Onhand

Onhand is a free AI reading assistant for Chrome. 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 side panel. Free to try: no API key, no account. Choose Onhand Free in the side panel and start asking, with a daily usage cap. For more, sign in with your ChatGPT plan or bring your own API key (OpenAI, Anthropic, Google Gemini, or any OpenRouter model). WHAT IT DOES — Chat with any PDF or webpage, and see the source. Every answer points at the passage that supports it, highlighted on the page with a note in the margin, so you can check it yourself instead of trusting a chat transcript. — Reads research papers properly. A built-in PDF viewer handles papers, textbooks and long documents, with the same highlights and notes as on webpages. — Chases citations. Ask "what does [14] actually say?" and Onhand finds the reference, opens the cited paper, and highlights the answer inside it. — Compares sources. Ask how the paper you're reading relates to another open tab, and each claim is highlighted in the source it came from. — Quizzes you while you study. Learning mode adds quick comprehension checks as you read and tracks the concepts you've covered, instead of just handing over answers. — Voice mode. Ask aloud while keeping your eyes on the page (uses an OpenAI API key). Study sessions are saved locally in your browser, so you can close a paper and pick the conversation back up later. WHO IT'S FOR Students, researchers and anyone reading something hard: journal articles and preprints, textbooks and lecture slides, documentation, long reports. Onhand explains the source in front of you instead of sending you to a chatbot in another tab. PRIVACY Onhand starts with the active page. To answer your request it may rank titles and URLs of eligible open tabs and read clearly related open tabs — in any mode, without switching your view; unrelated tabs are not read merely because they are open. In API-key and ChatGPT sign-in modes, relevant request and page content goes to your selected provider. In Onhand Free mode, request content goes through Onhand's hosted Cloudflare Worker to OpenAI's API; anonymous diagnostics are required for reliability, quota, cost, and abuse monitoring. Diagnostics and explicit error reports do not include prompts, page content, URLs, screenshots, transcripts, saved sessions, or keys. Open source (Apache 2.0): github.com/Phineas1500/Onhand Guides and comparisons: useonhand.com