This is a site on lots of different languages that I’ve come across before, but not made much use of. However, it came up when I was searching for a word online that I couldn’t find in the GPC, and as well as links to modern online dictionaries at the top of the page, it turns out to have a load of other links further down - - to older dictionaries, grammars, courses, the National Library of Wales, the William Morgan Bible, an edition of the Mabinogi and all sorts (I even saw @garethrking’s name mentioned, although I haven’t clicked through to see if it’s a pirated pdf or not). It’s not entirely error-free - - there’s a list of basic vocab at the end of the page that not only misses the final -s off Saesnes but also translates it into French as Anglaise – but there appears to be plenty of good stuff there.
Very interesting website! I clicked through on Gareth’s book to see what it had there and it’s now unavailable - 404 Document not found - so perhaps it was a pirated copy!