Here are the five best keyword research tools I recommend for startups to begin a well-rounded keyword foundation for SEO.
1. Google Keyword Planner
2. KWFinder
3. Moz’s Keyword Explorer
4. Keyword Tool
5. SEMrush
Google Keyword Planner is very helpful.
I will recommend trying SERPLAB. I am using it and I will recommend it to anyone who want to monitor change of keyboard as compared to the competitor's website. SERPLAB also show keyword ranking of competitors site as well.
Google keyword planner and Google trends are best free tools to analyse keyword research. Many third party tools also available like Moz is also provide for keyword research but these tools are paid tools.