This is a classic question, Wasim. A few free tools actually offer you a good start in SEO, but it might feel like a jungle of expensive tools and glitzy dashboards when you first start.
You should definitely set up Google Analytics and Google Search Console. They provide you with actual data directly from the source and are free, which is more beneficial than it first appears.
The free version of Screaming Frog allows you to crawl up to 500 pages. It's ideal for identifying strange redirect chains, missing tags, and broken links.
For rapid audits, SERP previews, and on-page checks, SEO Minion is an excellent Chrome addon.
For technical fixes, Google's own tools, such as PageSpeed Insights and Mobile-Friendly Test, are extremely useful but underappreciated.
Additionally, a limited amount of free keyword data without credits is now provided by Keywords Everywhere. Although it's not as comprehensive as commercial tools, it's still helpful for beginners.
Although they might not be able to completely replace expensive instruments, if you use them consistently, they can help you get far.