SEMrush Suite for Content Writers:
Keyword Magic Tool narrows down your keyword search and helps you find the best keywords to base your text on.
Topic Research helps you discover new content ideas and finds out what people are searching for about your topic (topics and questions).
Organic Research shows you your top-performing dbtodata competitors, so you can learn from them how to rank higher (and outperform them!).
SEO Writing Assistant will help you optimize your content based on your top 10 competitors' rankings on Google. Download the add-on to check if what you are writing is SEO-friendly and the originality of your content, or to improve the readability of your text and the consistency of your "Tone of voice" when you write.
On-Page SEO Checker can help you track your results after publishing your content; you will get SEO tips to improve your rankings.
Other useful tools for those who write online:
Google Search Console and Google Analytics for analyzing the performance of your pages. Check how your website is performing, what you might need to work on, and what can be improved based on user behavior on your pages.
Google Trends is a tool that allows you to discover which topics are trending, also useful for keyword research (it shows search volumes and related keywords to refer to).
Hemingway App was created to improve your English writing, but some features can also help you if you write in Italian. The editor will help you improve readability by checking your text for sentences that are too long or complicated.
AlsoAsked.com shows you questions that are being asked about your chosen topic.
Typeform / Google Forms to create surveys to collect data.
Short URL / Bitly to shorten your page URL, track link clicks and social shares.
Canva helps you create custom images, social visuals, animations and infographics for your website, articles and social accounts.
Unsplash / Flickr / Pixabay provide you with high-quality, royalty-free images.
Seomofo shows you a preview of your snippet in the SERP.
Google Docs and Google Sheets are great for improving collaboration within a team because they allow each member to make real-time changes to a text and track content planning.