What's the best free AI for writing essays?

For essay-style writing on the free tier, Claude Sonnet 3.5 is usually the better choice. Anthropic models tend to:

• Write longer, more structured paragraphs out of the gate
• Hold a thesis across multiple paragraphs without drifting
• Produce prose that reads less like "AI" (more variation in sentence length, fewer hedging clauses)

ChatGPT 4o is faster and friendlier for brainstorming and outlining. A solid workflow: outline with 4o, draft with Claude 3.5.

If you upgrade to Pro, Claude Sonnet 4 is a step up again, usable for actual publishable writing with light editing.

Whichever model you use, give it the assignment brief, not just the topic. "Write about the causes of World War I" produces a generic survey; "1,500-word argumentative essay for a first-year history course, thesis: alliance systems mattered more than the assassination, cite at least four specific events, formal but not stuffy" produces something you can actually work with. Length targets, audience and required structure are the three details students most often leave out.

One hard warning for academic work: chat models will invent plausible-looking citations, complete with fake page numbers and DOIs. That's a known failure called hallucination, and it has embarrassed people in courtrooms and journal submissions alike. Have the AI structure your argument and polish your prose, but pull real sources yourself or verify every reference it suggests before it goes in the bibliography.