CDL Prep

Study for commercial driving tests

CDL Prep is an education app for people preparing for a Commercial Driver’s License written exam. It covers general commercial knowledge along with endorsement subjects including air brakes, combination vehicles, hazardous materials, passenger vehicles, tanks, school buses, and doubles or triples.

Two ways to practise

The app includes more than 500 practice questions. In Practice Mode, you answer one question at a time and get immediate feedback when your answer is incorrect. Exam Mode is designed to feel more like a timed test: the general section gives you 50 randomly selected questions over 60 minutes, while endorsement tests use 20 to 30 questions over 40 minutes.

Useful feedback as you go

After an exam, you can check your score and review questions answered incorrectly. CDL Prep also tracks performance for individual questions, making it easier to see which areas need more work. Results are grouped by average performance: red indicates below 70%, orange covers 70% to 89%, and green indicates 90% or higher. Answer choices are shuffled between questions, so studying requires knowing the material rather than relying on a fixed position.

A focused revision tool

This is a practical choice for learner drivers who want a broad question bank and a simple way to measure progress across several CDL topics. It is less suited to someone looking for lessons, driving simulations, or general transport information. Developed by Jeffrey Diaz, CDL Prep has a 4.612 rating from 5,423 reviews and more than 1,000,000 installs, suggesting that it has become a familiar study companion for CDL candidates.