It can be difficult to make the time to evaluate yourself as a remote worker, but a periodic check-in is important. If you work for a company, you may have a recurring process where you go through goal-setting and then performance evaluation against those goals. That's usually an annual process in bigger companies, but can be more informal and as frequently as monthly. Plus, you have to do much of the heavy lifting during this assessment period (read more about doing your own self-assessment in a meaningful way).
As an independent, the proof of your performance can be evident in your bank account. It's somewhat tongue-in-cheek, but then again not. If you're looking at your project commitments and you don't have trouble sourcing new work, something must be working! That said, it can be useful to evaluate yourself formally.
The technology doesn't have to be fancy in order for self-evaluation to work. Capture what your goals are, measure in the interim, then assess as pre-determined intervals. If you have a process by which you can capture feedback from clients (surveys being a popular choice), make sure you incorporate that feedback.
There's always informal feedback, too. It's hardly a scientific poll, but almost 2/3 of respondents in this poll don't go through a formal feedback process. If you're in this camp, you really need to be highly attuned to feedback and recognize it (and process it) when you get it.
It may not be packaged with a bow, as in "Hey, I have some feedback for you," but if you listen for it in your daily interactions, you can hear things from your clients, supervisor or team members that you might choose to work on.