Sider AI vs CastReader: Which is Better in 2026?
We've compared 2 tools across pricing, features, ratings, and reviews to help you make an informed decision. No paid placements — just facts.
Compare different tools →| Feature |  Sider AI Browser Extensions |  CastReader Browser Extensions |
|---|---|---|
| Rating | No reviews yet | No reviews yet |
| Pricing |
as of Nov 7, 2026 |
as of Oct 23, 2026 |
| Pricing Model | Freemium | Freemium |
| Free Plan | ||
| Free Trial | ||
| API Available | ||
| Verified | ||
| Founded | 2023 | — |
| HQ | Medford, Massachusetts, USA | — |
| Team Size | 51-200 employees | — |
| Platforms | — | ChromeEdgeFirefoxSafari+4 more |
| Top Integrations | ChromeEdgeGmailChatGPT (GPTs & plugins)+4 more | — |
| Key Features |
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| Description | Sider is a browser-extension AI assistant that overlays a sidebar on any website—Gmail, Google Docs, YouTube, PDFs, news, and social sites—so you can chat, summarize, translate, write, and research without switching tabs. It aggregates 20+ models (OpenAI GPT, Anthropic Claude, Google Gemini, DeepSeek, and xAI Grok) behind one subscription, aimed at students, freelancers, marketers, and knowledge workers who juggle reading, writing, and translation across the web. Its main differentiator is being an always-available in-page sidebar bundling many premium models plus a citing Deep Research agent, rather than a single-model standalone chatbot. | CastReader is a text-to-speech reader available as browser extensions and mobile and desktop apps. It reads webpages, PDFs, Kindle books and AI chatbot answers aloud with synced highlighting. |