Why choosing the right AI makes a difference in your essay grade
Writing a good essay for ENEM is not just about organizing ideas. You need to master the essay-argumentative structure, build a detailed intervention proposal, use sociocultural background in a relevant way, and maintain coherence from beginning to end. There are five competencies evaluated, each worth up to 200 points, and any slip in one of them already compromises your final grade.
The good news is that in 2026 there are free artificial intelligence tools capable of really helping with this process. Not to write the essay for you, which would be dishonest and ineffective for learning, but to review, suggest background material, point out cohesion flaws (the mechanisms that connect ideas in the text) and simulate an evaluating board. The bad news is that not all AIs perform well in these tasks, and choosing the wrong one can make you waste valuable time.
In this comparison, you will find an honest analysis of the main free options available to Brazilian students in 2026, with a focus on practical use for the ENEM essay.
General comparison of free AIs for essay writing
| Tool | Free limit | Native language | Evaluates ENEM structure | Corrects cohesion | Suggests background |
|---|---|---|---|---|---|
| ChatGPT (OpenAI) | Yes, with GPT-4o mini | English, but accepts Portuguese | Yes, with proper prompt | Yes | Yes |
| Google Gemini | Yes, version 1.5 Flash | Multilingual | Yes | Yes | Yes |
| Microsoft Copilot | Yes, no registration | Multilingual | Partial | Yes | Partial |
| Claude (Anthropic) | Yes, Haiku version | Multilingual | Yes, with instructions | Yes | Yes |
| Maritaca AI (Sabiá) | Yes, limited use | Brazilian Portuguese | Yes, native | Yes | Yes |
Important: free usage limits change frequently. Check the current conditions directly on the official websites of each platform before relying on one of them.
ChatGPT: does the most popular option still deliver?
ChatGPT, from OpenAI, continues to be the most well-known tool on the market. In the free plan, access is to the GPT-4o mini model, which is competent for language tasks but has lower performance than the full GPT-4o, available only in paid plans.
For ENEM essay writing, ChatGPT works well when you give clear instructions. A prompt like “You are an ENEM essay teacher. Evaluate my text on the five competencies and point out specific flaws” tends to generate useful feedback, with comments on thesis, argumentation, cohesion, and intervention proposal. Without this kind of instruction, the response can be too generic to have pedagogical value.
The weak point here is sociocultural background. ChatGPT sometimes suggests references that sound good but are superficial or poorly suited to the ENEM board, which values data from reliable sources, legislation, established thinkers, and historical situations. It’s worth checking each suggestion before using it.
How to use ChatGPT for ENEM in practice
- Paste the official essay topic and ask the AI to explain the context and possible approaches.
- Write your essay without AI help, the way you would on the test.
- Paste the text in the chat with the evaluation prompt by competencies.
- Ask for improvement suggestions for each paragraph identified as weak.
- Rewrite with your own words, using the feedback as a guide.
Google Gemini: good integration with current sources
Gemini, from Google, has a clear advantage over competitors: access to more recent information through integration with Google Search, depending on usage mode. This is relevant for ENEM essays because it allows you to search for recent data on the proposed topic, such as statistics, news reports, or expert statements.
In the free plan, Gemini 1.5 Flash is fast and handles text review tasks well. For evaluating ENEM structure, it responds well to specific prompts, identifying when the intervention proposal is incomplete (one of the most common and most penalized flaws in Competency V). The response in Brazilian Portuguese is fluent and appropriate for the educational context.
An important limitation: free Gemini sometimes errs in interpreting ENEM board nuances, especially in Competency I, which evaluates command of formal language. It may let pass constructions that would be questioned by an experienced teacher. For fine grammatical review, it’s better to complement with another resource.
Claude, from Anthropic: best for deep textual analysis
Claude, developed by Anthropic, has a characteristic that stands out for educational purposes: it tends to give more structured and analytical responses than competitors. The free model, Claude Haiku, already delivers fairly useful critical reading of the text.
When asking for an essay evaluation with specific ENEM structure, Claude usually presents the feedback in an organized way, pointing out the problem, the paragraph where it appears, and a concrete suggestion. This level of detail is rare in free plans from competitors. For students who want to understand the “why” of errors, not just the “what,” this approach makes a real difference in learning.
The message limit in the free plan can be an obstacle. In long review sessions, you may hit the ceiling quickly. The solution is to work paragraph by paragraph instead of pasting the entire text at once.
