Free AI for ENEM essays: what each tool actually delivers

October arrives and ENEM pressure knocks at the door. The essay, always a score of 1000 in the candidate’s mind and frequently far below that in practice, remains the Achilles heel of those seeking admission to a federal university or ProUni scholarship. In 2026, however, there’s a real difference compared to previous years: text AIs have reached a level where they can correct, structure, and even simulate exam boards with a precision that previously only a good prep course teacher could deliver.

The problem is that dozens of tools are competing for attention, each promising to be “the best for ENEM”. This comparison focuses on what is free, accessible without VPN, and that truly works for the five evaluation criteria of Inep’s essay: command of formal Portuguese, understanding of the proposal, selection and organization of arguments, knowledge of linguistic mechanisms, and intervention proposal. If you want to know which AI to use as a serious training tool, you’re in the right place.

The short answer: ChatGPT (free version), Google’s Gemini, and Microsoft’s Copilot are the three options that deliver practical results for essay training at no cost. Each has a different strength, and understanding which matches your study style makes all the difference.

Comparison of main free AIs for essay writing

> Information based on official pages of each product in 2026. Models and free usage limits change frequently; always confirm on the manufacturer’s website.

Free ChatGPT: the most flexible for simulating the Inep exam board

OpenAI provides ChatGPT with access to the GPT-4o mini model on the free plan, with daily message limits that vary based on server time and demand. For essay training, this limit is rarely an issue: you submit your essay, ask for feedback, and work on rewriting. There are few interactions per session.

ChatGPT’s strength for ENEM is instruction flexibility. You can “program” the AI’s behavior with a well-written prompt. A practical example: “Correct my essay as if you were an Inep examiner for ENEM 2025, giving scores from 0 to 200 in each of the five competencies and explaining each deduction”. The AI follows the structure with reasonable accuracy, especially in competency 3 (argumentative coherence) and competency 5 (intervention proposal with agent, action, mode, effect, and detailing).

The real limitation is that GPT-4o mini tends to be more lenient than the exam board. It rarely fails an entire competency and usually inflates grades for essays with serious grammatical errors. To compensate, explicitly ask it to be strict and cite concrete examples of each deduction applied.

Gemini: best integration for those already using Google

If you use Gmail, Google Docs, or any Google service, Gemini is already practically in your workflow. The free version runs the Gemini 1.5 Flash model, which according to Google was optimized for speed and cost but delivers competitive text analysis quality for daily use.

For ENEM essays, Gemini has a practical differentiator: you can paste the text directly in the chat or, depending on integration available in Brazil, ask it to access a Google Docs document. Feedback by competencies works well when you instruct the model clearly. It’s especially good at competency 2 (understanding the proposal), identifying when the candidate strayed from the theme or addressed it tangentially.

Gemini’s free weakness is the tendency toward long, generic responses when not guided. If you simply paste the essay and ask “what’s wrong?”, you’ll get superficial analysis. The solution is always to use a structured prompt, like the example cited in the ChatGPT section, adapted for Gemini.

Microsoft Copilot: the most powerful on the free plan

Here’s something many people don’t know: Microsoft Copilot on the free version runs the complete GPT-4o model, not the mini. This means in terms of raw text analysis capability, it delivers more than free ChatGPT, which uses the reduced version of the same model. Microsoft doesn’t even require account creation for basic use, removing a barrier to entry.

For those wanting to correct essays without paying anything, Copilot is today’s best cost-benefit option in terms of model quality per zero dollars. Analysis of textual cohesion (competency 4) and grammatical mastery (competency 1) tends to be more detailed than free ChatGPT’s, precisely because of the base model’s greater capacity.

The disadvantage is in usage limits: Microsoft applies response number restrictions per session on the free plan. For a candidate doing multiple correction rounds in a single day, it may be necessary to alternate between tools. A good strategy is using Copilot for main feedback and ChatGPT or Gemini for refinement rounds.

