Sider

Sider is a freemium AI-sidebar browser extension that brings a multi-model assistant into Chrome, Edge, Safari, and Firefox. It lets you highlight text to explain, translate, summarize, or rewrite, generates timestamped YouTube summaries, reads PDFs, and provides access to many leading models from one panel. It targets students, professionals, and everyday users who want productivity help without leaving the page they are on.

Sider (sider.ai) is one of the most popular AI-sidebar extensions, giving you instant access to a wide range of models, including options built on GPT, Claude, Gemini, and others, from a panel that opens on any webpage. Its signature workflow is highlight-to-act: select text and a popup lets you explain, translate, summarize, rewrite, or send it into a chat as context. It also produces timestamped YouTube summaries and can read and reason over PDFs. Built by a bootstrapped team, Sider has reached large scale on the Chrome Web Store with millions of downloads and a high review rating. It targets students, professionals, and everyday users who want an always-available assistant that boosts productivity while browsing, without committing to a single model provider. Sider competes with Monica, Merlin, and MaxAI. It leans on breadth of model choice, broad browser support (including Firefox and Safari alongside Chrome and Edge), and an approachable free tier. Because it is credit-limited on the free plan and its cheaper paid tiers, heavy users of premium models will want to compare limits carefully across competitors.