Hlo Friends,
What are the free and popular keyword research tools?

Google keyword planner is the best free tool for high quality keyword research. They help to provide various keyword suggestions for your domain, and selecting the right keywords will help to rank your website higher in search results.

Google Keyword Planner
KWFinder

- Google Keyword Planner
- Keywordtool.io

According to my personal experience, Google keyword planner is the best keyword research tool.

I think Google AdWords is the best, and popular keyword research tool. The most obvious choice for the top spot, this free keyword tool has been a favourite for many years.

There are some free keyword research tool that can be useful for SEO,

Google Trends;
Keyword Sheeter;
Answer the Public;
Keyword Surfer;
Keyworddit;
Keywordtool.io;
Google Search Console;
Questiondb;
Bulk Keyword Generator;