Tomorrow we launch RewriteCmd on Product Hunt. Before we do, we want to tell you why this thing exists.
It started with a moment most of you will recognize.
The Tab That Broke the Flow
Late last year, one of us was writing a follow-up email to a client. The stakes were medium -- not life-changing, but the kind of email where tone matters. Friendly but not casual. Clear but not blunt.
The first draft read fine. Almost fine. The second paragraph was too stiff. So -- muscle memory at this point -- Cmd-C, open a new tab, navigate to ChatGPT, type "rewrite this to sound warmer but still professional," paste the paragraph, hit enter, wait, read the output, Cmd-C again, switch back to Mail, find the right spot, Cmd-V.
Total time: maybe forty-five seconds. Total focus destroyed: about fifteen minutes.
That round-trip -- copy, switch, prompt, wait, copy, switch back, paste -- is the tax that every professional who uses AI for writing pays dozens of times a day. The AI itself is remarkable. The workflow around it is absurd.
We knew we weren't the only ones feeling it. And we knew the fix wasn't another AI chat window or another browser extension. The fix had to be invisible.
The Idea: What If AI Just Worked Where You Write?
The core insight was simple. You shouldn't have to go to AI. AI should come to you, right where your cursor already is.
Select text. Hit a shortcut. The text gets better. That's it.
No new tab. No new app. No paste-back step. The rewrite happens inline, in the app you're already working in, and you keep moving.
We wanted it to work in Mail and Slack and Notion and VS Code and LinkedIn and every other app where professionals type words they care about. Not through a plugin for each app. Not through a browser extension that breaks on the next Chrome update. At the system level.
On macOS, that meant building a native app.
Why Native macOS -- And Why It Had to Be Swift
We could have shipped an Electron app in a month. Wrap a web view, bundle Chromium, call it a desktop app. That's what most writing tools do.
We chose not to.
Electron apps consume 200 to 500 MB of RAM just sitting in your dock. They don't feel like Mac software. They can't access macOS accessibility APIs cleanly. They're web pages pretending to be native apps, and your Mac knows it.
RewriteCmd is built in pure Swift. It sits in your menu bar. It uses macOS accessibility APIs to read and replace selected text in any application -- the same system-level APIs that power features like VoiceOver and text-to-speech. That's why it works everywhere without needing a plugin or extension for each app.
The result is an app that launches instantly, uses negligible resources, and feels like part of the operating system. Because on a technical level, it is.
If you care about your Mac running clean -- if you're the kind of person who notices when an app is Electron -- this matters.
The BYOK Decision: Your Key, Your Privacy, Your Choice
Early on we faced a fork in the road that defines almost every AI-powered product: do we proxy AI requests through our own servers, or let users connect directly to their preferred AI provider?
Proxying is the standard playbook. It lets you mark up API costs, lock users into your pricing, and collect data to "improve the product." Most AI writing tools work this way. You pay $20 a month and have no idea which model you're using, what it costs per request, or where your text goes between your app and the AI.
We went the other direction. RewriteCmd is BYOK -- bring your own key. You plug in your API key for Claude, OpenAI, or Mistral, and your text goes directly from your Mac to the AI provider. Nothing passes through our servers. Nothing is stored. Nothing is logged.
Three things drove this decision.
Privacy is non-negotiable. Professionals rewrite sensitive text. Client emails. Internal strategy docs. HR communications. Legal responses. That text should never touch a server you didn't choose.
Model choice should be yours. Claude 4.5 handles nuance differently than GPT-4o. Mistral is fast and cheap for quick cleanups. The right model depends on the task. You shouldn't be locked into whatever model a SaaS vendor negotiated a volume deal on.
Cost transparency matters. With BYOK, you see exactly what each rewrite costs -- fractions of a cent for most operations. No flat subscription fee subsidizing features you don't use.
If you already have an API key from building side projects or using Copilot at work, you're set up in under a minute.
Who RewriteCmd Is For
We built RewriteCmd for people who write as part of their job but don't think of themselves as writers.
The marketing lead who rewrites campaign briefs twelve times before they land. The developer who spends more time on documentation and PR descriptions than they'd like to admit. The support manager who crafts fifty responses a day and needs each one to hit the right tone. The ops person drafting vendor emails, internal memos, status updates -- the invisible writing that keeps companies running.
These people don't need a full writing suite. They don't need a grammar checker that underlines every sentence with green squiggles. They need a fast, invisible tool that makes their existing text better without pulling them out of the app they're working in.
That's a narrow wedge. We chose it deliberately.
What RewriteCmd Actually Does
You select text in any macOS app. You press Cmd+Shift+R. RewriteCmd reads the selection, sends it to your configured AI model with context about what kind of improvement you want, and replaces the selected text with the result. In place. No clipboard juggling. No window switching.
The default rewrite makes text clearer and more professional. But you can customize prompts for specific use cases -- "make this more concise," "translate to French," "rewrite for a technical audience," "make this friendlier."
It works in Mail, Slack, Notion, Google Docs (in Chrome), VS Code, Obsidian, Bear, LinkedIn, Twitter -- anywhere you can select text on macOS.
The app lives in your menu bar. It uses almost no memory. You forget it's there until you need it, and then it's one shortcut away.
What We Learned Building It
Building a system-level text manipulation tool on macOS is harder than it sounds. Accessibility APIs behave differently across apps. Some apps use standard text fields. Others use custom rendering. Web apps in browsers add another layer of complexity.
We spent months on edge cases. Getting paste-back to work cleanly in Electron-based apps (ironic, yes). Handling rich text without destroying formatting. Making the shortcut registration work alongside apps that aggressively claim global shortcuts.
The result is something that just works. That "just" represents thousands of hours of engineering work. But that's the point -- the best tools are the ones you don't notice.
Why Product Hunt, Why Now
RewriteCmd has been in beta with a small group of users since early 2026. The feedback has been consistent: people try it once, and the copy-paste-to-ChatGPT workflow immediately feels broken by comparison.
We're launching on Product Hunt on April 8 because PH is where Mac-first, productivity-obsessed builders discover new tools. Our users are there. You're probably there.
RewriteCmd is free to try -- the free tier gives you a feel for inline rewriting without entering a credit card. Pro unlocks custom prompts, unlimited rewrites, and multi-model support for $10 a month. Business adds team management and shared prompt libraries.
Join Us Tomorrow
If the copy-paste-to-ChatGPT loop has ever broken your flow, we built RewriteCmd for you.
We launch on Product Hunt on April 8. Your upvote helps other professionals find a better way to write.