Offline Anki Sync: Linux ↔ Android (No Internet Needed)

Let’s say you have Anki on your Linux PC and AnkiDroid on your phone, no internet access, but you want to sync your cards wirelessly.

You can easily run a local Anki sync server on your machine, turn your PC into a Wi‑Fi hotspot, and connect your phone directly to it.

Step 1: Turn your Linux PC into a hotspot

Make sure your hotspot interface (e.g., ap0) is up and broadcasting. On Arch, I use create_ap or NetworkManager’s hotspot mode. Your PC gets an IP like 192.168.12.1 – that’s the server address.

Step 2: Start the correct sync server (temporary, for testing)

The built-in anki --syncserver is old and broken. Use the modern Python module instead:

SYNC_USER1=myusername:mypassword python -m anki.syncserver

You’ll see:

INFO listening addr=0.0.0.0:8080

To use a different port:

SYNC_PORT=9000 SYNC_USER1=myusername:mypassword python -m anki.syncserver

Leave this terminal open while you test. For a permanent background server, skip to Step 2b.

Step 2b: Run the server permanently in the background (systemd)

Instead of keeping a terminal open, create a systemd service so the server starts automatically on boot and restarts if it crashes.

Create a single directory for all Anki sync stuff (keeps your home folder clean):
```
mkdir -p ~/anki/data
```

Create a virtual environment and install anki inside that directory:

python3 -m venv ~/anki/venv
source ~/anki/venv/bin/activate
pip install anki
deactivate

Create the systemd service file:

sudo nano /etc/systemd/system/anki-sync-server.service

Paste this (replace myusername and mypassword with your credentials):

[Unit]
Description=Anki Sync Server
After=network.target
 
[Service]
Type=simple
User=myusername
Group=myusername
WorkingDirectory=/home/myusername/anki
 
Environment="SYNC_USER1=myusername:mypassword"
Environment="SYNC_BASE=/home/myusername/anki/data"
Environment="SYNC_HOST=0.0.0.0"
Environment="SYNC_PORT=8080"
 
ExecStart=/home/myusername/anki/venv/bin/python -m anki.syncserver
 
Restart=on-failure
RestartSec=10
 
[Install]
WantedBy=multi-user.target

Enable and start the service:

sudo systemctl daemon-reload
sudo systemctl enable --now anki-sync-server.service

Check that it’s running:
```
sudo systemctl status anki-sync-server.service
```
You should see active (running). The server now runs in the background forever – no terminal needed.

Step 3: Configure Anki desktop (on the same PC)

Open Anki → Tools → Preferences → Syncing
Enable “Self-Hosted Sync Server”
Set URL: http://127.0.0.1:8080/
Now sync – when asked for “AnkiWeb ID”, enter the same username/password you used in SYNC_USER1.

Step 4: Configure AnkiDroid (on your phone)

Connect your phone to your PC’s hotspot.
In AnkiDroid: Settings → Advanced → Custom sync server
Enable “Use custom sync server”
Sync URL: http://192.168.12.1:8080/ (use your PC’s hotspot IP)
Media sync URL: http://192.168.12.1:8080/msync/
Username = your chosen username (e.g., myusername)
Password = your chosen password

⚠️ Critical Android setting

Google blocks unencrypted HTTP by default. You must allow it for AnkiDroid:

Go to Android Settings → Apps → AnkiDroid → Allow cleartext traffic → Yes

Step 5: Sync

Tap the sync button in AnkiDroid. If you’re using the systemd service, you won’t see live logs – but you can watch them with:

journalctl -u anki-sync-server.service -f

You’ll see 200 OK responses – that’s success.

“Email or password incorrect”?

That error just means you entered credentials in the wrong place. Put your local username/password into AnkiDroid’s Email address and Password fields – ignore the “AnkiWeb” label.

Mücteba

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