Calorie scanner online: no app store, no install

How a browser can scan a barcode at all

This used to require a native app and no longer does. Three browser capabilities, all now standard, make it possible:

Camera access. The MediaDevices API lets a page request a live video stream after you grant permission. It is the same permission model as a video call — scoped to this one site and revocable at any time.

On-device decoding. Barcode detection runs on the video frames inside your browser, on your device. Frames are never uploaded. Only the decoded number — thirteen digits and nothing else — leaves your phone.

A database query. That number goes to the food database and the nutrition panel comes back.

The privacy consequence is worth being explicit about, because it is better than most people assume: an online scanner sends less data than an installed app. A web page cannot read your contacts, sit in the background, or track your location between uses. It gets a barcode number and nothing else.

What an online scanner does better

• Nothing to install. No download to scan one product in a supermarket aisle.
• Works on anything. Phone, tablet, laptop, a borrowed device, a work machine where you cannot install software.
• Always the current version. No app three updates behind.
• Shareable. A scan result is a URL. You can send someone a nutrition panel.
• No background anything. Close the tab and it has stopped existing.

What it cannot do

Two genuine limitations, stated plainly:

No notifications. A web page cannot reliably remind you to log dinner. If a daily nudge is what makes tracking stick for you, an installed app has a real advantage.

iOS wants Safari. Camera access inside third-party browser apps on iPhone has historically been restricted. If the camera will not open in Chrome on an iPhone, open the page in Safari and it will.

There is also no true offline mode, though this is less of a difference than it sounds — the barcode contains no nutrition data, so no scanner of any kind can return calories without a network connection.

Getting the camera working

Allow the permission when asked. If you dismissed it, the padlock icon in the address bar lets you re-grant it.

Check you are on HTTPS. Browsers only allow camera access on secure origins. Any real deployment of this site is HTTPS, so this mostly bites people running a local copy.

Close other apps using the camera. A video call holding the camera will block it.

On a laptop, use the phone instead. Laptop webcams point at your face, are low resolution and focus poorly at close range. A phone camera is dramatically better at this.

If the camera is unavailable for any reason, typing the digits from under the barcode does exactly the same lookup.

Saving your scans without an account

The diary works without signing in — entries are stored in your own browser, on your own device, and never reach us. That is genuinely private and genuinely fragile: clearing your browser data deletes it, and it does not follow you to another device.

An account exists for exactly that reason. If a diary that survives a new phone matters to you, sign in; if it does not, the anonymous version is complete.

Add it to your home screen

An online scanner can behave very like an installed app without being one. On iOS, tap Share then "Add to Home Screen"; on Android, the browser menu offers "Install app". You get an icon that opens straight into the scanner, full screen, with no browser chrome — and it is still just a web page, taking up no meaningful storage and needing no updates.

Open the online scanner.