Toolbox is the biggest smart tool box app offers more than 80 tools like health tools APK sharing tool Flash Light and many other smart tools for daily use. This app is very popular between users and has always had score over than 4.
Some of the in-app categories are given below:
Health assistant tools:

Weight control
Heart rate
Eyesight test
Hearing test
Food Nutrition
...

Engineering tools:
Notebook
Calculator
Level
Protractor
Ruler
Seismograph

Multi media tools
Color detector
Painting canvas
Photo effect

Convertor tools:
Unit convertor
Text to Speech
World Clock

Measuring tools:
Illuminate
Stopwatch
Timer