How to chat with PDF documents using AI for students research and legal review

To chat with a PDF using AI, open a text-based PDF in a chat-with-PDF tool, ask specific questions that point to sections or terms, and check every answer against the page it came from before you rely on it. Scanned documents need OCR first, and confidential legal files should not go to a cloud AI service unless you are allowed to share them.

Chat-with-PDF tools turn a long document into something you can question in plain language: "What does clause 9 say about termination?" or "Which method did the authors use?" Used carefully, they save hours of scrolling. Used carelessly, they can produce confident mistakes. This guide covers how these tools work, how students and legal reviewers can use them well, and what to keep out of them.

Key takeaways

• A chat-with-PDF tool reads the text layer of your PDF and sends that text to an AI model to answer questions. Scanned PDFs have no text layer until you run OCR.
• Siliph's Chat with PDF extracts text in your browser and reads up to the first 60 pages. The extracted text is then sent to an AI model provider, which the privacy policy names as DeepSeek, with Google Gemini as a fallback.
• Always verify quotes, numbers, dates and citations against the original page. AI tools can state wrong information confidently.
• For legal material, think about confidentiality before uploading. Kerala's High Court barred district judges from putting case documents into cloud AI tools in 2025.
• Use chat for questions and a summarizer for an overview. The two work best together.

How chat-with-PDF tools work

The tool pulls the words out of your PDF, then gives those words and your question to a language model. It does not "understand" the file as a picture. That has three practical consequences:

1. Scans need OCR. A scanned judgment or photographed notes are images, so there is nothing to extract. Run OCR PDF first. It adds a searchable text layer and supports languages including English and Hindi.
2. Length is limited. Tools cap how much text they send to the model. The Chat with PDF tool reads up to the first 60 pages, and very long text is shortened before it is sent. For a long thesis or a paper book, split it by chapter or volume with Split PDF and chat with one part at a time.
3. Layout can get lost. Tables, footnotes and two-column layouts sometimes come out in a jumbled order. If an answer about a table looks wrong, check the table yourself or extract the plain text with PDF to Text to see what the model actually received.

Compressing a PDF does not help a chat tool. The model only sees the extracted text, so file size matters only for how long your browser takes to open it.

Using it for student research

Ask targeted questions, make the tool point to where the answer is, then read that part yourself. Useful prompts for a research paper or thesis:

• "List the research questions and the page where each is stated."
• "Summarise the methodology section in five bullet points, using the paper's own terms."
• "What limitations do the authors mention?"
• "Which datasets or sample sizes are reported? Quote the sentence for each."
• "Explain this paragraph in simpler language: [paste the paragraph]."

For a first overview, the AI PDF Summarizer gives a short summary, key points and action items in one pass. Then switch to chat for follow-up questions.

Check your institution's rules before you use AI in coursework. UNESCO's guidance for generative AI in education and research calls for protecting data privacy and notes that institutions are largely unprepared to validate these tools. The responsibility for checking an AI answer therefore sits with you.

Using it for legal review

AI chat is useful for finding and comparing clauses, and unreliable as a final authority. Reasonable uses include:

• Locating clauses: "Where does the agreement deal with indemnity, and what are the caps?"
• Checking definitions: "How is 'Confidential Information' defined, and what is excluded?"
• Building a timeline: "List every date mentioned in this order with the event it refers to."
• Comparing versions: ask the same question of two drafts and read both answers against the text.

Two real cases show the limits. In Mata v. Avianca, a US federal judge fined two New York lawyers and their firm US$5,000 after they filed a brief citing six non-existent cases generated by ChatGPT, as the ABA Journal reported in June 2023. In India, a Kerala High Court policy reported in July 2025 bars the district judiciary from using AI tools to reach findings, reliefs, orders or judgments. According to MediaNama, the policy also bars sending case facts, personal identifiers, privileged communications or documents to cloud-based AI tools, and requires all AI output, including citations, to be verified.

The policy applies to judges in Kerala's district courts, not to lawyers or students, but its reasoning is a good checklist for anyone handling client files.

What not to upload

Do not put a document into a cloud AI tool if you are not allowed to share it with a third party. With the Chat with PDF tool, the text extracted from your PDF goes to an AI model provider to generate answers. The site's privacy policy names DeepSeek, with Google Gemini as a fallback, and advises against using AI features for documents you may not share with these providers.

A simple workflow that works

1. Check the text layer. If you cannot select text in the PDF, run OCR first.
2. Trim to what you need. Keep only the relevant chapters or annexures with Extract Pages.
3. Ask one question at a time. Ask for the section or page and a short quote with each answer.
4. Verify. Read the cited part of the original. Treat anything you cannot find as unconfirmed.
5. Keep your own notes. Record what you verified, so your final work rests on the source, not the chat.

The Chat with PDF tool is free with no sign-up, and fair-use hourly limits apply.

Frequently asked questions

Can AI chat with a scanned PDF?

Not directly. A scan is an image with no text layer, so the tool has nothing to read. Run OCR first to create a searchable PDF, then chat with that version.

How long can the PDF be?

The Chat with PDF tool reads up to the first 60 pages of text, and very long text is shortened before it is sent to the model. Split long documents by chapter for better answers.

Is it safe to chat with confidential legal documents?

Only if you are permitted to share them with the AI provider. With the Chat with PDF tool, the extracted text is sent to an AI model provider, so do not upload privileged or client documents without permission.

Can I trust the AI's citations and quotes?

No, not without checking. Courts have penalised lawyers for filing AI-generated citations to cases that do not exist, so confirm every citation and quote in the original source.

What is the difference between chatting with a PDF and summarising it?

A summarizer gives one structured overview of the whole document. Chat lets you ask follow-up questions about specific parts. Many people summarise first and then chat.

Sources

• ABA Journal: Lawyers who doubled down and defended ChatGPT's fake cases must pay $5K, judge says
• MediaNama: Kerala High Court bars AI tools such as ChatGPT and DeepSeek in district judiciary
• UNESCO: Guidance for generative AI in education and research
• Siliph: Privacy policy (AI features and model providers)