COCA (English-Corpora.org)
Search a billion words of real American English to settle usage questions.
What it actually is
The Corpus of Contemporary American English lets you ask which words actually collocate with which, whether a phrasing is common in academic writing but rare in speech, and how usage has shifted over decades — evidence rather than opinion, which is exactly what advanced writers need. Free after a quick registration, with sister corpora for British English, news and academic text. The interface is academic and unfriendly, free accounts hit query limits, and it assumes you can interpret concordance lines, so it is genuinely a C-level tool.
What it covers
- Writing
- Vocabulary
- Grammar