Home Assistant is the most flexible target for the MathNet webhook. Once a redemption is plumbed through, you can hook any HA automation to it — lights, media players, TTS, locks, smart plugs, Google Home/Alexa speakers, the works.

This guide assumes you already have a Home Assistant instance accessible from your local network (or via Nabu Casa Cloud / your own reverse proxy if you want to use MathNet from outside your house).

1. Create the webhook trigger in Home Assistant

In HA, go to Settings → Automations & Scenes → Create Automation → Start with an empty automation.

Pick Webhook as the trigger. HA will generate a long random webhook ID — keep it. The full URL you give to MathNet will look like:

https://your-ha-instance/api/webhook/mathnet_redeem_<random>

(Or http://homeassistant.local:8123/api/webhook/... for purely-local installs.)

Save the automation. It won’t do anything yet — we still have to give it an action.

2. Paste the URL into MathNet

In MathNet → Settings:

  1. Toggle Enable reward system on
  2. Paste the HA webhook URL into Webhook URL
  3. Set Points per credit to whatever feels right
  4. Tap Save Settings
  5. Tap Test webhook to confirm reachability — you should see ✅

3. Wire up the action

Now pick what should happen when a credit is redeemed. Three examples below — combine and modify as you like.

Example A: Flash the play-room lights

trigger:
  - platform: webhook
    webhook_id: mathnet_redeem_<random>
    allowed_methods: [POST]
    local_only: false

action:
  - service: light.turn_on
    target:
      entity_id: light.playroom
    data:
      brightness_pct: 100
      rgb_color: [255, 215, 0]
      flash: long
  - delay: "00:00:03"
  - service: light.turn_off
    target:
      entity_id: light.playroom

Example B: Speak an announcement on a Google/Alexa speaker

trigger:
  - platform: webhook
    webhook_id: mathnet_redeem_<random>
    allowed_methods: [POST]
    local_only: false

action:
  - service: tts.google_translate_say
    data:
      entity_id: media_player.kitchen_speaker
      message: >
        Great job! You earned a credit. Your balance is now
        {{ trigger.json.balance_after }} credit{{ 's' if trigger.json.balance_after != 1 else '' }}.

The trigger.json.balance_after template grabs the post-redemption balance from MathNet’s payload (see the payload spec).

Example C: Unlock 30 minutes of TV time

Assuming you have a smart plug controlling the TV and a timer.tv_allowance helper:

trigger:
  - platform: webhook
    webhook_id: mathnet_redeem_<random>
    allowed_methods: [POST]
    local_only: false

action:
  - service: switch.turn_on
    target:
      entity_id: switch.tv_smart_plug
  - service: timer.start
    target:
      entity_id: timer.tv_allowance
    data:
      duration: "00:30:00"
  - service: notify.parents
    data:
      title: MathNet credit redeemed
      message: TV powered on for 30 min ({{ trigger.json.balance_after }} credits left)

Pair this with a separate automation listening to timer.finished that turns the smart plug off again.

Home Assistant webhooks are unauthenticated by default. If your HA instance is exposed to the internet, you’ll want one of these protections:

Option 1: Local-only webhook. Set local_only: true in the trigger config, then use a VPN (Tailscale, WireGuard) on the iPad/iPhone so MathNet’s request originates from inside your network. This is the most secure approach and works flawlessly with Tailscale.

Option 2: MathNet admin password. In MathNet Settings, set an Admin password. MathNet sends it as Authorization: Bearer <password> on every redeem. Use an HA template condition to verify:

condition:
  - condition: template
    value_template: >
      {{ trigger.headers['authorization'] == 'Bearer your-shared-secret' }}

Option 3: Obscure path. HA webhook IDs are already long and random. Don’t paste yours into screenshots, public forums, or third-party services. Treat the URL like a secret.

I recommend Option 1 (Tailscale) if you’re already using Tailscale on the students’ devices. Otherwise the Admin password header is fine for a typical home setup.

5. Test it end to end

In MathNet’s Bank view, do an Exchange (if you have points to convert) and then Redeem. The HA automation should fire within a second or two. If nothing happens, check:

  • HA’s Automations → Logbook for whether the trigger fired
  • HA’s logs (Settings → System → Logs) for any errors
  • MathNet’s transaction history — failed redemptions are logged with the response code

Going further

A few automations the MathNet community has built:

  • Streak bonus — if trigger.json.balance_after crosses a threshold (e.g. 10 credits in a day), trigger a bigger reward
  • End-of-week summary — log each redeem to InfluxDB or a Google Sheet via HA’s rest_command, display weekly charts on a dashboard
  • Family dashboard — track per-device credits with trigger.json.device_name and show each student’s progress on a wall-mounted tablet

Home Assistant is genuinely the killer app for the MathNet webhook. Once it’s plumbed through, you can iterate on the reward side without ever touching the math side.