Yes, they are. I haven’t heard of otherwise. However, many have time limits that can range from 1–6 months. Some of the more popular ones are only 2–3 months.
So that can put you in a pinch.
And then if you consider the fact that most people take courses before they teach abroad then by the time they actually get abroad and start teaching their access to the course will be terminated.
Now that might be fine if all you want to get is a certificate, but what if you want to learn?
If you want to learn then I have to say that learning takes repetition and time. Even if you take an in-class course that course is limited by time and it's a one time deal. But chances are you won't remember all of it and that is especially true of many online courses as many people do not remember what they learn.
See the research.
There are 2 types of online courses
Type 1 is "synchronous".
This means that the online course takes place at a certain time and like in-class courses classes they tend to be scheduled. I have never heard of this kind of online course with TEFL.
A university may have this kind of course, but not that one that says it's ran by the University of Toronto, that's ran by a recruiter and it's an "asynch" course.
Type 2 is "asynchronous".
That means that there are no such class times and schedules. A course that says "learn at your own pace" or that it is "self-paced" means that these courses are asynchronous. Most online TEFL courses will be this way.
I have never heard of an online TEFL course doing differently.
How long do courses take to complete?
Many people complete many of those online TEFL courses in less than 20 hours and not like 120 or 150 "hours" like they say.
Learn more about TEFL course "hours".
What's the best option for you?
The best option is unlimited access to a course. That means you will have the most flexibility and you will be able to work on it as you see fit.
And that will also be optimum for learning. After you start teaching you can revisit parts of the course to get ideas for classes and you can review content as needed.
You won't have to rush or worry about getting locked out.
ESLinsider's Advanced course includes lifetime access.