# Openbouncer > A reverse-captcha gateway and public registry for the agentic web. Cloudflare for agents — let verified agents in, politely deny humans. - **Type:** MCP server - **Install:** `agentstack add mcp-openbouncer-openbouncer` - **Verified:** Yes — security-reviewed for prompt injection and unsafe behavior - **Seller:** [OpenBouncer](https://agentstack.voostack.com/s/openbouncer) - **Installs:** 0 - **Category:** [Cloud & Infrastructure](https://agentstack.voostack.com/c/cloud-infrastructure) - **Latest version:** 0.1.0 - **License:** MIT - **Upstream author:** [OpenBouncer](https://github.com/OpenBouncer) - **Source:** https://github.com/OpenBouncer/openbouncer - **Website:** https://openbouncer.com ## Install ```sh agentstack add mcp-openbouncer-openbouncer ``` Requires the [AgentStack CLI](https://agentstack.voostack.com/docs/cli). Works with Claude Code, Cursor, and any MCP-compatible agent. ## About # OpenBouncer **A reverse-captcha gateway for the agentic web.** [](https://www.npmjs.com/package/@openbouncer/gate) [](./LICENSE) [](https://openbouncer.com) [](https://pump.fun/coin/4QyAdfEMBmPgMqtVy1gd6NthGsHzMctobUVEJqpwpump) Cloudflare protects sites from bots. OpenBouncer protects agent-only spaces from *humans* — and routes verified agents to the sites that want them. - Public preview live at **[openbouncer.com](https://openbouncer.com)** - npm: **[`@openbouncer/gate@preview`](https://www.npmjs.com/package/@openbouncer/gate)** - Community token `$OB` live on **[pump.fun](https://pump.fun/coin/4QyAdfEMBmPgMqtVy1gd6NthGsHzMctobUVEJqpwpump)** — creator rewards fund the build, holders unlock premium tiers ([see `#holders`](https://openbouncer.com/#holders)) - v0.1.draft · MIT licensed · built in the open --- ## What it is OpenBouncer is two things in one shape: 1. **A verification gateway** that sits in front of endpoints which only software should be calling. It exposes a single `POST /api/verify` that evaluates a layered set of proofs and returns `pass` or `deny` in under 40 ms. 2. **A public registry** that agents query as a discovery layer. Sites adopting OpenBouncer publish a `.well-known/openbouncer.json` document; agents read it to learn how to enter. Why? The agentic web (MCP, Computer Use, Operator, Gemini Agents) is shipping fast but there is no standard layer for *"this is an agent talking, not a human."* OpenBouncer plays the same network-effect game as Cloudflare did for bot defense — flipped. ## The layered protocol ``` L1 prompt-following challenge — agent extracted the page's hidden nonce L2 sub-200 ms latency window — request arrived faster than humans can L3 parallel reasoning proof — sub-second multi-task challenge (v0.2) L4 provider attestation — signed token from a recognized runtime (Anthropic, OpenAI, Google) ``` A request that matches **any** layer passes. The marketing site demo ships L1 and L4; L2/L3 land with the v0.2 spec. ## Try it from a terminal The public-preview gateway accepts a static demo nonce so anyone can curl-test the flow. ```sh # pass — agent payload curl -X POST https://openbouncer.com/api/verify \ -H 'Content-Type: application/json' \ -H 'X-Agent-Provider: anthropic' \ -d '{"nonce":"ob_demo_a8f3c9e2","attest":""}' # deny — browser-style bare click curl -X POST https://openbouncer.com/api/verify \ -H 'Content-Type: application/json' \ -d '{}' ``` Discovery: ```sh curl https://openbouncer.com/.well-known/openbouncer.json ``` Fresh per-session nonce for real integrations: ```sh curl https://openbouncer.com/api/challenge ``` ## Embed the gate on your site ```sh bun add @openbouncer/gate@preview # or: npm install @openbouncer/gate@preview ``` ```tsx import { OpenBouncerGate } from '@openbouncer/gate' export default function ProtectedPage({ nonce }: { nonce: string }) { return ( {/* rendered only for verified agents */} ) } ``` Three lines. Headless: zero CSS dependency, inline-styled defaults, ESM + CJS + `.d.ts`, ~24 KB unpacked. See [`packages/gate/README.md`](./packages/gate/README.md) for the full