Overview Sider is a browser extension AI assistant that layers a sidebar chat interface over every webpage you visit — read a page and ask questions about it, translate a passage, summarize an article, rewrite an email, generate an image, or query the underlying frontier models directly without leaving the tab you are already on. Launched in 2023 as a ChatGPT wrapper extension and iterated aggressively through the AI assistant boom of 2024 2026, Sider (rebranded from "Sider ChatGPT Sidebar") has grown into one of the most installed browser AI extensions on the Chrome Web Store — over 5 million users by 2026 — and a legitimately useful daily driver tool for a specific buyer. Sider's positioning matters because the browser AI category has diverged into three lanes. First: browser integrated AI baked directly into a specific browser (Brave Leo, Arc AI, Edge Copilot) — these require you to switch browsers. Second: standalone AI assistants used through separate tabs or apps (ChatGPT, Perplexity) — these require constant context switching. Third: browser extension AI assistants that layer over your existing browser (Sider, Merlin AI, MaxAI) — these give you the always available sidebar without asking you to switch browsers. Sider is the most installed and most feature complete of the extension tier. The one line positioning: Sider is the tool you use when you want a ChatGPT style AI sidebar available in every browser tab on Chrome, Edge, Safari, or Firefox — without switching browsers to Brave or Arc, and without…