Here’s a list of websites I find useful in writing research papers in English.
Any feedback and suggestions are always welcome!

[Writing support tool]
WriteAway
As you type some words, WriteAway shows patterns (and examples) frequently used in written discourse.

[Word usage]
Lexipedia – Where words have meaning
Just The Word

[Dictionary/Thesaurus]
Memidex – free online dictionary and thesaurus
OneLook Dictionary Search

[Corpus]
Corpus of Research Articles
Springer Exemplar
StringNet Navigator 4.0
Sketch Engine: Open corpora
The Corpus of Contemporary American English (COCA)
BYU-BNC: British National Corpus

[Online proofreader]
Online Proofreader: Pre-Grade Your Essay | Paper Rater
Academic English Marking Mate