Can you use Pleco online?
Pleco is the go-to Chinese dictionary app for many Chinese learners. It has been around for a long time and has a lot of features that make it a great tool for studying Chinese. I have personally spent hundreds of hours with Pleco and although it's not perfect, my Chinese would not be the same without it.
Unfortunately, it only provides apps for iOS and Android. There is no official Pleco app for Windows, macOS, Linux, or web. Other popular Chinese dictionary apps, like Hanping or Hanzii, also don't have web versions.
Let's look at some web-based alternatives that you might want to consider.
MDBG
MDBG has been around forever and is the first search result you'll find when looking for an online Chinese dictionary. It provides a lot of information, but comes with a slightly retro and rather overloaded UI. Furthermore, the search experience is not as smooth as you might be used to if you usually use Pleco. You won't see search results until you hit the search button, which can be a bit annoying if you are used to mobile apps that show you results as you type.

Written Chinese
The Written Chinese website seems abandoned with several unavailable pages. However, the online dictionary is still working and it's definitely prettier than MDBG. It provides a lot of useful information, like example sentences and radicals, but also doesn't show results as you type.

Chill Chinese
If all you want is something like Pleco that you can use while on your computer, this is what you are looking for. It's super smooth, super pretty, and shows you search results instantly as you type. It does not yet have all the features that the aforementioned two dictionaries have, but we are working on it. Give it a try and let us know what you think :)
