Grammarly is good at what it's built for: catching mistakes as you type, in real time, with a decade of tuning behind it. If that's all you need, it's a solid choice and this post won't try to talk you out of it.
But grammar checking is one job. If what you actually want most of the time is to rewrite something — shorter, more formal, translated, in your own specific voice — that's a different job, and it's the one KeyShift is built around.
One mechanism, not one integration per app
Grammarly reaches your text through its own extension or app for each place you write: the browser extension for web fields, a desktop app for some native apps, separate integrations elsewhere. Every additional place you want it to work is its own integration to get right.
KeyShift works through a single mechanism at the OS level: select text anywhere, or type into whatever field you're in, and it's there. Word, Outlook, Slack, a ticket in your support tool, a field in a CRM nobody bothered to build an integration for. No per-app setup.
Grammar and typos, plus everything after that
Fixing grammar is one action among several, not the whole product:
- Fix grammar and typos — the baseline, same job Grammarly does
- Translate — into any language you can name, not just the ones in a menu
- Rewrite the tone — more professional, more casual, shorter, more direct
- Your own custom prompt — write the instruction once ("always keep it under three sentences and never use an exclamation mark"), and every result follows it automatically, instead of you re-explaining your voice every time
That last one is the real difference. Grammarly's suggestions come from Grammarly's model of good writing. A custom prompt is yours.
How you use it
Select existing text and press Ctrl+Shift+A to pick an action, or skip selecting anything and just type. Write normally, then right after it, type keyshift followed by what you want, and press space twice:
so sorry for the late reply been swamped this week keyshift make this more professional
Double space, and the sentence becomes the polished version, replaced in the same field you were already typing in.
Your own AI, your own cost
Grammarly runs its own engine, on its own terms. KeyShift lets you bring your own key, OpenAI, Claude, Gemini, or a local model if you'd rather nothing leave your machine. See the BYOK guide for the two-minute setup.
Every plan, including Free, includes grammar fixing, tone rewrites, and translation. Try it free with 25 credits a month, or see pricing if you already know you'll want more.