SatGate – Economic Firewall for AI Agents MCP Server

<p align="center"> <img src="docs/assets/logo.png" alt="SatGate" width="120" /> </p> <h1 align="center">SatGate</h1> <p align="center"> <strong>Observe, control and admit AI agent traffic</strong><br/> <em>Every allow or deny comes with a signed receipt</em> </p> <p align="center"> <a href="https://github.com/satgate-io/satgate/actions"><img src="https://github.com/satgate-io/satgate/workflows/CI/badge.svg" alt="CI Status"></a> <a href="https://goreportcard.com/report/github.com/satgate-io/satgate"><img src="https://goreportcard.com/badge/github.com/satgate-io/satgate" alt="Go Report Card"></a> <a href="https://pkg.go.dev/github.com/satgate-io/satgate"><img src="https://pkg.go.dev/badge/github.com/satgate-io/satgate.svg" alt="Go Reference"></a> <a href="LICENSE"><img src="https://img.shields.io/badge/License-Apache%202.0-blue.svg" alt="License"></a> </p> <p align="center"> <a href="#the-problem">Why</a> • <a href="#build-agents-with-satgate">Build</a> • <a href="#features">Features</a> • <a href="#quick-start">Quick Start</a> • <a href="#documentation">Docs</a> • <a href="https://satgate.io">Website</a> • <a href="https://satgate.io/blog/why-routing-isnt-governance">Blog</a> </p>

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SatGate is a gateway in front of APIs and MCP tools. It meters agent and MCP traffic (Observe), enforces owner budgets before work runs (Control), and charges external agents on the routes you choose (Admit; the Charge policy in the dashboard). Every allow or deny comes with a signed receipt.

Try it as an agent. This hosted route costs 10 sats or 0.01 USDC, and each payment buys one request:

curl -i https://mcp-prod-final.satgate.cloud/paid/premium

The unpaid call returns HTTP 402 with a Lightning invoice, a USDC-on-Base (x402) offer and the terms. Agent instructions are in llms.txt.

Build Agents with SatGate

SatGate's developer primitive is three calls: issue(), pay(), and verify().

import os
from satgate import SatGate

satgate = SatGate(api_key=os.getenv("SATGATE_API_KEY"))

capability = satgate.issue(
    task="research market prices",
    agent="research-agent",
    allow=["mcp:web.search", "api:prices.read"],
    budget_usd=25,
    expires_in="1h",
)

receipt = satgate.pay(
    upstream="https://api.example.com/search",
    capability=capability,
    max_usd=4.20,
)

verified = satgate.verify(receipt)
print(verified.decision, verified.evidence_pack_id)

Install today:

pip install satgate
npm install @satgate/sdk

The public packages install today; the issue/pay/verify API namespace is in private beta. Calls without private-beta access raise a structured error instead of returning fake receipts:

SatGateAuthError: This API namespace requires private beta access. Visit cloud.satgate.io/docs to request access.

Runnable examples:

• examples/python/issue_pay_verify.py
• examples/node/issue-pay-verify.mjs

Works with: MCP · OpenAI tools · Anthropic tools · LangChain · CrewAI · Raw HTTP

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<div align="center">

🎬 See SatGate in Action

<a href="https://satgate.io#explainer"><img src="https://img.shields.io/badge/▶_Explainer-30s-purple?style=for-the-badge" alt="Watch Explainer"></a>  <a href="https://satgate.io#delegation"><img src="https://img.shields.io/badge/▶_Token_Delegation-45s-blue?style=for-the-badge" alt="Watch Delegation"></a>

</div>

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<div align="center">

☁️ Don't want to self-host? Try SatGate Cloud

Managed SaaS — zero setup, multi-tenant isolation, enterprise dashboard.<br/> Free Observe tier. No credit card required.

<a href="https://cloud.satgate.io"><img src="https://img.shields.io/badge/🚀_Try_SatGate_Cloud-Free-blue?style=for-the-badge" alt="Try SatGate Cloud"></a>

</div>

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The Problem

AI agents are making API calls autonomously. They spawn sub-agents, call MCP tools, and run overnight while you sleep.

Your existing stack answers: "Is this request authenticated?"

Nobody answers: "Should this agent have authority to spend, delegate, or invoke this paid resource?"

✓ Network Firewall    → "Can this packet enter?"
✓ Application Firewall → "Is this request safe?"
? Economic Firewall    → "Should this agent act, spend, or pay?"

That's the gap. SatGate fills it.

What is SatGate?

SatGate is an Economic Firewall for AI agent requests. Drop it in front of your APIs and MCP tools to enforce scoped authority, budgets, paid-rail context, and Evidence Pack receipts before agents act.

Not another routing layer. Routing gateways (Bifrost, LiteLLM, Portkey) optimize which provider handles a call. SatGate governs whether the call should happen at all based on authority, policy, budget, and paid-rail context.

Use them together:

Agent → SatGate (economic governance) → Routing Gateway → LLM Providers

Features

• 🛡️ Capability Tokens (Macaroons) — Cryptographic credentials with built-in caveats, delegation, and next-request revocation. Not API keys — tokens that agents can safely sub-delegate.
• 🎯 MCP-Aware — Parses MCP JSON-RPC tool calls. Know that Agent X spent $47 on search_database and $12 on send_email — not just "1,000 requests."
• 💰 Budget Enforcement — Hard stops per agent, team, or API. When the budget hits zero, requests are blocked. Not logged. Not alerted. Blocked.
• ⚡ Paid-Rail Governance — Govern paid API access across L402, x402, API-key billing, and enterprise ledgers without making any one rail the control plane.
• 🔒 Default-Deny — All routes require valid credentials unless explicitly public. Zero Trust by design.
• 🚀 <50ms Overhead — Lightweight Go proxy. Adds governance without adding latency.
• 📦 Self-Hosted — Your infrastructure, your rules. Single binary, Docker, or Kubernetes.
• 🔌 Drop-in — Works with any HTTP backend. REST, GraphQL, MCP servers. No code changes.

