21st Agents SDK

SDK launched by 21st.dev (March 2026) to deploy production agents with native UI, persistent memory and built-in observability. Beyond component copy-paste: you build a UI-aware agent (pre-wired 21st.dev components), ship with memory + traces, and monitor in prod. Competing approach to Vercel AI SDK + Mastra on the UI side.

Strengths

Limitations

Best for

Official site

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