Your energy. Your server. Your data.

wattlensi keeps your whatwatt Go data at home, on your own server. Live, cloud-free, at full resolution, for as long as you want.

Something in your home is costing you money right now.

Your smart meter never stops reporting on your household. wattlensi stores that data on your own hardware and turns it into answers: What’s running right now? What did this month cost? And why was Sunday so expensive?

See it as it happens

The display keeps pace with your meter, typically updating every five seconds.

Keep everything

Every reading is kept at full resolution, even years later.

Spot the changes

Compare days, months and years to see what’s different.

Stay independent

Your data lives on your server and stays there.

Everything your meter knows, in plain view.

From current power draw to year-on-year comparisons, wattlensi shows your energy use on phone and desktop, in kWh or CHF.

Live

Right now, as fast as your meter reports.

Every new reading appears instantly, with no reload. See what your home is drawing at this moment and what it’s costing you.

Chart of the last 2 minutes, 15 minutes, 1 hour or 24 hours
Hourly cost based on your tariff
Current per phase, with imbalances flagged

Day

Your day, in 15-minute steps.

Base load, peaks and daily total at a glance, compared with the same weekday over the past eight weeks. Plus your three biggest 15-minute periods.

Tap for the value of any 15-minute period
Estimates are shown lighter, so nothing is hidden
Daily cost, calculated from your tariff

History

From a single hour to a full year.

In kWh or CHF, at full resolution, with no expiry date.

Browse by day, week, month or year
Key figures including cost, base load and highest-use weekday

Year

365 days on one page.

The heatmap shows every day of the year, from low (blue) to high (orange). The forecast estimates how the current month will end, in kWh and CHF.

Forecast based on your weekday pattern over the past eight weeks
Tap a day to open its month
Monthly bars alongside the previous year

Compare

What changed?

Put weeks, months and years side by side. Periods still in progress are compared fairly, always up to the same day and time.

Against the previous period and the previous year
Last 12 months against the 12 before
Weekday profile pinpoints which days changed
New comparisons unlock as your data grows

Costs

Your tariff, your bill.

Enter energy, grid, levies and fixed fees just as they appear on your electricity bill, each with its own VAT. wattlensi prices every 15 minutes at the rate that applied at the time.

Single or dual tariff, with your own peak and off-peak hours
Tariff periods, so new prices never alter past bills
A reminder in December if next year’s tariff is missing

Reports

Monthly and yearly PDF reports.

Covering consumption, costs, comparisons, calendar and bill.

Delivered by email or Telegram on the 1st of each month at 07:00, if you wish
Monthly and yearly, in German or English
Completed periods are archived

Alerts

wattlensi tells you when something’s off.

By email, Telegram or both. You set the limits and the quiet hours when nothing gets sent. One message per event, at most.

Power peak above your limit
Night-time base load too high
Daily consumption limit exceeded
whatwatt Go offline after an outage
Next year’s tariff missing or CSV import failed

Water

Your water meter, too.

If a water meter is linked to your smart meter, wattlensi shows the reading, daily use and monthly total, exactly as the device reports them.

Every feature at a glance.

Analysis

Real-time consumption at your meter’s pace, with charts of up to 24 hours
Current per phase, with imbalances flagged
Daily profile with base load and peaks
History from hours to years, in kWh or CHF
Compare weeks, months and years
Year heatmap with monthly forecast
Water meter, if your smart meter reports it

Costs

Tariffs that mirror your electricity bill, with VAT per line item
Single or dual tariff
Costs per hour, day, month and year
Completed periods stay unchanged
Reminder when next year’s tariff is missing

Reports

Monthly and yearly PDF reports, in German or English
Includes costs and comparisons
Emailed on the 1st of each month at 07:00
Or sent as a PDF to your Telegram channel

Alerts

Push notifications to your Telegram channel
Email via your own mail server or any other provider
Custom limits for power peaks, base load and daily consumption
Alert when the meter stops sending data
Alert when an import fails
Choose your own quiet hours and language
Each event is reported only once

Household and security

Web app: installs on your phone without an app store, light or dark, German or English
For the whole household: invite others by email, as administrators or read-only users
Passkeys with Face ID, fingerprint or security key
Two-factor authentication with an authenticator app
See signed-in devices and sign them out

Homelab and operations

Import existing data: monthly CSV files from the whatwatt cloud or SD card, with a preview and validation first
Automatic fallback: if MQTT fails, wattlensi switches to REST on its own and back again afterwards
Diagnostics: every meter value with its OBIS code, plus reading interval, gaps and 30-day coverage
API: documented REST API with read and write tokens, live WebSocket and Prometheus metrics
Fast: the API returns a full year of data in under 25 ms, measured in an LXC with 2 GB of RAM
Guided whatwatt Go setup
Debian packages for amd64 and arm64

Up and running in four steps.

Get a whatwatt Go

Order a whatwatt Go online and connect it to your smart meter. Check first that your meter is compatible.

Install wattlensi

A single command will set up wattlensi on a fresh Debian 13 or Ubuntu 24.04/26.04 system, in an LXC container or a VM.

Connect

Enter your whatwatt Go’s address in the setup assistant. It checks the device and sets up the data connection.

Get started

Enter your tariff, import older data if you have it, and watch your electricity flow.

$ [INSTALL COMMAND, COMING WITH THE RELEASE]

We recommend 2 GB of RAM. wattlensi requires a whatwatt Go and a Linux server on your network.

FAQ

What is wattlensi?

wattlensi is free, open-source energy monitoring software for the whatwatt Go. It runs self-hosted on your own Linux server, keeps every reading at full resolution with no cloud, and shows live electricity use, costs in CHF, PDF reports and alerts.

Is wattlensi available yet?

Not yet. wattlensi is in development, and the install command will come with the release.

What do I need to run wattlensi?

A whatwatt Go on a compatible smart meter, and a Linux server on your network running Debian 13 or Ubuntu 24.04/26.04, in an LXC container or a VM.

How much does wattlensi cost?

wattlensi is free and open source. All you need is your own server and a whatwatt Go.

Is the whatwatt Go compatible with my smart meter?

Check with your grid operator or on the whatwatt website that your smart meter is compatible and its data port is enabled. If you’re with Regionalwerke Baden, it works out of the box.

Does wattlensi work with other devices?

No. wattlensi is built exclusively for the whatwatt Go, which is exactly why the two work so well together.

Which whatwatt licence do I need?

With PLUS or PRO, wattlensi uses MQTT, with REST as a fallback. With FREE, it uses the device’s live data stream. Setup detects your licence automatically.

Can I import my old data?

Yes, if you have monthly CSV files from the whatwatt cloud. Otherwise, wattlensi starts collecting from the day you install it.

How much storage does the data take up?

Not much. A year of readings at full meter resolution takes up about 80 MB (measured with simulated data).

Can I use wattlensi away from home?

That’s up to you. By default it stays on your home network. To reach it from outside, you can use a VPN, for example.

Is wattlensi an official whatwatt product?

No. wattlensi is an independent community project and isn’t affiliated with whatwatt.