CSM (Certified Scrum Master), from Scrum Alliance, is one of the most popular Scrum certifications.
The problem with this certification is that you must attend a standard classroom course, which is not compatible with the aim of this website (providing information to those wishing to get certified by self-study), and I’m only mentioning it for the comparison purposes.
The course is two days long. Trainers are usually professional and provide a high-quality training. The course is more focused on creating an overall understanding of how Scrum works, instead of going through all the details that are common for PSM certification, and usually a few educational games are played during the course.
Most courses cost around $1500.
Participants take a short, simple online exam after the course, and prior to getting certified. The exam is very simple, and it’s not common for anyone to fail. Seemingly, the exam is mainly designed to evaluate the trainers rather then trainees.
The certificate is issued after passing the exam, and practically, can be considered a certificate of attendance rather than a certificate of completion.
It’s valid for one year. After that, you have to pay a $100 membership every year to renew your certificate.
The closest certificate to CSM is PSM I from scrum.org, which doesn’t require you to attend a classroom course, and is very common for those who prefer to self-study.