Frequently Asked Questions¶

General¶

What is Mycel?¶

Mycel is a delay-tolerant mesh messenger for Android. It sends messages by hopping between nearby phones, without requiring internet connectivity.

Why "Mycel"?¶

Named after mycelium - the underground fungal network that connects trees in a forest. Like mycelium, Mycel connects devices in a resilient, decentralized network.

Is Mycel free?¶

Yes, Mycel is free and open source.

Can I use Mycel for emergencies?¶

No. Mycel is not suitable for emergency communications. Delivery can take hours or days with no guarantee of arrival. For emergencies, use official emergency services.

Is Mycel on the Play Store?¶

Not currently. Download from GitHub Releases.

Connectivity¶

Why didn't my message send immediately?¶

Mycel needs to find a nearby device to relay your message. If no Mycel users are around, the message waits until an encounter happens.

Can I use Mycel without internet?¶

Yes! That's the primary use case. Mycel uses Bluetooth and Wi-Fi Direct to communicate directly with nearby devices.

How far can messages travel?¶

With enough relay devices, messages can travel anywhere. Each hop typically covers ~100 meters. Messages ride along with people as they move.

Why does delivery take so long?¶

Messages travel through physical encounters between devices. More distance = more hops = more time. This is the trade-off for not requiring internet.

Permissions¶

Why does Mycel need location permission?¶

Android requires location permission to scan for Bluetooth devices. Mycel doesn't actually track or store your location - it only uses this permission for device discovery.

Why does Mycel need background permission?¶

To relay messages when you're not actively using the app. Without background permission, the mesh only works when the app is open.

Privacy & Security¶

Are my messages encrypted?¶

Yes, all messages are end-to-end encrypted. Only you and your recipient can read them.

Can relay devices read my messages?¶

No. Messages are encrypted before leaving your device. Relay devices can only see encrypted data and routing metadata.

Is there a server storing my messages?¶

No. Messages are stored only on devices - yours and the relay devices carrying them. No central server exists.

Do I need a phone number?¶

No. Mycel identifies you by a cryptographic key, not phone number or email.

Technical¶

What Android version do I need?¶

Android 8.0 or higher (API 26+). Full mesh features require Android 10+. Google Play Services is also required.

How much storage does Mycel use?¶

The app is ~50 MB. Message storage varies with usage.

Does Mycel drain my battery?¶

Mycel uses Bluetooth scanning which does consume some battery. Battery optimization settings can help balance connectivity vs. battery life.

What is the Nostr transport?¶

Nostr is an optional internet-based relay. When available, it can speed up delivery. Messages are still encrypted.

Troubleshooting¶

Messages stuck on "Pending"¶

Check that Bluetooth and Wi-Fi are enabled
Ensure location permission is granted
Make sure the app isn't being killed by battery optimization
Be patient - mesh delivery takes time

App keeps closing¶

Disable battery optimization for Mycel
Grant all requested permissions
Check that your device meets the requirements

Can't find nearby devices¶

Both devices need Mycel running
Check Bluetooth and Wi-Fi are on
Check location services are enabled
Try moving closer together

Updates¶

How do I update Mycel?¶

Download the latest APK from GitHub Releases and install over your existing version.

Can I get automatic updates?¶

Yes, use Obtainium to monitor for new releases.

Cannot add Mycel source from GitHub (Obtainium)¶

If you see a connection error while adding the Mycel source in Obtainium:

Check your internet connection
- Make sure your device has a stable internet connection
- Try switching between Wi-Fi and mobile data, then retry
Avoid restricted networks
- Some networks block or interfere with connections to GitHub
- If you're using a corporate, hotel, or public Wi-Fi network, try a different network
Disable VPN or network filtering temporarily
- VPNs, private DNS, or system-wide ad blockers may interrupt the connection
- Turn them off briefly and try again
Confirm the source URL
- Make sure the source URL is entered exactly as: https://github.com/ethene/mycel-releases
- Even small changes or missing characters can cause the connection to fail
Retry after a short wait
- Temporary network or service issues may resolve on their own
- Wait a few minutes and try again
Restart the app or device
- If the error persists, restarting Obtainium or the device can help clear temporary network issues
If the problem continues
- The issue is usually caused by network restrictions or connectivity problems
- Try again later or from a different internet connection
- You can also download the APK directly from GitHub Releases