Copyscape checks writing for plagiarism. It’s a must-use if you work with freelance content creators.

Frase and Surfer make it easy to create content briefs for your content writers. They also suggest additional keywords to include in existing content.

Grammarly spots grammatical issues and makes other suggestions.

WebFX’s Readability Test Tool grades how easy it is to read your content.

For even more, check out my full guide to 70+ useful content marketing tools.