CDL Prep Test 2021 All-in-One Lite is an Android application that aims to help commercial driver's license (CDL) test takers pass their written test with confidence. Developed by Webrich Software, this free app contains over 500 test questions with multiple-choice answers. It simulates the written test and provides a detailed score at the end, which can be emailed to the user for further review.

The CDL test questions are presented in random order, ensuring that they will not be repeated in the same test. The latest test scores are also saved automatically, allowing users to track their progress over time. The app covers all the categories one needs to study to pass the written test, including rules of the road, air brakes, HazMat, passenger vehicles, safe driving practices, combination vehicles, doubles and triples, pre-trip inspection, and tank vehicles.