Your prompter, at your side. Local, private, yours.
When someone puts you on the spot, you're not blanking. You're reading your line.
Promptside is the prompter at your side: it listens to your call and feeds you your line — a rolling summary, the things that need your attention, and what you could say next.
Your audio is transcribed on your Mac and never uploaded. The summaries go straight from your machine to your own AI key — never through us. Free while in beta; buy it once when it's solid. No subscription.
Download for Mac — free beta How it stays private ↓
macOS 15+ · Apple silicon·signed & notarized·auto-updates·bring your own AI key (Anthropic, OpenAI, or Gemini)
The problem
You know the feeling.
"So — what do you think?"
Someone turns to you in the meeting and the last ten minutes have gone blurry. You were half-listening, half-typing notes, and now the room is waiting.
Forty minutes into the Zoom…
…and you've lost the thread of what you already agreed to. What was the number? What did they actually ask for? You're nodding along, hoping it comes back.
The bot in the room.
The meeting copilot everyone uses joins as a bot, records the room, and ships every word you say to someone else's cloud. You just clicked "allow" because the meeting was starting.
None of these are skill problems. They're working-memory problems. Live conversation moves faster than any one person can hold in their head — and the tools built to help mostly help themselves to your data.
The mechanism
How Promptside actually works
Promptside is a small floating overlay that sits on top of whatever you're doing. It does four things, in this order:
It listens — and transcribes your audio on your Mac.
Promptside captures both sides of the conversation (your mic and the call's system audio) and transcribes them locally using WhisperKit on the Apple Neural Engine. Your audio is never uploaded — there's no server for it to go to. It's transcribed in-process, on your machine, and the audio stays there.
It keeps a rolling summary and pulls out what's for you.
As the conversation runs, Promptside maintains a continuously-updated summary and highlights the things that actually need your attention — a question aimed at you, an action item, a claim worth checking.
To do this it sends the transcript text — not your audio — to the AI through your own key: Anthropic, OpenAI, or Google Gemini, your choice. That call goes straight from your Mac to the provider under your account; it never passes through our servers. You glance, you catch up, you're back in the room.
It feeds you your line.
When you need it, Promptside suggests what you could say next — steered by a persona you chose. It doesn't talk for you. It's the prompter at your side: it feeds you the line; you decide what to say and you say it. You're the one in the conversation. Promptside is the voice in your eyeline, not your mouth.
You can also type to steer it live — "focus on the pricing question," "summarize the last five minutes" — and it adjusts.
You cast the role — personas are just files you own.
A persona is a Markdown file: the scene Promptside is playing, the tone it takes, what it knows going in. Interview rehearsal, a long client call, a watch-along — you write the persona, edit it, keep it, version-control it if you want. It lives in a folder on your Mac. No account, no cloud lock-in, no one else's idea of who you are.
And because the overlay uses sharingType = .none, your notes
stay yours: when you share your screen in your meeting,
your private summary isn't on it. It's a sticky-note on your own monitor —
there for you, not pasted into the slides for everyone else to read over
your shoulder.
The proof
Radical transparency, instead of testimonials.
Promptside is new. We're not going to fake a wall of testimonials, and we're not going to quote a fictional Head of Sales. Here's the proof instead: the design.
Local-by-design is the proof.
Your audio is transcribed on the Neural Engine, in-process — there's no server for it to go to, so it can't be uploaded. The only thing that leaves your Mac is transcript text, and it goes to your AI key, not to us. The privacy claim isn't a policy you have to trust; it's an architecture you can inspect.
You own the binary and your files.
It's a signed, notarized Mac app and a folder of Markdown personas. Nothing about Promptside is rented or revocable. When there are real users with real results, they'll go here — named, specific, checkable. Until then, we'd rather show you exactly what it does than tell you what to feel.
Objections
The real ones, answered plainly.
"Where do you draw the line on using this?"
Plainly: we don't build Promptside for proctored, monitored, or consent-required settings — that's not a disclaimer, it's a design constraint. If the person across from you would object to you using it, don't use it there.
Promptside is built for the rooms that are already yours: your own meetings and calls, solo rehearsal before a high-stakes conversation, learning, watch-alongs. It's the prompter at your side — it feeds you your line, you do the talking, in settings where reading your own notes is fair. Think teleprompter, not ghostwriter: newscasters and CEOs read from teleprompters in plain sight.
"Why pay for this when free OSS clones do the same overlay?"
Fair question — and the honest answer isn't "ours is invisible." Theirs are too. The difference is what you're actually getting. Those are scripts you babysit: clone the repo, wire up your own keys, fight the build, hope the audio capture still works after the next macOS update.
