Whether you need to craft a punchy email, a concisely worded cover letter, or a clever Twitter update, it can be difficult to identify unnecessary words in your own writing. Fortunately, if you’re struggling to fine tune your writing or reduce your resume to a single page, there’s a web app that can help.

Expresso is a free app that points out style issues in blocks of text. Lifehacker reports that the app is useful for identifying common writing issues like filler words, use of passive voice, and weak verbs. Simply copy and paste the text you’re working on into the app—or write directly in the text field—and let Expresso analyze your writing.

While Expresso is useful for editing individual texts, its aim is actually much broader. According to the Expresso website, the goal is to teach effective writing techniques using concrete examples. “While good writing style is hard to master, there are several simple yet powerful techniques which many writing guides and coaches focus on,” the website explains. “Expresso teaches these techniques by applying them directly to your writing.”

The app is also useful for analyzing the writing of others. Try typing a passage from your favorite book into Expresso, or compare the styles of a range of authors, to identify what makes their writing so powerful. Of course, keep in mind that while Expresso can help you better understand writing, its metrics should be just one tool in your writing arsenal. “Writing metrics employed by Expresso can be powerful but they are not a 'magic bullet,'” the website notes. “Good writing style remains an art, not a science.”