Yes and passed the Certified Developer exam. There is also an administrator one.
It was one of the tougher certifications I have taken. In part because my preparation was not so good.
The certification should not be confused with the certificate for the free courses that MongoDB provide, which are good.
The Certified developer exam is as many other certifications, a paid for exam ($150). If you pass they will give you a link and reference number that can be used to verify the fact. It includes a free retake.
The exam is only available at certain times, quarterly is seems, for a period of a week.
The good news is that you can do it home any time of your choosing within that week, using special downloaded proctoring software.
The bad news is that that probably means a reasonable degree of tidying up. As you are required to scan your room, desk, both on top and beneath with a webcam, to check you have no reference materials to hand. Plus your microphone must be working. No one else to be in the room, no radios etc. If you have more than 1 screen, you will need to disable the extra ones, Skype must be turned off, basically they seemed to have thought out most of the ways people might try to cheat. No doubt they know how to spot people looking at the sheet they stuck on the back of the webcam, or looking at the book they hid down their trousers, since they want that you keep your head in view most of the time.
You will most likely be pushed to finish the exam with much time to spare and review the questions. Some of the questions are very wordy and you can spend over the average amount per question getting to understand the question.
I answered the last question with about 10-12 mins to spare. With no paper or pens allowed (whilst not specifically said, it is said that no reference materials allowed), its is hard keeping track of what you want to review. There is no neat summary of questions you have not answered or were unsure about.
Almost certainly you should take one of the introductory courses they offer for MongoDB development, there are 3. Apart from a few programming language specifics, the courses are fundamentally the same. There were no questions about java or node.js in the exam. Possibly some Python. I would recommend that the solutions to quizzes and the homeworks are reviewed, even if you got right. Note that after a course has ended, the answer videos become inaccessible, though the lectures remain accessible.
It has taken two and a half weeks for the results to come back from the closure of the exam period. They wait for the proctors to review the webcam footage (so wear something) and deal with any questions. Any suspicions activities may cause your result to be failed. The pass mark seems to be dependant on the perceived ease/difficulty of the exam.
Since the link to the certificate includes a photo of you taken as part of the verification process, it is probably worth doing looking reasonably smart and not in your dressing gown at 3am.
Specifics of topics are best covered by looking up the MongoDB site.