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In emergencies or disasters, there is often no internet available and in these cases classic messengers are useless. However, there are special messengers that also work without the internet and allow local communication between devices via Bluetooth or WLAN. This can also be helpful if the emergency numbers in the landline or mobile network fail.

Due to the system architecture and the differences between Android and iOS, it is very complex to develop comprehensive systems. Although an independent app/solution for both operating systems is highly desirable, it is not currently (Oct/2023) known. As many households use both Android and iOS devices, households that only use i-OS are at a disadvantage here.

Messenger apps for emergencies


Purpose: spontaneous network, emergency situation

  • also voice and video calls
  • Contacts can be added to each other in advance, e.g. via QR code
  • Android only; not for iOS

Advantage over Briar: simpler user interface

More information: >> here <<
Project page/source code: https://github.com/meshenger-app/meshenger-android (external)


Purpose: crisis areas, journalists, activists, emergency situations

  • Contacts can be added to each other in advance, e.g. via QR code
  • Mailbox function (for temporary storage of offline messages) possible when using a separate server
  • Android only; not for iOS

Advantage over Meshenger: contact also possible via internet connection, mailbox function possible

More information: >> here <<
Project page: https://briarproject.org (external)

Non-free messenger

For both smartphone OS (Android and iOS) there is e.g. “bridgefy” - however, this is not open source and is not recommended here due to provider dependency. If the company “turns off the tap”, is taken over or goes bankrupt, for example, it can quickly come to an end.

More apps for emergencies

WiFi Walkie Talkie

In addition to Meshenger and Briar, the app “WiFi Walkie Talkie” (also Android only; also available in F-Droid (external)) is another option. The app has the advantage that voice communication works without adding contacts beforehand - text messages are not possible here, however.

Source: F-Droid (external)

Trail Sense

Another very good support and option for calling for help in remote areas is the “Trail Sense” app, which is also open source and available via F-Droid (external).

The tools available here include a flashlight and whistle function! This can be used to send SOS signals, help or even individual signals. So an absolute recommendation for this case.

Source: F-Droid (external)

Further possibilities

No messenger apps, but still important …

Manual signaling

This can be done, for example, by knocking on pipes or brick walls.


SOS signal = three times short / three times long / three times short = dit dit dit / dah dah dah / dit dit dit (… — …)

Are there rules/guidelines on how often or at what intervals help should be sought/called for in emergencies? Please contact us for more information!