The Platen typewriter app turns the iPhone Duo into a sheet of textured paper with mechanical key sounds, and every note you write in it stops at 3,000 characters. That limit is the same in the free version and in the paid Platen Studio, so Platen suits letters and short entries rather than long drafts.
Platen is free on the App Store and now runs on iPad as well as iPhone. It joins Halfpage, Post Club, Foldtype and Foldwriter among typewriter apps for the iPhone Duo, and it keeps everything you type in a Box of filed letters with search and optional iCloud sync.
Platen typewriter app caps each note
Spaces and line breaks count toward the 3,000-character limit on each Platen note, and a character count sits on the page as you type. The free version gives you three active notes, the original writing setup and two charms, while Platen Studio adds more notes without raising the limit on each one.
Your letters go into the Box, where you can file them behind named dividers while you write and mark them with flower tabs. Search finds any note, and the Home screen groups your notes by month. Recently Deleted brings back a note you removed, and you can export a backup or turn on iCloud sync with your Apple Account.
You can pin one letter to the Lock Screen and the Dynamic Island, then tap it to go straight back to the page. A Cross out on Lock Screen switch strikes through the words when you want privacy.
Sharing turns your page into a picture, including one sized for an Instagram Story. Platen Studio adds print-ready A4, US Letter and A5 sheets laid out like a typed letter.
Platen changes with each fold
Platen moves its page and keys for each pose of the iPhone Duo, so the same note works whether the phone is open, standing or closed. The capsule that follows your words along the rail also works as a button, and tapping it shows or hides the keyboard.
- Half open, your Box and Studio sit on the left and the page sits on the right
- Standing like a tent, the page is on top and the keys are underneath
- Fully open, the whole sheet lies on a paper desk
- Closed, the page fills the front screen edge to edge
On iPad, Platen gives you a full-size sheet that you type on with a keyboard, upright or sideways. When a hardware keyboard is connected, a note is ready to type the moment you open it and the on-screen keys step aside. You need iOS 18 or iPadOS 18 or later to install Platen.
A new typewriter: ~$270. A restored Olivetti: up to ~$1,000.
Your iPhone Duo: already in your pocket ⌨️Platen turns your iPhone/iPad into a typewriter. Fold it like a laptop: paper up top, lever keys below. Clack, clack, ding.
Public beta is live. Follow + comment “TestFlight” and I’ll DM you the link 👇
— 0xProbability (@0xProbabillity) November 3, 2026
Ink, sound and the night lamp
Platen prints your letters in imperfect ink on flat or curved paper, and you can choose Fresh, Seasoned, Worn or Clean ink. The worn ribbon prints Chinese, Japanese and Korean characters unevenly, the same way it prints English.
When you make a mistake, Platen can keep it as a crossed-out letter or erase it cleanly. Turning off the Autocorrect switch keeps every keystroke as you struck it, and you can choose to hear the typewriter even when your phone is in silent mode.
Long-press the capsule to write by lamplight, then change the lamp’s warmth, intensity and beam. Platen also offers 120 first lines for the days you do not know how to start a letter.
Platen Studio costs $8.99
Platen Studio is a one-time $8.99 purchase with no subscription, and it includes every pack and all future Studio features. You can try every capsule and charm before you pay.
The packs are also sold on their own. Charms & Pegboard and Crafts of the World cost $2.99 each, and the Halloween Pack and Día de Muertos cost $1.99 each. A Bats & spiders switch lets you keep the Halloween capsule without bats and spiders crossing your paper.
Foldwriter costs $1.99, Halfpage $2.99 and Post Club $4.99 for the whole app, so Platen Studio costs more than buying any of those three apps outright. A charm or capsule made just for you costs $29.99 through Apple, and you then email your idea to the developer with your receipt code.
