I am using Hemingway Editor for a few months now and found it useful, especially for improving readability grade, making content voice active, craft content within character limits (especially meta descriptions and SEO titles), and write in a focused way.
The online version is free. You can buy offline app for Windows PC or MacBook for a little onetime fee of US$ 19.99. If you are looking for an offline editor for improved writing, you will be impressed by Hemingway Editor.
Make your writing bold and clear