LightPDF vs ChatPDF

LightPDF lets you upload PDFs, Word files, Excel spreadsheets, PowerPoint decks, and scanned documents, then ask questions and get cited answers back. The ChatPDF feature runs on GPT-4, supports multi-document chats, OCR for scanned files, and follow-up questions. You can upload a file up to 100 pages on the free web tier before upgrading.

Unlike standalone ChatPDF clones, LightPDF bundles document chat into a wider PDF toolkit with conversion, editing, e-signatures, and a dozen other AI tools like mind map creation, PDF translation, and presentation generation. One premium subscription covers Windows, Mac, Android, iOS, and the web app, with AI credits allocated monthly or as a one-time pool on the perpetual plan.

Researchers, students, and office workers use LightPDF to summarize contracts, extract tables from financial reports, and pull outlines from long readings. Business teams can also use it for document Q&A on proposals and compliance files. The company behind LightPDF has operated since 2015 and holds ISO/IEC 27001, ISO/IEC 27701, and GDPR certifications.

Upload a PDF and ask questions in plain language; ChatPDF maps every answer back to the page where it found the evidence. You can also paste YouTube links, website URLs, or plain text to start a chat without uploading a file. Supported uploads include PDF, Word, PowerPoint, Markdown, and plain text.

Unlike standalone PDF chat apps, ChatPDF bundles document chat with AI Research, AI Writer, AI Detector, YouTube chat, flashcards, and slides under one account. The side-by-side layout keeps your source open next to the chat, and citations jump straight to the referenced passage. General chatbots can summarize pasted text, but they do not map answers back to page numbers across multiple files in a folder.

Students use it to study for exams, summarize lecture notes, and work through homework faster. Researchers run literature reviews, chat with open-access papers in AI Research, and draft cite-ready text in AI Writer. Professionals turn to it for contracts, manuals, financial reports, and training materials.

The site cites more than 10 million users and over one million questions answered daily. ChatPDF routes queries between GPT-4o and GPT-4o-mini, and the free tier covers two documents per day with no account required.