Messenger Without Internet — No Wi-Fi, No Data, No SIM
OSHI is a free, open-source, end-to-end encrypted messenger for iOS and Android that uses Bluetooth and Wi-Fi mesh networking to send messages without Internet or cellular service. OSHI does not require a phone number, email address, or account.
"Messenger without Internet" usually means one of three things: you have no data plan or SIM, the network around you is saturated or shut down, or you are somewhere with no coverage at all. OSHI handles all three the same way, by moving messages directly between phones. Here is what that means in practice.
No SIM, no data plan
OSHI never asks for a phone number, so a phone with no SIM card can use it fully. Identity is a keypair generated on the device; you add someone by scanning their QR code or pasting their public key. Nearby, messages go over Bluetooth and Wi-Fi Direct with no data used. Farther away, OSHI uses whatever Internet the phone has — a café Wi-Fi is enough, and no SMS verification ever arrives because none is needed. This is also why OSHI works for children's devices, spare phones, tablets and iPods that never had a number.
Network shut down or jammed
At a stadium, festival or protest the towers may be up but useless, or switched off. OSHI's mesh does not care: with the app open, phones find each other over Bluetooth Low Energy at roughly 100 m in the open, and each phone will relay for the others, up to five hops, storing and forwarding when the next phone is not yet in range. Every packet is encrypted end to end before it leaves your phone, so a relay learns nothing but that it carried some bytes. See the Internet shutdown survival guide for the wider toolkit.
No coverage at all
On a trail, a boat, a plane or in a basement, the mesh is the only path there is. Two OSHI phones in the same cabin can chat, share photos and swap live location. A hiking group strung along a path can pass messages down the line as long as each pair is within Bluetooth range. Offline maps with routing are built in, so you can also navigate without a signal. What OSHI cannot do is reach someone hundreds of kilometres away with no Internet anywhere in between; no phone app can. For kilometre-scale links, OSHI's optional LoRa node or a Meshtastic radio is the right tool.
OSHI mesh in numbers
- Range per hop: roughly 100 m in the open, 10–30 m through walls (Bluetooth Low Energy).
- Hops: up to 5 phones can relay a message, store-and-forward, so a dense group can carry it 500 m or more.
- What travels over the mesh: text, photos, voice notes and small files (larger payloads move over Wi-Fi Direct).
- What relays see: only ciphertext. Every hop is end-to-end encrypted (X3DH + Double Ratchet, AES-256-GCM).
- Requirement: the other phones must be running OSHI with the app open; there is no infrastructure at all.
- When Internet returns: OSHI syncs automatically over the Internet, Tor or a covert channel.
Exactly what needs a connection
| Action | Works with no Internet? |
|---|---|
| Text a nearby OSHI user | Yes — Bluetooth LE, relayed up to 5 hops |
| Send a photo, voice note or file nearby | Yes — Wi-Fi Direct between phones |
| Group chat with nearby members | Yes |
| Add a contact | Yes — scan their QR code in person |
| Offline maps and routing | Yes — if the region was downloaded beforehand |
| On-device AI assistant | Yes — runs locally |
| Message someone far away | No — waits until a phone in the mesh gets Internet |
| Voice or video call | No — needs an IP path; encrypted end to end when it has one |
| Download new map regions or AI models | No — do this before you leave |
Setting it up so it works on the day
- Install OSHI on iOS (App Store) or Android (APK from this site) on every phone in your group.
- Add each other by QR code while you are together. This needs no server and no signal.
- Download the map region you will be in.
- Test once: put every phone in airplane mode, open OSHI, send a message. Watch it arrive.
- On the day, keep OSHI open (or at least in the foreground periodically) on the phones that should relay. iOS in particular limits background Bluetooth.
Other apps that message without Internet
OSHI is an alternative to Bridgefy, Briar, Meshtastic and bitchat for offline communication, and to Signal for private messaging. Bridgefy is popular but closed source and, by its own instructions, needs Internet the first time you open it. Briar is audited and open but Android-only. bitchat is public-domain Bluetooth-only chat. Meshtastic needs a LoRa radio per person. Our best offline messenger comparison puts them side by side with sources.
Frequently asked questions
Can I use OSHI without a SIM card?
Yes. OSHI has no phone-number registration, so a phone with no SIM can install it, add contacts by QR code, and message nearby users over Bluetooth and Wi-Fi Direct. With any Wi-Fi it can also reach distant contacts.
Does OSHI use my mobile data?
Not for nearby messages: those travel phone-to-phone over Bluetooth and Wi-Fi Direct. When a contact is out of mesh range and your phone has a connection, OSHI uses it to deliver the message.
Can I message someone in another country without Internet?
No app can. OSHI can carry a message a few hundred metres over the mesh, then deliver it as soon as any phone in the chain has Internet.
Do both phones need OSHI open?
Yes, for discovery over Bluetooth. OSHI's App Store listing states that both phones need the app open to find each other, roughly 100 m apart in the open and much less through walls.
Keep exploring
Offline messengerMesh messengerInternet shutdown survival guideBest offline messenger apps comparedHow OSHI mesh worksOSHI FAQTry OSHI free
Encrypted messaging with no phone number, offline Bluetooth and Wi-Fi mesh, offline maps and on-device AI.