ChatPDF vs Otio

ChatPDF

• Students and researchers who want quick answers from a paper or textbook chapter
• Asking questions across several files kept in one folder
• Trying a document chat tool without creating an account
• Turning course material into flashcards or slides

Otio

• Researchers synthesizing dozens of papers into a literature review
• Consultants, lawyers and analysts working across many client documents
• People who want several AI models under one subscription
• Learning from videos and podcasts as well as PDFs

ChatPDF

• The website shows Plus prices only in an upgrade dialog and sets them per visitor; the prices here are US App Store in-app purchases, and web checkout may differ.
• The free plan covers 2 documents a day, and the site's limits cap free use at 20 messages a day and files of 120 pages or 10 MB.
• AI Research summaries are built from abstracts, and chatting with a full paper works only for open-access papers.
• The best model is reserved for Plus; ChatPDF says it routes queries between GPT-4o and GPT-4o-mini.

Otio

• The Free plan allows 10 uploads a day, 25 MB per file and 50 MB in total, with 1 space and 2 parallel chats.
• The site's FAQ puts daily Free usage at about 1 to 2 deep searches, 10 premium-model chats or 50 standard chats.
• Lite costs the same on monthly and annual billing; the 50% annual saving applies to Go and Pro.
• The pricing page lists web, desktop and iPhone apps; no Android app is listed.

ChatPDF

Chat with documents

Ask questions about a PDF, Word, PowerPoint, Markdown or text file with the chat and the document side by side. Clickable citations scroll to the passage an answer came from.

Multi-file folders

Put files in a folder to ask questions across all of them in one conversation. Folders and saved chat history need a free account.

AI Research

Ask a question to find academic papers and get a summary with citations, built from the papers' abstracts. Filters narrow results to recent or influential work.

YouTube and website chat

Paste a YouTube or website link to ask questions about it. Video answers include clickable timestamps and an interactive transcript.

Flashcards, slides and writing

Makes flashcards that export to Anki, Quizlet, Brainscape or CSV, and slides that export to PowerPoint. The AI Writer drafts text with citations and exports to Word or Markdown.

Developer API

A backend API adds PDFs by URL or file upload and answers questions about them, with optional page references. API files are limited to 2,000 pages or 32 MB.

Otio

Chat across your sources

Ask one question across everything in a workspace and get an answer cited to the exact page or timestamp. Sources include PDFs, web pages, YouTube videos, podcasts, audio and spreadsheets.

Many AI models on every plan

ChatGPT, Claude, Gemini, Grok, Llama, DeepSeek and Moonshot models are available on all plans, with an Auto router and a side-by-side comparison of two models.

Deep Research

Multi-step research across your own sources and the open web, with each step of the reasoning visible. It is included on the Free plan within its usage limits.

Reader and notes

A reader view lets you highlight a passage in a source and ask about it. Notes made from a PDF or video are editable and export as Markdown.

Spaces

Separate workspaces keep each project's sources, chats and outputs apart: 1 on Free, 2 on Lite and 5 on Go.

Outputs and delivery

Generates documents, charts from spreadsheets and images, and can deliver results by email, Google Drive or Telegram.

ChatPDF

• Free$0

  2 documents and 20 messages a day, with files of up to 120 pages or 10 MB and folders of up to 5 files.

• Plus$14.99

  per month on the US App Store; $89.99 for the yearly plan

  Unlimited questions and documents, files of up to 2,000 pages or 150 MB, 50 PDFs per folder and the higher-quality model.

Otio

• Free$0

  Limited AI usage with every model and Deep Research, 10 uploads a day, 50 MB of storage, 1 space and 2 parallel chats.

• Lite$7

  per month, billed monthly; or $84 billed annually

  50 uploads a day, PDFs of up to 500 pages, 250 MB of storage, 2 spaces and 5 parallel chats.

• Go$18

  per month, billed annually ($216); $36 billed monthly

  3 times the chats, research and uploads of Lite: 250 uploads a day, 500 MB, PDFs of up to 1,000 pages, 5 spaces and 10 parallel chats.

• Pro$45

  per month, billed annually ($540); $90 billed monthly

  10 times the chats, research and uploads of Lite: 500 uploads a day, 1 GB of storage and PDFs of up to 2,000 pages.

• Team$25

  per seat / month, billed yearly; $30 billed monthly

  Everything in Pro with a shared workspace, central billing and user management, admin controls and priority support. Arranged through sales.

ChatPDF

• Annual discount

  About 50% off with the yearly plan

  On the US App Store the yearly Plus plan is $89.99 against $14.99 a month. That works out to about $7.50 a month, half the monthly rate.

Otio

• Annual discount

  Yearly billing halves the price of Go and Pro

  Go is $18 a month billed annually against $36 billed monthly, and Pro is $45 against $90. The pricing page labels yearly billing as saving 50%.