The 21st Agents SDK is a comprehensive development toolkit for rapidly building and deploying AI agents. It provides built-in UI components, chat history management, spend limits, isolated sandbox execution, and full observability. It seamlessly integrates with leading AI models like Claude and OpenAI, enabling developers to create sophisticated, production-ready AI applications with minimal setup.
Freemium
How to use 21st Agents SDK?
Integrate the SDK into your Next.js, Python, or other applications to add AI agent capabilities. Use the pre-built UI components for chat interfaces, manage agent sessions with built-in history, and execute code safely in isolated sandboxes. Set token limits and spending caps for cost control. The SDK handles streaming responses, authentication, and provides session replay for debugging, allowing you to focus on building agent logic rather than infrastructure.
21st Agents SDK 's Core Features
Built-in UI Components: Accelerate development with ready-to-use, customizable UI elements for chat interfaces, inputs, and agent interactions, reducing frontend work.
Sandbox Execution & Security: Run agent code in isolated, per-session virtual machines (E2B Sandboxes) for safe execution, preventing system access and ensuring security.
Comprehensive Observability: Gain insights with session replay, detailed execution traces, and monitoring tools to debug, analyze, and improve agent performance and behavior.
Flexible AI Model Integration: Works seamlessly with major AI providers like OpenAI and Anthropic's Claude, allowing you to choose and switch between models based on your needs.
Managed Infrastructure: The SDK handles complex backend needs including streaming (SSE), authentication, rate limiting, spend caps, and persistent chat history out of the box.
Agent Templates & Examples: Jumpstart projects with production-ready templates for common use cases like chat apps, email copilots, web scrapers, and monitoring agents.
21st Agents SDK 's Use Cases
Developers building AI-powered chat applications can rapidly prototype and deploy using pre-built UI and backend, saving weeks of development time.
Product teams creating internal copilots for tasks like email management or data entry can leverage secure sandboxing and pre-built agent templates.
Startups needing to add AI features to their SaaS product can integrate intelligent agents for customer support, onboarding, or automation without building from scratch.
Enterprises implementing AI for workflow automation can use the SDK's spend limits and observability to safely pilot and scale agent deployments across teams.
Indie hackers and solo founders can build and ship AI-powered tools quickly by focusing on their unique agent logic while the SDK handles the complex infrastructure.
