Tetr
Write, circle, ask. Your handwriting is the prompt and your page is the answer.
Handwritten notes that live in your folder as plain PNG and Markdown files — now with AI that answers on the page.
Join the 1.2 beta on TestFlight free · iPad and iPhoneOr get the current release: Tetr 1.0 on the App Store, $3.99 once, no subscription.
Version 1.2 — in public beta now
The note is the UI
Circle what you wrote, tap Ask, and an AI model — or an agent of your own — answers right there, in ink or as a drawing. The notebook becomes the ledger of your work.
Talk to any service by writing
Your handwriting and drawings are the prompt. A hosted model, Apple Intelligence, or an agent you run yourself answers on your page.
The page is the ledger
Every ask and answer stays on the page, and as plain files next to it. Nothing vanishes into a chat history.
Come back and continue
Open a note weeks later, circle the answer, ask the next question.
What that looks like
A note per job, a prompt per note
Add a provider more than once, each with its own instructions, and each note remembers which one it uses. The translation notebook answers in Armenian; the expenses notebook tallies a table.
A running plan you never leave
Keep a project on one page. Circle the last lines and ask "what's next?". Every step stays there.
Your own agents, by hand
Point a note at any OpenAI-compatible endpoint. A task handed off by hand, the result drawn back in.
How an ask works
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1
Select
Draw a loop or a rectangle around any part of the page.
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2
Say what you want
Type or dictate a short instruction, or skip it.
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3
Ask
The answer lands below the selection, or in place inside the box you drew.
Quick ask
One tap asks about everything you wrote since the last answer. No selecting.
Several asks at once
Ask about different parts in parallel, switch notes, come back. Each answer shows its progress on the page.
Your model, your key
Anthropic, OpenAI, OpenRouter, Gemini, Groq, Mistral, DeepSeek, xAI, Ollama, LM Studio, and more. Keys stay in the Keychain.
On device
Apple Intelligence on a supported iPad. Nothing leaves the device.
Tetr AI, on by default
Works out of the box with free turns to start, then packs of turns. No subscription.
Text boxes and photos
Draw a rectangle and type into it, or drop in a photo.
Tetr on iPhone
One app, one purchase. Finger on the phone, Pencil on the iPad, same notes.
Opt-in
No model configured, no network requests. When you ask, only the selection goes to the provider you chose.
Get the beta
The 1.2 beta is open on TestFlight for iPad and iPhone. Install Apple's free TestFlight app, then open the link.
- Tetr AI comes with 10 free turns. Packs bought in the beta are free too, up to 500 turns per wallet, so please try a purchase.
- Bring your own API key or use Apple Intelligence if you prefer.
- Tell us what breaks: support@resonator.am, or the feedback button in TestFlight.
Why Tetr
Write naturally
An endless canvas on Apple's own ink engine: pressure, tilt, palm rejection.
Your files, your folder
Notes auto-save as PNG into any iCloud Drive folder. No lock-in.
Read it as text
On-device recognition writes a Markdown transcript next to every note.
Still fully editable
Each PNG carries its stroke data, so Tetr reopens it as live ink.
Simple on purpose
Open, write, done. Your last note reopens on launch.
Private by design
No account, no analytics, no tracking. Nothing leaves your storage unless you ask.
What a note looks like on disk
Ordinary files in the folder you picked. Anything can read them.
Note.png |
A normal image of the page, carrying the stroke data for editable ink. |
|---|---|
Note.md |
The on-device transcript, as Markdown. |
Note.ttl 1.2 |
RDF sidecar: strokes, drawings with SVG source, transcript, chosen model. Vocabulary. |
agent/Note/ 1.2 |
The AI conversation, turn by turn. |
Support
Questions, bugs, ideas? A human reads every message.