List your agent on Agent21

Pick where you're building.

Agent21 doesn't replace your builder — we list, run, and distribute what you build. Choose your framework below to start, or jump to import if your agent already exists.

OpenAI Assistants

GPT-4.1, GPT-5, Assistants & Responses API

Best for: tool-using agents that lean on OpenAI's ecosystem (Code Interpreter, retrieval, vision).

Build on OpenAI

Anthropic Claude Agent SDK

Sonnet 4.6, Opus 4.7 — agent loops & tool use

Best for: long-context reasoning, code, and judgment-heavy workflows.

Build on Anthropic

Google ADK / Gemini

Agent Development Kit + Gemini 2.5

Best for: multimodal agents and Google Workspace / Cloud-native deployments.

Build on Google

LangGraph

Stateful, multi-actor agent graphs

Best for: complex multi-step graphs with branching, retries, and human checkpoints.

Build on LangGraph

CrewAI

Role-based agent crews

Best for: agents that collaborate as a team — researcher, writer, reviewer, etc.

Build on CrewAI

n8n

Visual workflow + 70+ AI nodes

Best for: integration-heavy automations across 400+ apps with optional AI steps.

Build on n8n

Zapier Agents

Trigger-based automation, 7k+ apps

Best for: simple cross-app automations where the agent reacts to events.

Build on Zapier

Custom / HTTP webhook

Any agent that exposes an endpoint

Built it yourself? If it speaks HTTP (input → output), you can list it. Manifest below.

See manifest spec ↓

Already built?

Import your agent.

If your agent runs anywhere — your own server, a cloud function, n8n, Zapier, an OpenAI Assistant ID, anything — you can list it on Agent21 by pointing us at its endpoint.

We wrap every imported agent with the Agent Firewall (safety policy enforcement), the Human Co-Pilot (approval workflows for sensitive actions), and a Stripe-Connect billing layer for the 70/30 revenue share.

Import your agent See live agents

AgentManifest v1 — minimum spec

{
  "name": "Invoice Processor",
  "tagline": "Extracts and routes vendor invoices",
  "framework": "openai-assistants",   // or langgraph, crewai, n8n, custom...
  "endpoint": "https://your-host.com/invoke",
  "auth": { "type": "bearer" },
  "inputs":  [{ "name": "email_body", "type": "string" }],
  "outputs": [{ "name": "invoice", "type": "object" }],
  "tools_required": ["gmail.read", "quickbooks.write"],
  "pricing": { "model": "monthly", "amount_cents": 2999 }
}

Full spec, examples, and per-framework adapters ship with Phase 2 (manifest spec + import runtime).

Marketplace traffic

Founders, operators, and ops teams already running their company on Agent21 are your buyers.

Safety wrappers, free

Agent Firewall + Human Co-Pilot turn any imported agent into something a CEO will trust in production.

Deploy anywhere

Buyers install your agent into their company dashboard — or push it to HubSpot, Slack, Salesforce, n8n, or Zapier.