Fluency and Coherence
• Discourse marker list
https://dictionary.cambridge.org/grammar/british-grammar/discourse-markers-so-right-okay
Lexis
• Online Collocation Dictionary
https://www.freecollocation.com/
https://www.macmillandictionary.com/browse/collocations/british/a/
• Online Idiom Dictionary
Grammar
• Basic grammar
Pronunciation
• Spoken English Corpus
https://corpus.eduhk.hk/esl_learner_corpus/#/home
• English Pronunciation learning website