I like these two tools as they are not only effective they are also easy to use. First is Grammarly, from the name itself it is a grammar checker. Grammarly can be handy especially with those little things but can majorly affect how you can be perceived because of your spelling and grammar.
The second tool is Hemingway app , free online and Desktop app is available for one- time fee of $19.99. The function is derived from the style of the name itself Ernest Hemingway, best known for his style of bringing difficult sentences into simple and understandable terms. Novel masterpieces that can be easily understood by doctors and farmers alike. It promises to make your content "bold and clear". It suggests eliminating any wordy sentences and make it simple to the delight of your readers.
Try it yourself today and see how simple it is. It can really improve your writing.