early access · source not yet published
Watch the text behind this sentence turn into ciphertext on its own — then move your cursor across it and drive the wavefront yourself. Kalvien generates your keys on your device and never sees them, so we can deliver your words and never open them.
The actual app
This isn't a screenshot or a video — the composer works. Type something and watch it get sealed on this device before it moves: the byte count under your bubble is a real ciphertext length and those first three bytes are really yours. It is a demonstration, not the shipped client — the app is Android and encrypts with libsodium; your browser only offers its own cipher suite. Same guarantee, different primitive, and we say which is which further down.
In the app today
crypto_box — X25519 key agreement, XSalsa20-Poly1305 cipher. Your private key is generated on the device and stored in Keystore-backed storage.Also in the build: pinned, muted and archived chats · block and report · read receipts off by default · passcode, biometric and decoy lock · voice/video calls · voice notes · linked devices · safety-number QR verification · encrypted backup · stories and channels · push notifications · light and dark themes · delete your account and everything in it, from inside the app.
Six screens, all of them real
One thread can't show you group key handling, your privacy defaults, or the way out. Every screen here is backed by something that runs — where a screen shows a limit rather than a feature, it says so on the screen. Swipe, or use the arrows.
Pinned
All
Encryption
4 members
When someone joins or leaves, the key rotates to a new epoch and is resealed. We store four envelopes and hold no key that opens any of them.
This removes your account, your messages, your keys, your contacts and your settings. It cannot be undone.
No retention window, no "deactivated" state, no email asking you to reconsider. Two taps from Settings.
Other ways
We never read your address book — there is no contacts permission in the app. Exact-number lookup returns an account only when that person chose everyone, or chose contacts and already saved you.
Your theme is stored on the device. It never becomes account data, because there is no profile for it to sit in.
Defaults matter more than settings: read receipts begin off, and Android screenshot/screen-recording protection is enabled. App lock can use a passcode, strong biometric, or an isolated decoy profile.
Scroll to send · the network is watching
your phone
their phone
The interceptor sees an opaque blob. It knows a message happened. It cannot tell you what it said.
Real cryptography · running in this tab
Each tile below is one real byte of ciphertext, produced right now by your own browser. Change a single character and watch how many of them flip — that avalanche is the property that matters, and it's the same one the app relies on. The algorithms differ: this runs on what browsers ship, and the Android app uses libsodium's X25519 and XSalsa20-Poly1305. Saying "the exact construction the app uses" would be easier and untrue.
—
Fresh nonce every keystroke · nothing here touches the network
· the app does the same job with crypto_box
Don't take our word for it
We haven't published the source yet, so a promise is all we'd otherwise have. Instead: here is the request that leaves your device, the row it becomes on our server, and what happens when someone tries to open it. All three are generated live from the box above — edit it and watch them change.
encrypting…
Nothing on this page talks to a server — the keys, the ciphertext and the failed decrypt all happen in this tab, which you can confirm in the same network panel. When the source is published this section becomes redundant, and that will be a good day.
The differences that matter
These are backed by the Android client and service today. Phone-number discovery is off by default and enforced by the service, not just the UI. Channels are public broadcast content, while private conversations are end-to-end encrypted.
01
in the appPhotos and video are encrypted on your phone with a one-off key, and that key is sealed to the recipient. What lands in our storage bucket is a file we cannot open — verified by a live end-to-end test, not by assertion.
02
in the appSet a timer and a sweeper on the server deletes the row every sixty seconds — not a client-side trick that hides the message while the bytes quietly persist. The copy on your phone and the copy on ours both stop existing.
03
in the appSigning up needs a number and an SMS code — we're not going to pretend otherwise. What's different is afterwards: no other user is ever shown it. It isn't in your profile or in the API response your contacts get, people reach you at an @username, and exact-number discovery is off by default.
04
in the appPrivate reactions are hidden encrypted conversation events. The service routes ciphertext and never stores the emoji in a readable reaction column. Channel reactions remain readable because channels are public.
05
in the appEach device renders the real identity-key fingerprint and QR payload. Compare or scan them in person to detect a substituted public key.
06
in the appExact-number discovery is off by default. You can allow everyone, contacts you have already saved, or nobody; the backend enforces that choice and never returns the number itself.
07
in the appOne-time prekeys protect one-to-one messages and upgraded conversations refuse a legacy downgrade. Compromise of a current identity key does not expose earlier forward-secret ciphertext.
08
in the appA second passcode opens an isolated harmless profile, while the real profile remains separately encrypted. Strong-biometric unlock is disabled while a decoy is armed so it cannot reveal which profile is real.
