SIGIL
A sentence, written as a circle.
Write a line of English. SIGIL draws it as a luminous circular mark you send through any messenger as an ordinary image, and the person on the other end reads your exact words back inside the app.
Someone sent you a circle. It reads back in English, on your own phone, inside this app and nowhere else.
Made on your iPhone. No account, no server, no network in the loop.
It looks like a language, not like junk
Most ciphers produce noise: a wall of base64 nobody wants in their chat. SIGIL produces a mark. Rings of glyph strokes around a fixed centre, drawn in cold light on black. Something a person will actually send, and something the person receiving it will ask about. That question is the whole point.
Every letter rewrites the whole thing
As you type, the entire circle re-forms on every keystroke. Nobody added that for flourish: changing one character changes every byte underneath, so every ring genuinely does change. You are watching the ciphertext move under your hands.
Open marks, and groups
An open mark is not private. Anyone with SIGIL can read it. That is how a mark travels, and it is the app's only advertisement. A group is a key you and one person, or you and several, exchange once, in person or over a channel you already trust. Marks written in a group read only for the people holding that key. Whoever holds the key can both read and write; a group is a shared room, not a one-way channel, so hand a key out the way you would hand out a spare key to a flat.
There is no decoder anywhere but the app
No web reader, no paste-in page, no API, no shortcut that hands back plaintext. If someone wants to read a mark, they install SIGIL. This is a deliberate constraint, not a missing feature.
Made on your iPhone
A renderer we wrote draws the mark, on your device. Encryption is Apple's own CryptoKit, and keys live in the iOS Keychain and nowhere else. There is no cloud model, no Private Cloud Compute and no server of ours anywhere in the loop. It works in Airplane Mode. Please check.
Private by construction
- No account, no login, no server, no sign-in. Nothing you write ever leaves the device.
- App Privacy label: Data Not Collected. The only network call is App Store purchases.
- Group keys are stored in the iOS Keychain. They are never transmitted by us, ever.
- The only way anything leaves your phone is the system share sheet, by your hand.
What SIGIL is not
SIGIL is not an occult or manifestation tool. It is not a messenger or a social network either: it has no inbox, no contacts and no transport of its own, and sending a mark means handing an image to an app you already have. It is not a secure-messaging product. What you write in a group is only as protected as the people you gave the key to, so do not use SIGIL for anything whose exposure would harm you.
What free includes
Free is complete in kind: full render quality, real groups, real sharing, and reading open marks with no limit. Free starts one group, and writing or reading inside any group whose key you hold never counts against the daily limit — joining a group somebody else started is unlimited at every tier. The 13-a-day limit applies to open marks on the free tier, and you keep two inks and your last 20 marks. Key backup and export are free at every tier, always: losing a phone must not cost you every group you are in. SIGIL Premium, which takes the group limit off, lifts the daily limit and adds inks, larger export and unlimited history, is available inside the app; the full terms are on the Terms page.
Questions
- What is the glowing circle someone sent me?
- A sigil. Someone wrote a line of English in SIGIL and the app drew it as a ring of light. The words ride in the rings, so the picture is the message. Open that image in SIGIL and you get the sentence they wrote.
- What app reads a circular symbol image?
- SIGIL, the app that drew it. Save the picture, install SIGIL on your iPhone, then import the image from Photos, Files or the share sheet. An open mark reads for anyone with SIGIL. A mark written in a group reads once you hold that group’s key.
- Can I decode a SIGIL glyph without the app?
- No. Reading happens inside SIGIL, on your own phone. There is no web reader and no paste-in page, and we will not add one.
- Does SIGIL need an account?
- No. There is no sign-up, no login, and no Sign in with Apple. Restoring a purchase needs no account either.
- How does the other person read it?
- They install SIGIL and import the image from Photos, Files, or the share sheet. If it is an open mark, it reads. If it is a group mark and they hold the key, it reads. If they do not hold the key, the app says so plainly and its words stay closed.
- Does it work offline?
- Yes, entirely. Only the App Store needs a connection. Turn on Airplane Mode and use the whole app.
- Is this a messenger?
- No. SIGIL has no inbox, no contacts, no directory and no transport of its own. It makes an image; you send that image with whatever you already use.
- How long can a phrase be?
- 145 characters, the same for everyone. The paid tier does not buy you a longer phrase.
- What if I lose my phone?
- Export your keys before that happens; it is free and always available. Without a key there is no recovery, by design. We hold nothing.
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