Maritaca AI and the Sabiá model: the Brazilian difference
Maritaca AI is a Brazilian company that developed the Sabiá language model, trained with special focus on Brazilian Portuguese and national content. This training difference matters: the model understands Brazilian expressions, local cultural references, and the context of ENEM with a naturalness that American models don’t replicate with the same precision.
For sociocultural background specific to Brazil, such as IBGE data, national legislation, Brazilian literature authors, and recent historical events in the country, Sabiá tends to be more accurate and contextualized than ChatGPT or Gemini. This is a concrete advantage when suggesting references for the essay.
Free access has usage limits, and the platform doesn’t yet have the same popularity as American tools, so the community of tutorials and ENEM-specific tips is smaller. But for those who want an AI that truly “speaks the language” of the Brazilian student, it’s worth exploring. Check the current conditions on Maritaca AI’s official website.
Microsoft Copilot: it works, but it’s not the focus
Copilot, from Microsoft, has the advantage of working without registration in a basic version, which is convenient for those who want to test quickly. It uses OpenAI technology underneath, but with Microsoft’s own settings.
For ENEM essays, Copilot works reasonably well, but it’s not the most efficient choice. Responses tend to be shorter and less detailed than ChatGPT or Claude in textual evaluations. It’s more useful for quick research about the essay topic context than for pedagogical review of the text itself.
What no free AI does well
All the tools mentioned have limitations you need to know about before relying on them. None of them replace an experienced human teacher in the ENEM board. Language models can err in evaluating the appropriateness of sociocultural background, which is one of the most subjective criteria and most valued by actual correctors.
Also, AIs tend to be too permissive with user text when they don’t receive critical evaluation instructions. Without the right prompt, they congratulate mediocre essays instead of pointing out problems. Learn to explicitly ask for tough feedback.
Another point: data and statistics suggested by AI should always be verified in primary sources, such as the official IBGE website, IPEA reports, or ministry portals. Using incorrect data on the test can hurt Competency I and Competency III at the same time.
If you want a suitable device to use these tools without lag, check the best phone up to 2000 reais in May 2026 for an updated comparison of affordable options with good performance in AI applications.
Which AI to choose by student profile
- Want detailed and pedagogical feedback: Claude, with specific prompts by competency
- Need updated background and recent data: Google Gemini, with search mode enabled
- Want genuinely Brazilian cultural references: Maritaca AI (Sabiá)
- Prefer the most popular tool with more available tutorials: ChatGPT with custom prompts
- Don’t want to create an account on any platform: Microsoft Copilot, as a starting point
The most efficient strategy for those who take ENEM seriously is to use at least two different tools, one for generating background and context, another for structural review of the text. They complement each other and cover each other’s gaps.
For students who use their phone as their main study device, it’s worth checking how to choose a good and cheap phone in 2026 to ensure the device handles intensive use sessions of these tools well.
Frequently asked questions about free AIs for ENEM essays
Can I use AI to write my ENEM essay?
On the official test, no. ENEM is conducted on paper, without access to electronic devices. Using AI in the study process, as a review and learning tool, is a legitimate and growing practice, as long as you don’t copy the generated text without your own elaboration.
Can the AI give a grade for my essay like the ENEM board does?
Not with real accuracy. AIs can simulate an evaluation by competencies, but they don’t replicate the human criteria of the official board, especially in Competency II (thematic competency) and Competency III (appropriateness of background). Use the feedback as a reference, not as a definitive grade.
Do I need to pay to access the best features?
For use in the ENEM context, the free plans of the main tools are sufficient if you use well-constructed prompts. Paid plans offer more powerful models and higher limits, which is relevant for those who use daily in long sessions, but it’s not essential for most students.
Do AIs make grammatical errors in Portuguese?
Yes, and this is a relevant problem for those who use texts as models. Models trained predominantly in English, such as ChatGPT and Claude, can produce constructions that sound strange in formal Portuguese. Always review with a critical eye and, if in doubt, consult a reference grammar or a teacher.
The verdict for those studying now
There is no perfect free AI for ENEM essays. What exists is a smart combination of tools, each one used for what it does best. Claude stands out in structural analysis; Gemini, in accessing current context; Sabiá, in mastering the Brazilian universe. ChatGPT balances both sides well when you invest in quality prompts.
The most important thing is still the same as always: write a lot, receive real feedback, and understand the board’s criteria. AI is an accelerator of this process, not a substitute. Use these tools well, and they will help you arrive at the test with much more confidence.