Thummer
Your phone locks the moment it leaves your hand.
Rest one thumb on the screen and use your phone normally. If a thief grabs it, Thummer blacks out the screen, asks for your fingerprint and locks your phone in seconds.
Three steps. One thumb.
Thummer watches one thing: whether your thumb is still on the screen. When a phone is snatched, it isn't.
Thumb in the bubble
Tap Start and a see-through water-drop bubble appears. Rest your thumb on it, lightly. It follows your thumb as you shift your grip.
Use your phone normally
Scroll, type, check maps and switch apps with your other hand. A small slip gets a short recovery window, so everyday use doesn't set it off.
Grabbed? It locks.
If your thumb leaves the screen, the display goes black and Thummer asks for your fingerprint. No fingerprint in 5 seconds? Your whole phone locks.
Thieves want your phone unlocked.
That's when your banking app, email and photos are open. Most security can't tell you holding your phone from someone taking it. Your grip can.
Thummer works alongside Android's built-in theft protection, which watches for motion that looks like a snatch. Thummer watches for something different: your grip being broken. Use both.
- Travelers using maps, tickets and cameras in crowded markets, stations and festivals.
- Commuters on trains, buses and platforms, and anyone who checks their phone at the curb.
- Students in a new city or studying abroad.
- Nightlife and event-goers heading out of concerts, games and bars late at night.
- Journalists and creators filming in crowds.
- Anyone whose phone holds their bank, their email and their life.
One plan, two ways to pay. No ads, ever.
- Cancel any time
- 7-day free trial
- About $2.50 a month
Billed through Google Play. Manage or cancel any time in your Google Play subscriptions. Prices shown in U.S. dollars; Google Play shows your local price.
Start your free trial on Google PlayFound a problem? Have an idea?
Thummer is new, and the people using it find things we can't. Tell us what broke, what confused you, or what you wish it did. We read every message.
Send feedbackOr email hello@thummerapp.com. Your phone model and Android version help us fix things faster.
Questions, answered.
Will it lock my phone by accident?
A small slip gives you a short recovery window, so normal use shouldn't cause locks. If your thumb fully leaves the screen, Thummer asks for your fingerprint first, so if it's you, one touch brings you back. Practice mode lets you get comfortable before you turn on live protection.
How long until it locks?
Five seconds after your thumb leaves the screen, unless you verify your fingerprint first.
Can a thief just put their own finger on the bubble?
No. Thummer stays bound to your original touch, and replacement touches are rejected.
Is this a fake lock screen?
No. Thummer uses Android's own device lock. Your normal PIN, pattern, password or fingerprint unlocks it.
Do I have to keep my thumb on the screen all day?
No. Turn Thummer on when you want it, such as on a train, in a market or walking to your car, and turn it off when you don't.
Does it work with face unlock?
Thummer needs a strong biometric. On many phones, including some Samsung Galaxy models, face unlock doesn't meet Android's strong-biometric standard, so you'll need a fingerprint enrolled.
What data does Thummer collect?
None. There's no account, no server and no analytics in the app. The only network use is Google Play handling your subscription. (This website counts visits and button clicks with Umami, which uses no cookies.) Read the privacy policy.
What permissions does it need, and why?
Display over other apps, to draw the bubble and the black screen; device administrator, limited to locking the screen; and notifications, to show protection is on. Thummer can't wipe your phone or read your other apps.
Does it replace Android's built-in theft protection?
No. Keep it on. Thummer adds a different layer that reacts to your grip being broken.
Does it work on iPhone?
Not yet. Apple restricts how apps can lock an iPhone, so an iPhone version will work differently. Email us and we'll let you know when it's ready.
Which phones has it been tested on?
Google Pixel 7a and Samsung Galaxy A54. It requires Android 11 or later, a screen lock and an enrolled fingerprint. If you run into trouble on another phone, email hello@thummerapp.com.
Covering phone theft?
Thummer is a patent-pending Android app that protects an unlocked phone at the moment it leaves its owner's hand. Founder Michael Harlow is available for interviews and live demonstrations.
Founder previously featured in CNN Business, the Los Angeles Times, the San Diego Union-Tribune, Latitudes & Attitudes, Savvy Retiree and Outdoorsy.