I've had the Hemingway Editor desktop app open in my dock for three years, and it's witnessed every important email, landing page, and client proposal I've written. It's not sexy, it's definitely not AI-powered despite what the marketing suggests, and it will absolutely hurt your feelings the first time you paste in something you thought was well-written—but it works.
Buy the desktop app if you regularly write emails, marketing copy, or business documents and tend toward complexity—it's the best $20 you'll spend on writing improvement. Skip it if you need advanced AI features, write creatively, or only edit documents once in a blue moon (just use the free version). This tool won't write for you, but it will ruthlessly show you where you're losing your reader's attention.