API reference. For non-React runtimes (Bun, Node, Workers, CLIs), import the pure async primitive: ```ts import { verify } from '@openbouncer/gate' const r = await verify({ nonce: 'ob_demo_a8f3c9e2', provider: 'anthropic', attest: '', }) // → { ok: true, decision: "pass", matched_layers: [1,4], token: "ob_..." } ``` ## Repo layout ``` . ├── server/ Fetch-API style handlers (Bun + Vite plugin) │ ├── index.ts standalone Bun server (production) │ └── lib/ │ ├── decision.ts layered evaluation (L1, L2, L3, L4) │ ├── verify.ts POST /api/verify │ ├── challenge.ts GET /api/challenge │ ├── well-known.ts GET /.well-known/openbouncer.json │ ├── router.ts tiny shared route table │ ├── rate-limit.ts in-memory per-IP token bucket │ ├── token.ts opaque pass-token envelope (v0.1) │ └── json.ts cors + security-header helper ├── src/ │ ├── components/ │ │ ├── OpenBouncerGate.tsx the widget — both 3rd-party gate + demo │ │ ├── Hero.tsx + the rest of the marketing site │ │ └── ... │ ├── App.tsx │ └── index.css ├── vite-plugin-openbouncer.ts dev plugin wiring the same handlers ├── vite.config.ts └── package.json ``` ## Development ```sh bun install bun run dev # vite + api on the same origin (http://localhost:5173) bun run server # bun-serve the api standalone (defaults to :3001) bun run typecheck # tsc -b bun run build # vite build ``` ## Deploy OpenBouncer ships as a single Cloudflare Pages project: the Vite-built static site under `dist/` plus a `functions/[[path]].ts` catchall that runs the same Fetch-API handlers used in dev and in the standalone Bun server. One origin, no CORS dance, edge-deployed globally. ```sh bunx wrangler login # one-time, opens browser bun run deploy # bun run build + wrangler pages deploy ``` `bun run deploy` is sugar for: ```sh wrangler pages deploy dist --project-name=openbouncer ``` To bind the custom domain (after the first deploy creates the project): ```sh bunx wrangler pages domain add openbouncer.com --project-name=openbouncer ``` Cloudflare provisions the SSL cert automatically once DNS is verified. Subsequent deploys push to the same project — set up the GitHub integration in the Cloudflare Pages dashboard for auto-deploy on push to `main`. ## Status (v0.1.draft) | Surface | State | | --- | --- | | Reverse-captcha widget | ✅ live on openbouncer.com | | `/api/verify` (L1 + L4 stub) | ✅ live | | `/api/challenge` (fresh nonce) | ✅ live | | `/.well-known/openbouncer.json` | ✅ live | | `@openbouncer/gate` npm package | ✅ published (preview tag) | | Per-session nonce store | ⏳ v0.2 | | Ed25519-signed pass tokens | ⏳ v0.2 | | Real provider-attestation verification | ⏳ v0.2 | | Stable `@openbouncer/gate` on the `latest` tag | ⏳ v0.2 | | Public registry UI | ⏳ v0.2 | | MCP server for agent discovery | ⏳ v0.2 | ## License [MIT](./LICENSE). ## Source & license This open-source MCP server is cataloged on AgentStack and links to its original source — we do not rehost the code. - **Author:** [OpenBouncer](https://github.com/OpenBouncer) - **Source:** [OpenBouncer/openbouncer](https://github.com/OpenBouncer/openbouncer) - **License:** MIT - **Homepage:** https://openbouncer.com Install and usage instructions live in the source repository linked above. ## Pricing - **Free** — Free ## Security capabilities Automated source analysis of v0.1.0 — what this tool can access: - **Network access:** yes - **Filesystem access:** no - **Shell / process execution:** no - **Environment & secrets:** no - **Dynamic code execution:** no *"Yes" means the capability is present in the source — more access means more to trust, not that it is unsafe.* ## Versions - **0.1.0** — security scan: passed — Imported from the upstream source. ## Links - Listing page: https://agentstack.voostack.com/l/mcp-openbouncer-openbouncer - Seller: https://agentstack.voostack.com/s/openbouncer - Browse the marketplace: https://agentstack.voostack.com/browse --- Listed on AgentStack — the marketplace for AI agent skills and MCP servers. Every listing is security-reviewed. Creators keep 70%.