Best free tool for competition analysing

Hi guys, I don't know if this is the right place for the thread so move it if it isn't.

I don't have much knowledge about SEO. I know almost everything recommended for onsite SEO, but in offsite SEO I suck. I am developer and that's my way of earning money, but some passive income always comes in great!
For now I only have two sites, earning together aroun $40 per month (enough to pay for hosting

I have a wish to create an authority website. And to start off, I would like to research some nice keywords. Now, I am wondering, is there a free tool for analysing competition. Like, how hard it is to rank, amount of backlinks etc, some basic informations to give me insight about how hard will it be.

Thank you for helping out!

I think semrush

BHW has a 30 day free trial for SEMrush but you need to submit your credit card for that.

Apart from that, Ubersuggest has some good free limits that you can use.

I suggest to stick with free seo tools for a while, which there are many and can do many of the same thing as the paid ones do.

Desktop Programs
Link-Assistant AIO PowerSuite (recommended)
SEO Quake plugin for Firefox and Chrome (recommended)
Keyword Tool Dominator (recommended)
Vovsoft SEO Checker (recommended)

Online Apps
The SEO Tools
Search Commander
Bulk SEO Tools
Keyword Eye
GEO Ranker Free Serp Checker
Serp Surf
Ahref, SEM Rush, and Moz also have some free tools to start with.

And don't forget the bastard child... Bing Ads Keyword Planner tool. Despite its critics it is still one of my go to tools. If you are just idea searching then check out the tags, hash or otherwise in your niche on the socials, then plug them in sans the # (lots of hashtag garbage if you leave it in) into either the bing tool or something like keyword sheeter to preclude that. I have found that after doing this a while that the problem isn't finding keywords but filtering them for production. Good luck.