Onhand: Chat with PDFs, Answers Highlighted — ramaway

Onhand is a free, open-source AI reading assistant for Firefox. Ask a question about the webpage, PDF or research paper you're reading, and Onhand highlights the passage that answers it, leaves a note in the margin, and explains it in the sidebar. You check the answer against the source instead of trusting a chat transcript.

Free to try: no API key, no account. Choose Onhand Free in the sidebar and start asking, with a daily limit. For more, sign in with your ChatGPT plan or use your own OpenAI, Anthropic, Google Gemini or OpenRouter key.

• Chat with any webpage or PDF and see the source, highlighted on the page with a note beside it.
• A built-in PDF viewer for papers, textbooks and long documents. For a PDF on your computer, choose or drop the file into the viewer.
• Follows citations: ask what a reference like [14] says, and Onhand opens the cited paper and answers from it.
• Compares sources across clearly related open tabs, highlighting each claim where it came from.
• Learning mode asks guiding questions and quizzes you as you read, instead of handing over answers.
• Study sessions stay in your browser, so you can reopen a paper and pick up where you left off.

Onhand starts with the active page and may read clearly related open tabs; relevant page content goes to the AI provider you choose (through Onhand's hosted service for Onhand Free). Anonymous diagnostics are sent only if you allow technical data in Firefox.

Source code: https://github.com/Phineas1500/Onhand