与 PDF 对话：向您的文档提问并获得答案

You've got a 100-page PDF. You need to find one specific piece of information — a date, a name, a policy detail. You could scroll through every page, squinting at the text, trying to remember if that clause was on page 47 or 72. Or you could just ask.

Chat with PDF is an AI-powered tool that lets you ask questions about your PDFs. It uses the extracted document text to generate answers to your questions. You can ask follow-up questions, but the answers should still be checked against the source when details matter.

The difference between this and traditional search is the difference between a flashlight and a conversation. Search is good if you already know exactly what you're looking for. But if your question is vague, or if the answer isn't a single word, search fails. The model receives the extracted text supplied with each request, so a question can refer to information appearing in different parts of the available text.

工作原理

The tool sends your extracted document text to the AI along with each question you ask. There's no separate indexing step — the full extracted text is included every time, and the AI answers directly from that text.

• Upload: You upload your PDF. It stays in your browser — more on that below.
• Prepare: The extracted text is sent to PDFly's server, which forwards it to Google Gemini along with your question each time you ask one.
• Ask: Type any question about the document. No special syntax required — just plain English.
• Follow up: You can ask additional questions in the same conversation; recent turns are included with the next request.
• Answer: The AI provides a direct answer based only on the document's text.

What you're actually seeing here is a technology that only recently became widely available. The tool is designed for document questions without requiring a separate document-indexing step: the extracted text is included with each question sent for processing.

您可以提问的内容

The range of questions you can ask is broader than you might expect. Here are some examples to give you a sense of what's possible:

• Specific facts: "What's the deadline in section 3?" "Who is listed as the primary contact?"
• Summaries: "Give me a summary of the main findings." "What are the key takeaways from this report?"
• Comparisons: "How does this year's numbers compare to last year?" "What changed between version A and version B?"
• Lists: "List all the action items in this document." "What are the requirements listed in the appendix?"
• Contextual questions: "Why was this decision made?" "What is the rationale behind this policy?"

The AI works particularly well with documents that have a clear structure: contracts, reports, academic papers, and technical documentation. It can handle messy documents too, but the quality of the answer depends heavily on the quality of the source material. If the PDF is a scanned image with poor text recognition, the answers will reflect that.

When to use Chat with PDF (and when not to)

This tool shines in specific scenarios. If you're reading a long academic paper and you just need to verify a specific concept before you cite it — this is faster than any keyword search. If you're reviewing a contract and you need to know whether there's a non-compete clause hidden somewhere in the fine print, this is the tool you want.

However, it's worth being clear about what it doesn't do. It doesn't analyze images or charts — if the answer is in a graph, you still need to look at the graph. It doesn't make judgments or decisions — it answers questions based on what's in the document, but it doesn't evaluate the quality of that information. And it doesn't have knowledge beyond your document — you can't ask it about something that isn't in the PDF.

The tool also has a practical limitation: very large documents with hundreds of pages can sometimes cause processing times to stretch beyond what feels instant. Large PDFs can take longer to extract in the browser, and only the first 40,000 characters of extracted text are available to the AI.

关于隐私的说明

Your PDF itself is never uploaded — the file is opened and its text extracted locally in your browser. That extracted text, along with your question, is then sent to PDFly's server, which forwards it to Google's Gemini API to generate an answer. This is worth being clear about: it's not fully local processing, but it's also not the same as uploading your original file wholesale. If a document contains information you don't want leaving your device at all, this tool isn't the right fit — PDFly's non-AI tools (merge, split, compress, and similar) process everything in your browser with nothing sent anywhere.

How the answers are generated

The AI is instructed to answer only from what's directly in your document, and to say so plainly if the answer isn't there rather than guess. That said, it doesn't cite page numbers or highlight the exact passage it used — the tool is a starting point, not a replacement for reading the document yourself. It can save you hours of scrolling, but if the document is critical, you should still confirm the details against the original.

Think of it as a knowledgeable assistant who has read the document once and remembers the gist of it. They can point you in the right direction, but they might occasionally misremember something, and they won't tell you exactly which page to check — that part's on you.

This tool works from the PDF's existing text layer — it doesn't perform OCR itself. If your PDF is a scanned image with no selectable text, run it through OCR PDF first, then use the resulting text.

常见问题

“与 PDF 对话”适用于扫描版 PDF 吗？

仅当 PDF 已含有可选中文本时才可以。此工具本身不执行 OCR——对于纯图片扫描件，请先运行 OCR PDF，再使用提取出的文本。

我与 PDF 对话时，我的 PDF 数据是私密的吗？

Your original PDF is never uploaded — it's opened and its text extracted locally in your browser. That extracted text, along with your question, is then sent to PDFly's server, which forwards it to Google's Gemini API to generate an answer.

How accurate are the answers?

The AI is instructed to answer only from what's in your document and say so if it can't find the answer, but AI-generated answers can still contain errors and the tool doesn't cite page numbers. For anything important, check the answer against the original PDF.

文档或问题长度有限制吗？

提取出的文档文本上限为 40,000 个字符（约 10,000 个 token），每个问题上限为 2,000 个字符。