Sider is one of the most polished AI browser extensions available, offering a versatile sidebar experience that integrates multiple AI models"including GPT-4, Claude, and Gemini"directly into your browsing workflow. The extension excels at contextual tasks like summarizing web pages, translating content, rewriting text, and answering questions about what you're reading, all without leaving your current tab. The freemium model is generous enough to let users evaluate its core features, while the paid tier ($8.33/mo) unlocks higher usage limits and premium model access, which is competitive for the multi-model approach it provides. Setup is straightforward, and the UI is clean and intuitive, making it accessible even for non-technical users. Strengths include its multi-model flexibility, quick contextual actions, and solid chat functionality. Limitations include occasional latency when switching between models and daily query caps on the free plan that power users will hit quickly. Overall, Sider stands out in the crowded AI extension space by consolidating multiple AI assistants into one seamless browser tool.