Online learner dictionaries:
Macmillan
Longman
* Oxford Advanced Learner's Dictionary - n.b. to access the full features of this dictionary you should connect to the Unipd network via proxy.
Online corpora:
Skell - Sketch engine for Language Learning (also available for Italian, Russian, Czech and German)
English-corpora.org - The most widely used online corpora, including NOW, COCA, BNC and many more (corpora also available for Spanish and Portguese). You should register for this site for full benefit. Unipd has an academic site license.
Lextutor (Brown corpus - US English; BNC - GB English; etc.)
Internet corpora (online sources)
Corpus analysis tools
Antconc software suite
Online text analysers:
Analyze my writing - check the frequency of word classes in texts that you have written
Online dictionaries:
*Dictionaries available from unipd networked computers and via proxy.