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Top Cool, Useful, and Free Androids Apps (apk)

Updated on July 19, 2016

Turn Your Phone Into a (fill in the blank)

Nearly everyone knows that smart phones can play games. If you have one, you probably also know that they can scan QR codes - those complex little images that Rorscach might have dreamed up - to automatically load web pages or download apps. In fact, smart phones combined with some clever applications are capable of detecting metal, measuring size and distance, monitoring your heart rate, and more. What follows is a list of cool, free apps that can give your Android device some amazingly useful features. Most are available from Google Play or the Amazon App Store.

Scanner Radio

Scanner Radio lets you listen in on Police, Fire, and Emergency radio communications.
Scanner Radio lets you listen in on Police, Fire, and Emergency radio communications. | Source
Download Scanner Radio
Download Scanner Radio

Turn Your Phone into a Police / Emergency Scanner

Scanner Radio is an app that connects to and relays emergency radio broadcasts. Listen to police, fire, emergency, and amateur radio transmissions from local agencies or anywhere in the country. If you give it permission to do so, the app will use your current location to help you identfy local streams, or you can search by location and type (police, fire, weather, etc.).

This application requires wifi or a data plan.

Scan and Copy Documents

Download CamScanner
Download CamScanner
Download PrintBot
Download PrintBot

Turn Your Android Device into a Document Scanner / Photocopier

Documents, receipts, and even whiteboard presentations can easily be scanned and concerte to PDF files with the help of CamScanner. This app uses your phones camera plus some specialized software to clarify the scanned image and generate a PDF document.

There are a lot of applications that allow document printing, most of which use a hosted service like Google's Cloud Print, or require a PC to relay the print job to a printer. I wanted a solution that would not require a separate service or a PC, so I chose PrintBot. This app has drivers for most printers, and supports sending office documents, PDFs, and images directly from an Android device to a network-connected printer over wifi. The free version of PrintBot has a limt of three print jobs per month, but can be upgraded to the unlimited pro version for under $5.00. The combination of CamScanner plus PrintBot makes a smartphone into an effctive photocopier.

Instant Heart Rate

Instant Heart Rate Screenshot
Instant Heart Rate Screenshot | Source
Download Instant Heart Rate
Download Instant Heart Rate

Use Your Phone to Measure Your Heart Rate

Making ingenious use of camera technology, Instant Heart Rate measures one's heart rate or pulse. Have you ever put your finger over the end of a flashlight? You can see light passing through your skin around the edges. To use Instant Heart rate, you put your finger over the camera lens, and the app not only detects the light around the edges, but can actually determine when your heart beats based on the changes in the speed of blood-flow. This award-winning app is remarkably accurate, at least if my tests taking my own pulse with a stop-watch is any indication. This application works best on devices with a camera flash, but will work without a flash in sufficient ambient light.

Measuring Distance and Height

Download SmartMeasure
Download SmartMeasure

Your Phone can Measure Height and Distance

In another clever use of camera phone technology, SmartMeasure uses telemetry to measure the distance of an object from the device. You focus on the ground or floor at the base of an object. You can then focus on the top of the object, and SmartMeasure will return its height. The application is fairly accurate but I wouldn't count entirely on it where absolute precision is required. Also, the device's accuracy can be improved by calibrating a few settings. The basic application is free, but if you also want to measure width and area in addition to height and distance, you can upgrade to the Pro version for a whopping 99 cents.

Android Metal Detector

Metal Detector Screenshot
Metal Detector Screenshot | Source
Download Metal Detector
Download Metal Detector

Turn Your Phone into a Metal Detector

Can your phone really become a metal detector? There are several free apps available that claim they can do just that. I installed two of them on my phone, Metal Sniffer and Metal Detector, the second of which is marketed by the same group that brings us SmartMeasure. Both programs actually detect the proximity of metal on my Galaxy S II. Neither one would pick up the small finishing nails in paneling, but when I waved the phone over a section of wall where I know there is a bundle of electrical wires, both applications indicated a marked change in magnetic field strength. Incidentally, both applications were completely capable of finding handguns and large knives under a layer of clothing. Small knives (like a regular jack-knife) were considerably harder to detect.

These programs use the magnetic sensor in phones, and as there authors state, their accuracy is entirely dependent on these sensors. Of the two, I liked the interface of Metal Detector slightly better, because the changes in magnetic field strength is displayed a bit more dramatically.

Download Ultra Magnifier +

Turns your smart phone into a magnifying viewer.
Turns your smart phone into a magnifying viewer.

How To Use Your Phone as a Magnfiying Glass

There are several applications on the market that will magnify images using the camera technology of smart phones. The one I reviewed is Ultra Magnifier +. These applications use the camera's zoom functionality as well as software to enhance the image. Unlike a real magnifying glass, Ultra Magnifier + enlarges the image as you move the phone closer to the subject, but about 5 or 6 inches from the object seems to be the ideal distance in terms of magnification and focus. Its great for reading fine print.

Some reviewers complained of blurry images. I've found that the application performs much better in good light. I wonder if a future version will let you use the camera's flash to illuminate the subject. Also, I did have a fuzzy image a few times, but simply moving the camera away, then moving it closer a bit more slowly allowed the auto-focus to start over, and the picture cleared right up. I was able to clearly read the fat content listed on the package from the GooGoo Cluster I'd just eaten. Kind of wish I hadn't read it.

Radiation Detector

Download GammaPix Lite
Download GammaPix Lite

Your Phone as a Geiger Counter

There are dozens of "gag" Geiger counters available that will show high levels of radiation to scare and fool your friends. While I would not find that amusing myself, there is at least one application that will apparently detect ionizing radiation. This is the only application in the round-up that I did not test personally, primarily because I didn't want to go through the 20-minute calibration that is necessary for good results. If I lived in Japan or near any kind of nuclear facility, I would probably invest the time. GammaPix Lite uses the digital camera to detect radiation. You have to cover the camera lens with electrical tape to block out light, the radiation easily penetrates the tape and is detected by the application. Reviews are mixed, but users with newer phones having better cameras generally report success, using old radium watches and smoke detectors (both of which give off radiation) to test their phones radiation-detection capability.

The Phone as a Tricorder?

With the ability to find metal, measure radiation, determine size and distance, and monitor heart rates, the phone is evolving ever closer to the capabilities of the tricorders from Star Trek. The fact is there is a "tricorder" application ("Tricorder-5.12-1.apk"), but CBS made Google take it off the market for copyright infringement. Not that the term "tricorder" was used incorrectly - Gene Roddenberry granted the use of that term years ago. It was the curved menu interface that CBS claimed was theirs. So the application was removed for violating the copyright of a user interface that never actually existed. This app can measure gravitational force ("G"s), magnetic fields (like the metal detector apps), and scan for cellular and wireless signals, among other things. It is a fun app for us Trekkies.

Even though the tricorder app is no longer available, there is a plethora of applications that give your phone most of the same capabilities plus a lot more. Even if you don't really need them, they're great ways to show off your smart phone. Go ahead - grab a few and start impressing your friends.

For more great Android applications, please see this list of top 10 apps to install on a rooted Android device.


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    • ChristyWrites profile image

      Christy Birmingham 

      8 years ago from British Columbia, Canada

      How cool! I did not know about the magnifying option. Thanks!


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