Merlin

Merlin positions itself as a Swiss Army knife for AI chat, bundling access to ChatGPT, Claude, Gemini, Grok, and several other models into a single browser extension and mobile app. The core idea is simple: instead of paying for three or four separate AI subscriptions, you pay one $19/month fee and pick whichever model suits the task. In practice, this works well. The Chrome extension feels snappy — I could highlight text on a webpage and get a summary in seconds, or open a side panel to ask follow-up questions without leaving the page.

The tool's main differentiator is the breadth of models. The free tier is too restrictive for daily use (10 messages per day on most models), but the Pro plan unlocks generous caps: 5,000 messages per month on GPT-5.2, 1,000 on Claude Sonnet 4.6, and 500 on Claude Opus 4.6. That's more than enough for most casual and professional tasks. The Projects feature, which lets you upload PDFs and create reusable knowledge bases, is genuinely useful for research-heavy workflows. The diagram generator (Crafts) and code snippet tool are nice bonuses, though they feel like secondary features rather than core selling points.

The biggest drawback is the lack of a standalone desktop app — it's Chrome or mobile only, which limits its appeal for Firefox or Safari users. The message caps on the most powerful models (Claude Opus at 500/month) could frustrate power users. Still, for $19/month, Merlin undercuts most competitors while offering more model variety. It's a practical choice for anyone who wants flexibility without committing to a single AI ecosystem.