betanin uses apprise for notifications. so anything supported there will work. but some include

• email
• discord
• telegram
• emby

pip install --user betanin

# start server
betanin
# a config file will be created, add your credentials to it
# start again
betanin [--host=<host>] [--port=<port>]
# ui will be available at port
# you may also use env vars instead, eg
BETANIN_HOST=0.0.0.0 betanin
BETANIN_PORT=4030 betanin

# optionally start cli (for db operations, debugging)
betanin-shell
# or if docker
docker exec -it <container_id> betanin-shell

docker pull sentriz/betanin

/b/.config/betanin/ for a persistent betanin config
/b/.config/beets/ for a persistent beets home (point this to your current beets home if you have one)
/music/ so beets can access your music
/downloads/ so beets can access your downloads

betanin:
  image: sentriz/betanin
  ports:
    - 9393:9393
  restart: unless-stopped
  environment:
    - UID=1000 # (optionally) set user id
    - GID=1000 # (optionally) set group id
  volumes:
    - ${DATA}/betanin/data:/b/.local/share/betanin/
    - ${DATA}/betanin/config:/b/.config/betanin/
    - ${DATA}/betanin/beets:/b/.config/beets/
    - ${MEDIA}/music:/music/
    - ${MEDIA}/downloads:/downloads/

create a script named done.sh or anything you like, and make it executable:
chmod +x done.sh

...
"script-torrent-done-enabled": true,
"script-torrent-done-filename": "/scripts/done.sh",
...

#!/bin/sh

curl \
    --request POST \
    --data-urlencode "path=<path_to_transmission_downloads>" \
    --data-urlencode "name=$TR_TORRENT_NAME" \
    --header "X-API-Key: <your_api_key>" \
    "https://betanin.example.com/api/torrents"

volumes:
  - ${DATA}/transmission/config:/config
  - ${DATA}/transmission/scripts:/scripts
  - ${MEDIA}/download:/downloads

create a script named done.sh or anything you like, and make it executable:
chmod +x done.sh
you must also be using the Execute plugin, set to the Torrent Complete event

#!/bin/sh

curl \
    --request POST \
    --data-urlencode "path=<path_to_deluge_downloads>" \
    --data-urlencode "name=$2" \
    --header "X-API-Key: <your_api_key>" \
    "https://betanin.example.com/api/torrents"

create a script named done.sh or anything you like, and make it executable:
chmod +x done.sh

open qbittorrent Tools > Options > check Run external program on torrent completion

set the path to the above done.sh and arguments such as

/path/to/done.sh "%L" "%R"

#!/bin/sh

echo "category: $1"
echo "path: $2"

[ "$1" != "music" ] && exit

curl \
    --request POST \
    --data-urlencode "both=$2" \
    --header "X-API-Key: <your_api_key>" \
    "https://betanin.example.com/api/torrents"

now any music downloaded to the music category will be imported by betanin

there is not much else to do, write your code, python -m betanin.entry.betanin, kill it, write your code, etc. the webserver will be available at http://localhost:9393/. the static frontend is served at /, and the api is served at /api. (there is a swagger ui there too) also see python -m betanin.entry.shell.
if you need to do a manual migration do env FLASK_APP='betanin.application:create' flask db migrate --directory betanin_migrations/ (then upgrades are automatically done on betanin start)

start the backend with python -m betanin.entry.betanin, but don’t use the static frontend served at http://localhost:9393/. Instead, in a new shell, do npm --prefix betanin_client/ run serve and use the frontend served at http://localhost:8081/. it will look for a backend listening on port 9393 locally. after that you can edit anything in betanin_client/src, it will be linted and automatically reflected in your web browser.