flaggeronline.com provides OSHA Flagger Certification Online. Visit our website today for more information. The Flagger Certification course grants you the ability to work as a certified flagger as required by the department of transportation and MUTCD. By law, all flaggers must be properly trained in flagging operations and flagging procedures by a certified flagger training instructor. By completing the flagger certification course you will acquire a strong knowledge of proper flagging techniques and be ready to work on the job as a work zone flagger.