AI writing assistant for Windows
Stop switching to ChatGPT. Select text, press a shortcut, and Keystro corrects, rewrites, translates, or summarizes it — right in the app you're already using.
Free plan · No setup · 30s install
60-second product demo
From the ChatGPT copy-paste detour to a two-second correction in the app where you already work — Correct, Draft Email, and Ask follow the same pattern.
What you'll see
The copy-paste detour
Tab to ChatGPT
3sLeave your current app
Paste your text
2sMove private context elsewhere
Type your prompt
10sThink about instructions again
Wait for response
8sLose your writing rhythm
Copy the result
3sSwitch hands, switch context
Tab back to your app
3sFind your original cursor
Paste & reformat
15s+Fix spacing, bullets, tone
The native shortcut path
Select your text
0sStay exactly where you are writing
Press Ctrl+Shift+C
0.5sKeystro reads the selection instantly
Done — text replaced
1.2sCorrection appears in the same app
Do the math
A normal day of emails, Slack, notes, and reports.
Works inside every app you already use
Four ways Keystro fits into the writing you already do.
You type fast. Keystro fixes.
Typo-filled email → client-ready in one shortcut
< 2 secondsSelect the whole thread, add //summarize email thread. Key points, decisions, action items.
Long thread → bullets, decisions, and next steps
Saves minutes per threadTake notes raw during the call. Add //format as meeting minutes. Structured output in seconds.
Rough notes → structured minutes
From raw to report-readyType casual and fast. Correct keeps your tone — just cleans typos and grammar. You never look sloppy again.
Casual chat → same voice, zero typos
Keeps your voicehey, could we reschdule the meeting on thursdey? i had a conflit with another client
Hey, could we reschedule the meeting on Thursday? I had a conflict with another client.
Same shortcut, every workflow
Each row above is a real pattern: select your text, press the chord, and the result replaces your selection — no new window, no copy-paste.
No window. No copy-paste. No tab-switch.
Three things change the day you stop switching to ChatGPT to deal with text.
No copy-paste, no tab-switch, no re-prompting. The action happens where you already work — giving you back around 70 hours a year.
Your eyes never leave the app you are writing in. No second window stealing your attention, no rhythm to rebuild after every detour.
Every email, message, and note goes out clean, clear, and on-brand — in your own voice, even when the language is not your first.
Each shortcut is purpose-built for a specific need. No generic prompts. Targeted, instant, in place.
Fix grammar, spelling, and structure instantly. Add // at the end for any custom instruction.
Transform any draft into a polished professional email that keeps your voice.
Open a prompt on your selection and ask anything — translate, rewrite, summarize, expand, Q&A.
Add // followed by any instruction after your selection. Translate, shorten, change tone, expand — the same Correct shortcut does it all.
Bonjour, je voudrais savoir si le projet avance bien.
//translate to English, make it more formal
Dear colleague, I would like to inquire about the current progress of the project.
Add // plus your instruction after the selection, then press Correct — translate, change tone, shorten, or expand without leaving the app.
Works in any language, with any instruction. Translation, tone change, shortening, expansion — all through //.
ChatGPT starts from a blank slate every time. Keystro knows your words, your role, and how you write — on every shortcut, automatically.
Teach Keystro your acronyms, client names, and product names. It keeps them exactly as written — never autocorrected, never translated — on every single action.
the linkedin roi on our saas kpis
the LinkedIn ROI on our SaaS KPIs
Tell Keystro who you are — once. Every draft and rewrite then writes as you, not about you.
Keystro factors all of it into every draft and rewrite — so the result reads like you wrote it, in your tone and your level of detail, not like a generic AI.
The more you use Keystro, the more it sounds like you. That is the one thing a blank chat window can never copy.
If your job is writing, Keystro is your unfair advantage.
You write client proposals, meeting notes, and reports daily. Your reputation rides on every word.
You send dozens of outreach messages every week across email, LinkedIn, Slack. Speed and clarity win deals.
You draft memos, reports, and updates. Polish matters. Sometimes English isn't your first language.
Zero-content-storage architecture. Your text flows through AI, returns corrected, and is immediately discarded — by design.
Keystro uses your name and email address only to create and secure your account through Clerk. It does not request access to Gmail, Google Drive, Google Calendar, Outlook, OneDrive, or your files. See our Privacy Policy.
Tokens encrypted via Windows DPAPI. No text saved locally.
Helmet headers, rate-limited, JWT auth, zero content logging.
Processed in memory. Not stored. Not used for training.
store: false on every AI call. OpenAI is contractually prevented from storing, logging, or training on your text.
We track usage metadata only (action type, character count). Your actual text never touches our database.
Auth tokens encrypted on your machine via Windows DPAPI. Your credentials never leave your device.
Transparent by design.
Defense in depth.
Security questions from your IT or security team? Contact us
Start free and make Keystro a reflex. Upgrade when you can't imagine working without it. Cancel anytime.
Build the habit. No card required.
Enough to make Ctrl+Shift+C a reflex
Get Started FreeFor professionals who write all day.
Everything you need for daily work
Start ProEverything in Free, plus:
For power users who live in their inbox.
Maximum volume & personalization
Go Pro+Everything in Pro, plus:
Prices in EUR. VAT not applicable (art. 293 B CGI) — the price you see is the price you pay. Free plan needs no credit card. Cancel anytime.
| Feature | Free | Pro | Pro+ |
|---|---|---|---|
| Usage | |||
| AI requests / month | 50 | 1,000 | 3,000 |
| Correct, Draft Email, Ask | |||
| Inline // instructions | |||
| Personalization | |||
| My Prompts library | 5 | 20 | 50 |
| Personal Vocabulary terms | 25 | 200 | 500 |
| Profile-aware AI (role & industry) | |||
| Email signature on drafts | |||
| Privacy & security | |||
| Zero Data Retention (store: false) | |||
| No text content ever stored | |||
| Encrypted local tokens (DPAPI) | |||
| GDPR export & delete | |||
| Support | |||
| Community support | |||
| Priority email support | — | ||
Privacy isn't a paid add-on — every plan, including Free, gets the same security posture. See how we protect your text →
50 free requests every month, forever. No credit card.
Get Keystro for WindowsWindows 10/11 · Install in 60 seconds · Cancel anytime