Semrush - This is one of only two tools that I log into every single day. I use this for assisting with site audits, competitor organic and paid research, keyword research, and content generation/marketing.
Then there are the Google Tools:
Google Search Console
Google Tag Manager
Google Optimize - If you are not familiar with this one, I use it primarily for A/B conversion testing.
Google Data Studio - I just want to mention that this is one I think is underutilized and under appreciated. With Data Studio you can pull data from Analytics, Search Console, and Google Ads and combine and present it how you want. You can also much more easily segment the data. If you are working with clients, you can make all that data more appealing to the eye and emphasize what you want them to focus on as well (like leads, sales, etc.).
Google Chrome Developer Tools
Auditing / Monitoring Tools:
Screaming Frog - I know a lot of people like SiteBulb instead. They do pretty much the same thing, but Screaming Frog does it faster and is less resource intensive.
ContentKing App - It has great monitoring features, but also lets me easily dig through and segment pages. Too much to cover here, but a great tool.
Perrfy - This has potential to replace ContentKing App at a much lower price. It's not officially launched yet. I was invited to test it the past few months and it is a great tool.
Jasper.AI - There are plenty of AI writing tools out there and it seems like new ones popping up each day now. I prefer this one. I use it to boost our content generation. I do not create content in Jarvis and post it straight to websites. Everything gets edited first, but it really speeds things up versus writing from scratch.
I do not use it just for writing articles. I use it for helping to generate ad copy and headlines. I use it to help generate title tags and H tags in articles. I don’t often use something it generates for these, but I will have it write 20-25 variations of a title tag, and use those to create something myself. I’m constantly finding new ways to use this.
Frase - Love this for generating content briefs for writers and picking apart data, headings, questions, etc. used in top ranking sites for queries. Great tool for writing content. Very similar to Surfer SEO, but I like it better.
Answer the Public - Great tool for generating additional ideas for content and keyword research.
SEOPress - I’m not a fan of Yoast and anyone using it is doing so at their own peril, or the peril of their clients. Yoast has a long history of releasing updates with bugs in it, sometimes site and SEO crippling ones.
It’s not just the bugs that bother me though, it is the way the company treats its customers and reacts to those issues.
Also, last year Yoast was bought by the same company that owns EIG. If you are familiar with EIG, you will know why that may be a concern.
SEOPress basically does everything Yoast does, but is less bloated and has never F’d up one of my sites.
Monday - Although not directly an SEO tool, this is the other tool I log into every single day. I often get asked how I keep on top of everything and manage clients without anything falling through the cracks. This is how. There are plenty of similar tools out there, and even if you are working solo, I would recommend using one. ClickUp and Asana would be my next choices.