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

Sandbox0 is an Apache-2.0 sandbox runtime for long-running AI agents and services that execute untrusted code. It provides isolated Linux environments with command execution, stateful contexts, file operations, SSH, supervised sessions, and network controls. Sandboxes retain a durable writable RootFS across successful pause-and-resume checkpoints; snapshots, restore, and forks support reusable workspaces. The Python, JavaScript/TypeScript, and Go SDKs, HTTP API, and s0 CLI let applications create and manage sandboxes. Sandbox0 Cloud provides hosted access, while teams can self-host the runtime on dedicated Nomad infrastructure. Default pause preserves filesystem state, not live process memory or external connections; experimental memory recovery requires compatible deployment support.

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 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 building long-running AI agents, coding-agent platforms, isolated code execution services and persistent developer workspaces.

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 Not Supported

API

Offers API Not Supported

API

Offers API Supported

Screenshots and Videos

Screenshots and Videos

No images available

Pricing

Free
Free Version Supported
Free Trial Not Supported

Pricing

$0.015/GiB-hour
Free Version 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 Not Supported
Webinars Not Supported
Live Online Not Supported
In Person Not Supported

Company Information

21st.dev
21st.dev/

Company Information

Sandbox0
sandbox0.ai/

Alternatives

Alternatives

Sprites

Sprites

Fly.io

Categories

AI SDKs Supported
UI Design Supported

Categories

Sandbox Supported

Integrations

React Supported
Tailwind CSS Supported
shadcn/ui Supported

Integrations

React Not Supported
Tailwind CSS Not Supported
shadcn/ui Not Supported
Claim 21st and update features and information
Claim 21st and update features and information
Claim Sandbox0 and update features and information
Claim Sandbox0 and update features and information