09
in the appBlur-until-tapped sealed messages, encrypted edits, and encrypted voice notes all travel through the private conversation envelope. Microphone access begins only when you record or call.
10
in the appGroup keys are wrapped separately to each authorised member and rotate after membership changes. Broadcast channels are implemented as a deliberately readable public surface, not disguised as private chat.
11
in the appOne-to-one voice and video calls use authenticated signalling and WebRTC DTLS-SRTP. Media goes peer-to-peer when possible and uses a TURN relay when needed; Kalvien does not record it.
12
in the appAuthorise another Android device with an expiring pairing offer, transfer private material to that authorised session, review every active device, and revoke one without server-side key escrow.
Disappearing messages
An hour, a day, a week. A sweeper on the server deletes the ciphertext at rest every sixty seconds — not a client-side trick that hides the row while the bytes quietly persist.
deleted · both devices · and the disk
Fit, not funnel
A privacy tool that claims to be for everyone is either lying or dangerous. Kalvien is for everyday privacy, not operational security — and the second list matters more than the first.
The gap between "nobody's business" and "my life depends on it".
These aren't edge cases. If you're in this column, we'd rather lose you than have you rely on us.
The part everyone else omits
Every messenger lists what it protects. Almost none list what it doesn't. Here is where Kalvien is weak today, written down before you ask — a privacy tool that oversells itself is worse than one that's honest about its edges.
Forward-secret encryption protects private content, not who communicated, when, delivery/read state, attachment size, or call-routing information. The service still processes those facts.
Message content is sealed. The metadata around it — sender, recipient, timestamp — is not. We can't read your words. We can see the shape of your conversations.
Safety-number QR comparison is available, but it only detects a substituted key when you actually compare the code with your contact through a trusted channel.
Linked Android devices and encrypted local backups exist. Kalvien cannot open or reset them, so losing every authorised device and your backup still means losing the history.
No independent party has reviewed our cryptography or our server. We use vetted primitives through libsodium rather than rolling our own, which is the floor, not a substitute. Until someone outside this team has looked, treat every claim on this page as ours rather than verified.
Channel posts, media, comments, reactions, and moderation data are readable broadcast content. Do not mistake a channel for an end-to-end encrypted private conversation.
WebRTC encrypts live audio/video and Kalvien does not record it. The service and any TURN relay still process participant IP addresses, timing, status, and traffic volume.
A number verified by Firebase Authentication is required. We hold that number, hide it from other users, and let people talk at an @username. Exact-number discovery is off by default and enforced by the backend.
Threat model
Encryption isn't a yes or no. It's a list of adversaries and what each one walks away with — so here's ours, including the four rows where the answer is partly or out of scope. The boundary below is checked against the current client and service, not a feature promise.
A café network, a hotel, an ISP, anyone tapping the wire. They see that a message moved and nothing about what it said. Scroll back to the interceptor — that's this row, animated.
A dump of our storage is a table of ciphertext and a bucket of encrypted files. There is no body column, no preview field, no search index — we verify this with a live test that encrypts, stores, and then fails to read it back. What a thief does get is the metadata row: who, whom, when.
We hold ciphertext we can't open — and sender, recipient and timestamp that we can. We can't read your words. We can see the shape of who you talk to.
Content we genuinely cannot produce; metadata we can, because we have it. That is the whole honest answer. We do not publish a warrant canary — we'd rather say nothing than sign a document we have no process to keep true.
Safety-number QR comparison lets two people compare the identity keys their devices received. The protection depends on actually performing that comparison over a trusted channel.
Passcode/strong-biometric app lock, an isolated decoy profile, and Android screenshot/screen-recording protection reduce exposure. They do not stop another camera, a compromised OS, or someone who already has the real unlock secret.
One-time prekeys protect one-to-one ciphertext sent on the forward-secret path and upgraded conversations refuse downgrade. A compromised live device can still expose content already decrypted on that device.
Someone with the budget to attack your phone directly, or to compel us and gag us about it. We are not the tool for that, and no messenger should tell you it is on its own.
Notice what isn't on this list: "unbreakable", "military-grade", "NSA-proof". If your adversary is in one of the bottom rows, read who this is for again — we'd rather you used Signal than trusted us with something we can't carry.
