21st

21st

21st.dev
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About

21st is a developer platform that provides the fastest way to add AI agents directly into applications. The platform offers an SDK that allows developers to define, deploy, and run AI agents with minimal infrastructure setup. Developers can integrate agents using popular frameworks such as Next.js, React, TypeScript, Python, and Node.js. 21st includes built-in features like chat interfaces, session history, tool execution, memory, and real-time streaming responses. The platform also manages backend components such as sandboxed execution environments, authentication, rate limits, and observability. With support for Claude Code and Codex runtimes, developers can build agents that interact with tools, files, and APIs securely. By handling infrastructure and deployment automatically, 21st enables teams to launch production-ready AI agents quickly.

About

Flue is an open agent framework for building durable AI agents with a programmable TypeScript harness. Created by the team behind Astro, it uses a React-like hooks API to compose agent behavior, persistent state, lifecycle events, models, tools, sandboxes, subagents, skills, and MCP servers in code. Agents are stateful and addressable over HTTP, keep context across conversations and events, and can change capabilities as work progresses. Flue records every session in a durable stream, so accepted work survives crashes, restarts, and deploys; interrupted sessions resume automatically and clients reconnect without starting over. Developers can run agents locally, in CI, from their own backend, or orchestrate them with systems such as Cloudflare Workflows and Inngest. Secure sandboxes let agents run commands, edit files, and do real work, while tools connect them to APIs and data. Flue is powered by Pi and supports different LLM providers, allowing teams to choose the models they want.

Platforms Supported

Windows Not Supported
Mac Not Supported
Linux Not Supported
Cloud Supported
On-Premises Not Supported
iPhone Not Supported
iPad Not Supported
Android Not Supported
Chromebook Not Supported

Platforms Supported

Windows Not Supported
Mac Not Supported
Linux Not Supported
Cloud Supported
On-Premises Not Supported
iPhone Not Supported
iPad Not Supported
Android Not Supported
Chromebook Not Supported

Audience

Software developers, startups, and product teams that want a fast and scalable way to build and deploy AI agents inside their applications

Audience

Developers and AI engineering teams requiring a tool to build durable, stateful agents that can use tools, maintain context, and run across different models and deployment environments

Support

Phone Support Not Supported
24/7 Live Support Not Supported
Online Supported

Support

Phone Support Not Supported
24/7 Live Support Not Supported
Online Supported

API

Offers API Not Supported

API

Offers API Supported

Screenshots and Videos

Screenshots and Videos

Pricing

Free
Free Version Supported
Free Trial Not Supported

Pricing

No information available.
Free Version Not Supported
Free Trial Not Supported

Reviews/Ratings

Overall 0.0 / 5
ease 0.0 / 5
features 0.0 / 5
design 0.0 / 5
support 0.0 / 5

This software hasn't been reviewed yet. Be the first to provide a review:

Review this Software

Reviews/Ratings

Overall 0.0 / 5
ease 0.0 / 5
features 0.0 / 5
design 0.0 / 5
support 0.0 / 5

This software hasn't been reviewed yet. Be the first to provide a review:

Review this Software

Training

Documentation Supported
Webinars Not Supported
Live Online Not Supported
In Person Not Supported

Training

Documentation Supported
Webinars Not Supported
Live Online Not Supported
In Person Not Supported

Company Information

21st.dev
21st.dev/

Company Information

Flue
Founded: 2026
United States
flueframework.com

Alternatives

Alternatives

eve

eve

Vercel
StateFabric

StateFabric

J Gregory Technology Ltd.

Categories

AI SDKs Supported
UI Design Supported

Categories

Agentic AI Supported

Integrations

Braintrust Not Supported
Cloudflare Not Supported
Discord Not Supported
E2B Not Supported
Google Chat Not Supported
Linear Not Supported
Microsoft Teams Not Supported
Model Context Protocol (MCP) Not Supported
MySQL Not Supported
Notion Not Supported
OpenClaw Not Supported
React Supported
Resend Not Supported
Salesforce Not Supported
Slack Not Supported
Supabase Not Supported
Twilio Not Supported
Vercel Not Supported
WhatsApp Not Supported
shadcn/ui Supported

Integrations

Braintrust Supported
Cloudflare Supported
Discord Supported
E2B Supported
Google Chat Supported
Linear Supported
Microsoft Teams Supported
Model Context Protocol (MCP) Supported
MySQL Supported
Notion Supported
OpenClaw Supported
React Not Supported
Resend Supported
Salesforce Supported
Slack Supported
Supabase Supported
Twilio Supported
Vercel Supported
WhatsApp Supported
shadcn/ui Not Supported
Claim 21st and update features and information
Claim 21st and update features and information
Claim Flue and update features and information
Claim Flue and update features and information