Telextext. (in 2021). Free and dead easy to use.
So happy I discovered this. I am a huge fan of Teletext and mourn its removal from UK TVs.
Here I show you a browser version I discovered and give a quick demonstration along with some wonderful original Ceefax tunes.
For the record, this also works on android phones/tablets and also I tested on Chromium on a pi zero!
Go here if you want to explore: https://zxnet.co.uk/teletext/viewer/