You should not have to choose between good writing tools and your privacy. Charm is everything Grammarly does, without the subscription and without the cloud.
macOS has had a built-in autocorrect for years. Most writers who rely on it know the problem: it is unreliable, frequently makes the wrong call, and sometimes makes your writing worse than if you had typed freely. The obvious alternative is Grammarly, which works well but carries a subscription cost and routes every keystroke through the cloud. Theodore Harding did not find either of those acceptable, so he built Charm.
Charm is a native macOS menu bar app that sits quietly in the background and corrects spelling, fixes grammar, and predicts the next word as you type - across every app on your Mac. Not just in a browser tab. Not just in one writing tool. Everywhere.
On-Device, One Price
The core technical decision in Charm is that everything runs locally. Harding chose to build around on-device language models - specifically Gemma 2 2B and Qwen 2.5 3B - that run entirely on the user's own hardware. No text leaves the computer. That choice took the better part of a year of solo development to get right: making local inference fast enough, accurate enough, and light enough to run quietly in the background without interrupting the writing process.
The result is a $9.99 one-time purchase. No recurring fee, no account required, no server processing your drafts.
That combination - system-wide correction, on-device processing, single payment - is a direct answer to the trade-offs that have defined the writing tool space for years. Grammarly users pay $12 to $30 per month depending on the plan, and everything they write passes through Grammarly's infrastructure. Charm's entire pitch is that neither of those things should be necessary.
Who It's For
Harding describes the target user broadly: anyone who types on a Mac and wants to write with confidence. But a few specific groups stand out in how he talks about the product.
People whose first language is not English benefit from continuous, quiet correction that does not interrupt their flow. People with dyslexia or other challenges with spelling find the same value - Charm corrects as they go, without flagging or drawing attention to errors, so they can write freely and trust the output. And people who move across many different apps throughout the day - writers, operators, customer support teams - benefit from correction that follows them instead of being confined to a single interface.
The menu bar format keeps the footprint small. It runs in the background, activates when needed, and does not add another window or panel to manage.
Charm is available now for macOS at $9.99 as a one-time purchase from theodorehq.com.
