TRMNL BWRY: An E-Ink Display Against Expired Yogurt

There is this moment that probably everyone knows.

You clean out the fridge, and in the back left corner sits a yogurt that expired eleven days ago. Bought with good intentions. Forgotten with a system.

For a long time I blamed my character.

By now I believe: it is a data problem.

The expiry date lives in the worst database in the world

The information exists.

Every package has a best-before date. Printed tiny, preferably on a fold, preferably facing away from the door, behind the milk, at five degrees.

To know what needs eating this week, I would have to open the fridge and rotate every single package. Nobody does that, obviously.

One quick word in defense of the date: I am fully aware that a best-before date is not an expiry date. It says best before, not deadly after. Yogurt does not turn at midnight, and hard cheese and mustard are still laughing about it weeks later.

The number is useful anyway, because it is the only one I have to sort what needs eating first.

And with genuinely perishable things, the joking stops. Ground beef and fresh fish do not carry a best-before date, they carry a use-by date, and that one means it. Those are exactly the items I want to keep an eye on before I have to start sniffing a package.

We tried a note on the fridge door. The note itself expired after four days.

And there are plenty of pantry-tracking apps. But an app I have to actively open is an app I do not open. Certainly not at six in the evening with a pan in one hand.

So the problem was never missing information. The problem was that the information was never where the what-are-we-cooking decision actually happens.

So I built a fridge tracker

The first half of the solution is a small self-built web app.

After grocery shopping, everything gets scanned: barcode in front of the phone camera, the app pulls name and picture from Open Food Facts, I type in the expiry date, done. Over time it even learns how long a product typically lasts in our house and suggests the date right away.

For things without a barcode, like the fresh meat from a HelloFresh box, there is the photo path: take a picture, a vision model reads name, quantity, and expiry date off the packaging, and I confirm.

Confirm is the important word here. The AI may suggest, but it never writes anything silently. If the date was hard to read, it honestly says so. Same rule as my Gmail-to-Calendar automation: AI detects, I decide.

And when something leaves the fridge, there are exactly two buttons: eaten or thrown away.

More on that later. That button is meaner than it looks.

Why an e-ink display, of all things

Now the honest part: the app alone would not have solved the problem.

See above, apps have to be opened.

The list had to go where the decision happens: onto the kitchen wall.

That is exactly where the TRMNL BWRY now hangs. A 7.5-inch e-ink display that can do exactly four colors: black, white, red, and yellow. Hence the name. It runs for months on battery, does not glow, does not hum, and wants no attention. It just hangs there as a calm piece of information.

Four colors sounds like very little.

For a fridge, it is exactly the right amount: red means expired or due today. Yellow means the next three days. Everything else can stay black and white and quietly wait its turn.

At the very bottom there is a black bar with the next bin collection days: organic, recycling, paper, general waste. If a bin is due within the next two days, it gets a yellow highlight. That is also one of those things you somehow always need to know exactly when you are standing in the kitchen.

Technically, TRMNL is pleasantly open. There are ready-made plugins for calendars, weather, and the like, but also private plugins: the display fetches JSON from your own endpoint at fixed intervals and renders your own template. My endpoint serves the fridge list, sorted by due date.

The app behind it is a small Nuxt project and runs where my TypeScript things always end up: on Vercel.

What actually changed

The everyday effect is unspectacular, and that is exactly why it works.

You walk over for morning coffee and see in passing: two things due soon. Dinner surprisingly often gets planned off the display now. Fine, tonight it is the thing with the bell pepper.

• The information is where the cooking happens. No opening an app, no thinking, a glance in passing is enough.
• Red and yellow work instantly. Nobody reads tables on a kitchen wall. A colored edge on the row is plenty.
• One push a day, no more. Every phone can set its own time and its own look-ahead window. No notification machine-gun fire.
• The stats keep you honest. Eaten or thrown away turns into a waste rate and a small hall of shame of the most frequently discarded products.

That last point is the one that got me.

A number telling you what percentage of tracked food ended up in the bin does not argue. It just hangs there. And it has actually been dropping since the display went up, because the soon-to-expire things now get eaten instead of discovered.

The honest limits

The setup is good. It is not magic.

• Tracking stays manual. Every product has to be scanned or photographed. Stop doing that after two weeks and you own a very calm display with very wrong data.
• There is no magic camera in the fridge. Nothing automatically detects what goes in or out. The display only shows the truth you gave it beforehand.
• E-ink is calm, not fast. The display updates at fixed intervals, and a color refresh is a short, visible flicker. Completely irrelevant for an expiry list, fatal for real-time dreams.
• Without the tinkering itch, you miss the best part. The TRMNL works fine with ready-made plugins. But this exact fridge setup cannot be bought, it has to be built or copied.
• BWRY is a limited edition. If you cannot get one anymore: the regular black-and-white TRMNL does the same job, just without red and yellow. It works, but loses half the point.

Would I recommend it?

Yes, with one clear footnote.

The TRMNL BWRY is great for people who have a real recurring information problem and enjoy solving it with a small tool of their own. The fridge is my case. For others it is the calendar, the weather by the bike rack, or the train to work.

It is wrong for anyone expecting technology to solve the problem without any personal discipline. The display does not make anyone tidier. It just mercilessly shows how tidy you currently are.

For me, that is precisely the point.

The TRMNL does not make anything smarter. It just hangs the right information on the right wall.

And sometimes that is exactly what good stuff looks like.