERP preview.
Screaming Frog (Free Version) Website audit tool for broken links, duplicate content, and SEO errors.
Keyword Surfer (FREE) Chrome extension for keyword volume and related terms.