Explainpaper vs PDF.chat

Explainpaper is a web-based AI reader for research papers. Readers highlight confusing passages to get explanations with adjustable complexity, support for more than 50 languages, and context from the full paper. Paper chat answers questions using the paper’s content, allows follow-ups, and can summarize findings; answers can cite sections so readers can locate relevant material. The product also generates outlines, extracts key points, and shows relationships between concepts. Its free plan is available indefinitely and includes unlimited highlight explanations, follow-up questions, Zotero library import, and basic AI models. Pro costs $16 a month and adds Math Explain for formulas and figures, advanced AI models, whole-paper summaries, saved highlights and explanations, and paper questions. The Pro trial lasts seven days and requires a card. Explainpaper says subscriptions are billed monthly or annually according to the selected plan and payments are processed through Stripe. The product describes its audience as researchers.

PDF.chat lets users upload documents, ask questions, and receive answers cited to exact pages in over 100 languages. It accepts PDFs, Word and PowerPoint files, text files, and images, including scanned or photographed documents that its OCR models read on its own infrastructure. Long documents are indexed so questions can retrieve relevant pages from reports, textbooks, and dockets. Users can compare Claude, GPT, Gemini, Llama, and DeepSeek answers side by side in one chat, then export results as plain text, Markdown, DOCX, searchable PDF, CSV, or JSON. The service runs in a browser without a download or installation. Its REST API ingests documents, returns per-page text and metadata, and supports chat with page citations; API use is metered per page. The Free plan costs nothing, with pages resetting at midnight UTC and no credit card required. Starter costs $5 a month and includes 750 pages per month. PDF.chat says files are automatically deleted shortly after processing and are not sold, shared, or used for training; on paid tiers, relevant passages may be sent to third-party AI providers.