Sideproof: Private Messaging

Read and write private messages wherever people sit close by: on the bus, at work, in a waiting room. With Sideproof: Private Messaging, your text appears in dim red on pure black, so it's clear when you look straight at your iPhone and harder to read for anyone looking from the side.

It's based on a well-known accessibility trick, but works only inside the app, so the rest of your iPhone stays exactly as it is.

Private messages in iMessage

- Tap + in a conversation, choose Sideproof and write in the same dim view.

- Your message arrives as a locked "Private message" bubble. Its text never shows in the bubble, in notifications or in the conversation list.

- Hold to read: the text shows only while your finger is down. Prefer tapping? Switch to Tap mode.

- Optional line-by-line reveal shows just a band of text above your finger.

- Auto-hide after 5, 10 or 30 seconds, or turn on Read once and messages expire after their first reading.

- Your recipient needs Sideproof: Private Messaging on their iPhone. Without it, or on a Mac, they see only a "Private message" bubble.

Private images for any chat app

- Write in the app and your message becomes an image in the same dim style, ready to share through any chat app that accepts photos.

- Your recipient doesn't need the app, or even an iPhone.

- Long messages are split across numbered images instead of shrinking the text.

- Images carry no location or device details, and the app deletes its copy after sharing. Save Image stays hidden unless you allow it, because iPhone search can find words in saved photos.

- Built-in tips: send to one person, not a story, use View once where your chat app offers it, and send as a file for the sharpest result.

Tuned to your eyes and your room

- A short calibration helps you dim the text until it's just comfortable, choose a colour and check it from the side with a friend.

- Bright, Indoors and Dark room presets, plus hue, intensity and white point sliders with a live preview.

- Red by default, with Amber and Grey for anyone who finds red hard to see.

- The app can also lower screen brightness while it's open, and restores it when you leave.

- Set it once: the app and the iMessage app share the same settings.

Protection on every screen

- The screen goes black the instant you switch apps, open Control Centre or Notification Centre, or take a call.

- Content is hidden while your screen is recorded or mirrored.

- Keyboard suggestions and Writing Tools are off by default, so your words don't pop up above the keyboard.

- Add a privacy screen protector for one more layer: the viewing angle gets even narrower and the text even harder to read from the side.

Accessibility

- With VoiceOver, double-tap to show or hide the text. Revealed text is read aloud, so the app suggests headphones.

- With Increase Contrast, text gets bolder on pure black.

- "Show normally" displays messages in standard contrast when you need it, without the side protection.

- The lock is a static mask, so it works with Reduce Motion.

Try it first

The Demo tab shows a sample conversation in normal and private view, and lets you practise hold to read before your first real message.

Good to know

- Text in Sideproof: Private Messaging is harder to read from the side, not invisible. Someone right next to you in a dark room may still read it, and the app is no replacement for a privacy screen protector.

- Bright sunlight makes dim text hard to read for you too.

- It can't stop screenshots, cameras or someone looking straight at your screen.

- Anyone who receives a shared image can save it, brighten it or let text recognition read it.

- The iPhone keyboard can't be dimmed and shows each letter as you tap it.

- It works best on OLED displays. On LCD models such as iPhone 11 and iPhone SE, the effect is weaker.

No account and no tracking. The app collects no data, and your messages travel only through iMessage or the app you share them with.