Evidence, including the limits
A feature list is not proof. This snapshot separates implementation, local live evidence, and production boundaries so a green unit test is never presented as a deployed result.
| Claim | Implemented boundary | Evidence run | Still external |
|---|---|---|---|
| Private content is unreadable by the serviceChannels, profiles, reports, routing and call metadata are excluded from this claim. | Chats, private media, stories, reactions and rich actions | Two-account ciphertext-only database check | Repeat after production deploy |
| Voice and video calls are realOne-to-one Android calls; no group-call or cross-platform claim. | Signed signalling, WebRTC DTLS-SRTP and TURN | Normal voice/video plus relay-only two-device calls | Managed TURN production credential and repeat |
| Phone discovery respects your settingMissing or malformed settings fail closed. | Nobody by default; contacts or everyone only by choice | Server policy tests and exact-match route | Repeat against deployed revision |
| Linked devices do not share plaintext with the serverAuthorised Android installations only. | Encrypted pairing bundle, device keys, history and revocation | Policy/JVM/instrumentation and local device flow | Production multi-device repeat |
| The release bundle is installable and constrainedNo contacts, SMS, call-log, location or broad media permission. | Four complete ABIs, no cleartext, backup disabled | 154 JVM, 111 device, 105 server, lint, bundletool and signature | Play Console review and rollout |
| Assurance limits are publicSource publication and independent review matter for a security product. | Source not published; no independent audit | Internal tests and local live validation only | Independent security and legal review |
Verified 10 August 2026 against the current repository and local device evidence. If code or deployment state changes, this snapshot must be refreshed before public deploy. If a row is wrong, tell us and we'll correct it here rather than quietly leave it.
Current boundaries
The messaging, calling, device, privacy, story, channel, and encrypted backup flows described above are implemented. These are the remaining assurance and platform facts, not deferred Android feature promises.
The Android client, backend, signalling, and cryptographic integration have not been assessed by an independent security firm.
Kalvien does not currently offer iOS, desktop, or web clients. Linked-device support links authorised Android installations.
The implementation cannot yet be inspected by the public. Treat that as a real limit when deciding whether to trust it.
Channels, profiles, reports, and routing metadata are not end-to-end encrypted. Private chats, private media, stories, reactions, and rich actions are.
Before you ask
Early access is free. We haven't decided how Kalvien pays for itself long term, and we'd rather say that than invent a pricing page. What we can commit to: there is no ad system in the codebase, and adding one would mean reading metadata we currently don't touch.
Link another authorised Android device and create an encrypted local backup before you need either. Kalvien cannot decrypt or reset that backup; if you lose every authorised device and the backup, the history is permanently unreadable.
Not in private conversations. Messages, media, stories, reactions, and rich actions are encrypted on your device before they reach us. We can see routing metadata, and we can read channel content, profiles, and reports; those boundaries are listed in what we don't claim.
Authenticated X25519/XSalsa20-Poly1305 encryption, one-time prekeys for forward-secret one-to-one messages, wrapped symmetric keys for groups/stories/media, and WebRTC DTLS-SRTP for calls. We use vetted primitives rather than writing them ourselves. The browser demo uses the browser's cipher suite and demonstrates the property, not the Android implementation.
No, and we won't pretend otherwise. Kalvien implements forward-secret one-to-one messages and safety-number verification, but Signal's clients and protocol are mature, published, and repeatedly scrutinised; Kalvien has not had an independent security audit. If your safety depends on the answer, use Signal.
Not published yet. For a tool that asks you to trust its cryptography, that's a fair thing to hold against us — verifiable claims beat stated ones. It's the reason the page shows you real ciphertext rather than just describing it.
Android, in early access. There is no iOS, web, or desktop client — if you've read something on this page that sounds like a browser app, that's the demo above, which exists to show you ciphertext rather than to be the product.
Store it, confirm it, and email you once when we launch. Nothing else — no drip sequence, no sharing, no analytics profile. Details in the privacy notice.
Before you join the list
No dark patterns and no surprise permission prompts — so here is every screen, in order, including the two that exist only because we ask for a phone number.
01
Your number A country and a number. This is the step we'd remove if we could — it's how we stop one person minting a thousand accounts.02
The six digits The second and last sign-in step that involves your number. It is hidden from other users, and exact-number discovery stays off unless you change its visibility.03
A handle and a vibe Your @username is how people reach you, plus an optional note — 60 characters, gone in a day.04
Keys, made here Generated on the phone, held in Keystore-backed storage, not exportable. We receive the public half and nothing else — which is also why nobody, us included, can recover your messages later.about 40 seconds
Never asked for: your device contacts, your location, SMS contents, call log, broad photo library, or a credit card. Camera and microphone are requested only for QR/video/voice flows you start. Create an encrypted backup or link another device if you need continuity.
One email, when there's something real to open. No drip campaign, no newsletter, no "we've updated our privacy policy".