Claude and Maritalk: options for specific cases

Claude from Anthropic, especially in the 3.5 Haiku model available for free, has a solid reputation for analyzing long texts and argumentation. For ENEM essays, which have a maximum of 30 lines, it works well. Claude’s differentiator is the ability to explain didactically why an argument doesn’t convince, which is useful for candidates struggling with competency 3.

Maritalk, developed by Maritaca AI with focus on Brazilian Portuguese, is an interesting alternative for those wanting an AI that understands the language’s nuances without the inaccuracies that models trained mostly in English sometimes present. Free access is limited, primarily via API (programming interface that connects systems, not the common chat interface), placing a technical barrier for most candidates. Keep an eye on Maritaca AI’s website for plan updates.

How to really use AI to train for ENEM essays

Having the tool solves nothing if you don’t know how to use it. The difference between using AI as a crutch and using it for actual training is in the method.

1. Write the essay without AI help. No assistance during text production. The goal is simulating real exam conditions.
2. Paste the text in AI with a competency-based feedback prompt. Ask for scores from 0 to 200 in each competency, with justification and examples from your text.
3. Read the analysis with a critical eye. Remember that AI tends to be lenient. If it gave 180 in grammar, reread your essay looking for errors it should have flagged.
4. Rewrite problem sections. Don’t ask the AI to rewrite for you; ask how to improve, and you make the correction.
5. Do a second round of analysis. Paste the corrected version and compare with the previous one.
6. Repeat the process with different themes. Consistency is what raises scores, not one perfect essay in isolation.

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Real limitations that no AI solves for you

None of these tools replace reading quality journalistic texts, building cultural repertoire over months, or genuine command of formal Portuguese. AI corrects but doesn’t teach from scratch. If you struggle with subject-verb agreement or nominal regency, you need to study grammar structurally before using AI as an evaluator.

Another important point: AIs don’t have access to Inep’s internal exam board criteria, which aren’t fully public. They simulate correction based on public information about competencies, but the final decision on failing a competency, for example, follows criteria that AI doesn’t replicate with fidelity. Use AI scores as relative reference, not as prediction of actual results.

Frequently asked questions about AI for ENEM essays

Can AI fail my essay on ENEM if I use it to write?

Inep detects theme deviation, blank essays, and violations of human rights to assign zero scores, but doesn’t have publicly declared technology for detecting AI-generated text as an annulment criterion. That said, writing essays with AI is ethically and pedagogically risky: you don’t develop competency and can be disadvantaged on the real exam. Use AI for training and correction, not production.

Which of these free AIs is better for someone starting from zero?

Gemini tends to be more accessible for beginners because many Brazilians already have Google accounts and the interface is familiar. Free ChatGPT is also a good entry point. Start with either and use the competency-structured prompt from your first session.

Can I use AI on mobile to train essays?

Yes. ChatGPT, Gemini, and Copilot have apps for Android and iOS available in Brazil. You can type or even dictate the essay and ask for feedback. The experience is slightly less fluid than on a computer, but works well for quick sessions.

Is Maritalk better than American AIs for Portuguese text?

Maritalk was trained with focus on Brazilian Portuguese and tends to present fewer interpretation errors regarding regional expressions and Brazilian cultural context. For practical essay correction use with current limited free access, American AIs still offer more convenience. But it’s worth following Maritalk’s development, which is a serious bet by the national AI community.

Which AI to choose based on your candidate profile

If you want the most powerful tool without paying anything, Copilot is the most rational choice in 2026, for access to complete GPT-4o on the free plan. If you prefer easy integration with your study environment, Gemini makes more sense, especially if you already use Google Docs to organize notes. If you want more control over AI behavior and already have experience with prompts, free ChatGPT delivers the necessary flexibility.

For candidates with specific argumentation difficulties, Claude is worth testing, even with free plan restrictions. And those interested in Brazilian-focused AI should keep an eye on Maritalk for the coming months.

Consistent training with any of these tools, done the right way, already puts you ahead of most candidates who still only correct essays with a teacher or, worse, never correct at all. The technology is there; the effort is still yours.