Promptside is a finished product you own — Developer-ID signed and notarized, so it launches without a Gatekeeper fight; auto-updating; a real persona system, not a config file; the craft and polish of something built to be used daily, not demoed once. And it's trust-tech, not a stealth toy: the whole product is designed around where your data goes and where it's fair to use.
If you'd rather run the script, the script is free — we're not pretending otherwise.
"Does my audio leave my Mac?"
No — your audio doesn't. Transcription happens on-device with WhisperKit on the Neural Engine; there's no server to upload audio to.
The one thing that does leave is transcript text, sent to generate the rolling summary and suggestions — and it goes through your own AI key, straight from your Mac to the provider under your account, never through us. So: audio stays put, transcript text goes to your key, nothing routes through our servers.
"Why bring my own key?"
Because it's your data and your account. BYOK means the inference runs on your own key — Anthropic, OpenAI, or Gemini — billed to you at the provider's rates, no markup from us, no middleman holding your transcripts.
That inference is a real cost (~$4–16/hour of active use; see Pricing) — we're not hiding it. The difference from the cloud tools is that you pay the provider directly, at cost, on your own account, instead of paying a vendor a margin on top and handing them your transcripts. You control the spend; we never touch it.
"Mac only? And why a DMG instead of the App Store?"
Honest answer: the App Store requires the App Sandbox, and the sandbox is hostile to the two things that make Promptside work — capturing system audio and hiding the overlay from screen-share. Apps like Granola, Cluely, and superwhisper all ship outside the App Store for the same reason.
So Promptside is a Developer-ID-signed, notarized DMG: a real, verified Mac app you download and run, not a sideloaded mystery. Mac-only, for now, because it's built natively on macOS audio and overlay APIs — no Electron, no compromise.
Pricing
Free while in beta. Then buy Promptside once — $99. The app is yours; no subscription to us, ever.
Right now Promptside is in a free beta while we iron it out with early users — the full app, no time limit, no card. When it's solid, the price is $99, one-time, for the app. There's no monthly fee to us, and Promptside keeps working even if we disappear.
The one ongoing cost is inference, and it runs on your own AI key — billed by the provider, directly to you, at cost. We take no margin on it. Let's be straight about that cost, because it's real: with the key active, Promptside calls the AI roughly every few seconds, so inference runs about $4–16 per hour of active use depending on the model you choose and how much is actually being said. You control it — pause Promptside when you're not in a conversation, pick a cheaper model, and remember it's metered by speech, not by the clock. We're not going to pretend it's "a few dollars."
| Promptside | Cloud copilots | |
|---|---|---|
| What you pay us | Free in beta · $99 once after | $55–$299 / month, forever |
| Inference | your own AI key, at cost, no markup | resold to you at a margin, baked into the sub |
| Your audio | stays on your Mac | uploaded to their cloud |
| Your personas | Markdown files you own | account-bound, cloud-locked |
| Your account | your key, your provider bill, your data | their servers, their terms |
| If you stop paying us | you keep it forever | it stops working |
What the $99 will buy you isn't a lower total bill than a cloud subscription — for a heavy user it may not be. It's a different deal: no markup — you pay the provider at cost, not a reseller's margin. You own it — once, forever, even if we vanish. You control the spend — pause when idle, choose a cheaper model. Your data, your account — transcript text goes to your key, never our servers.
You're not renting your second brain by the month. You own it.
Use cases
Three scenes you cast.
The long Zoom — your own meeting.
Two hours, eleven people, three decisions you're accountable for. Promptside holds the rolling summary so when you tune back in, you're caught up in a glance — and when someone asks "what's your take?", the last ten minutes are right there, not gone. This is the room Promptside is built for: a meeting that's already yours.
The watch-along.
A documentary, a talk, a match. Cast a persona — the film buff, the historian, the stats nerd — and Promptside feeds you context, trivia, and fact-checks in real time, in the voice you chose. A second brain for the things you watch, not just the things you work on.
Interview rehearsal — solo, beforehand.
Write a persona for the role and the company, then run a mock conversation by yourself, before the day — Promptside plays the interviewer, keeps the thread, and lets you practice answering out loud until it's in your body. You walk in having already had the conversation once. To be clear: this is rehearsal you do alone in advance — Promptside isn't built for the room where someone would object to it.
Your prompter is waiting.
Your audio transcribed on your Mac, never uploaded. Summaries that go straight from your machine to your own AI key — never through us. Personas you own as files. Free while in beta, one $99 license when it's solid. No subscription, no bot in the room.
macOS · Developer-ID signed & notarized·bring your own AI key·your audio stays on your Mac