Quick Start

60-Second Demo

# Download the binary (macOS Apple Silicon — see Releases for other platforms)
curl -L https://github.com/satgate-io/satgate/releases/latest/download/satgate-darwin-arm64 -o satgate
chmod +x satgate

# Start with example config (mock Lightning, auto-generated keys)
export ADMIN_TOKEN=my-secret-token
export LIGHTNING_BACKEND=mock
./satgate --config examples/gateway.yaml

Try the three policies:

# 1. Public — no auth needed
curl http://localhost:8080/health

# 2. Protected — mint a capability token, then use it
curl -X POST http://localhost:8080/api/capability/mint \
  -H "X-Admin-Token: my-secret-token" \
  -H "Content-Type: application/json" \
  -d '{"scope": "api:read", "duration": "1h"}'

# Use the token:
curl -H "Authorization: Bearer YOUR_CAPABILITY_TOKEN" \
  http://localhost:8080/api/capability/ping

# 3. Paid — get a payment challenge (L402 today; x402/other rails as governed context)
curl http://localhost:8080/api/micro

Public → Protected → Paid. Three policies, one gateway; paid rails are governed context, not the product boundary.

Hosted paid demo (Admit; Charge in the dashboard). No local Lightning node:

curl -i https://mcp-prod-final.satgate.cloud/paid/premium

Unpaid calls return 402. Price is 10 sats, or 0.01 USDC on Base, for one request. For Lightning, show the invoice to the owner, poll payment status, then retry. Poll rules and the USDC steps are in llms.txt.

📖 Full Quick Start Guide →

Other Install Methods

# Docker
docker run -v $(pwd)/gateway.yaml:/etc/satgate/gateway.yaml \
  -e ADMIN_TOKEN=my-secret-token -e LIGHTNING_BACKEND=mock \
  -p 8080:8080 ghcr.io/satgate-io/satgate:latest

# Build from source
git clone https://github.com/satgate-io/satgate.git
cd satgate && go build -o satgate ./cmd/satgate

Configuration

version: 1

server:
  listen: ":8080"

admin:
  capabilityRootKey: "${CAPABILITY_ROOT_KEY}"

lightning:
  provider: "${LIGHTNING_BACKEND}"
  config:
    connectionString: "${NWC_CONNECTION_STRING}"

upstreams:
  api:
    url: "http://localhost:3000"

routes:
  - name: public-health
    match:
      pathPrefix: /health
    upstream: api
    policy:
      kind: public

  - name: protected-api
    match:
      pathPrefix: /api/
    upstream: api
    policy:
      kind: capability
      scope: "api:read"

  - name: premium-api
    match:
      pathPrefix: /premium/
    upstream: api
    policy:
      kind: l402  # paid-rail policy; use payment_context to preserve L402/x402/ledger evidence
      priceSats: 100

Policy Types

Policy	Description	Use Case
public	No authentication	Health checks, docs, webhooks
capability	Requires valid Macaroon	Protected API endpoints
l402	Requires Lightning payment and records paid-rail context	Monetized endpoints; x402/ledger context can be preserved in Evidence Packs

How It's Different

	SatGate	Routing Gateways	Traditional API Gateways
Primary concern	Economic governance	Provider routing	Traffic management
Budget enforcement	Hard caps (blocked at limit)	Soft alerts only	❌
MCP cost attribution	Per-tool granularity	❌	❌
Credential model	Macaroons (delegatable)	API keys	API keys / OAuth
Agent delegation	Sub-tokens with reduced budgets	❌	❌
Paid-rail governance	L402, x402, API-key billing, enterprise ledgers	❌	❌
Works alongside	—	✅ Use together	✅ Use together

Architecture

┌──────────────────────────────────────────────────┐
│                    SatGate                        │
│                                                   │
│  Request → Route Match → Policy Check → Proxy    │
│                             │                     │
│              ┌──────────────┼──────────────┐     │
│              │              │              │      │
│          [public]    [capability]   [paid rail]  │
│          pass        verify token     verify     │
│                      check budget     payment    │
│                      log MCP tool     context    │
└──────────────────────────────────────────────────┘

Key Concepts:

• Macaroons: Bearer tokens with embedded caveats (expiry, scope, budget, IP). Not API keys — they support delegation without server roundtrips.
• Delegation: Agent A gives Agent B a sub-token with reduced permissions and a $50 budget cap. B can't escalate.
• MCP Parsing: SatGate reads MCP JSON-RPC payloads to attribute costs to specific tool calls, not just HTTP endpoints.
• Paid-rail context: SatGate treats L402, x402, API-key billing, and enterprise ledgers as rails to govern around. Evidence Packs preserve which rail was involved without making the rail the product.

SDKs

Language	Package	Docs
Python	pip install satgate	README
JavaScript	npm install @satgate/sdk	README

MCP Proxy (NEW)

SatGate now includes a native MCP proxy that governs tool calls for any MCP-compatible agent:

# Run MCP proxy with 1000-credit budget
satgate-mcp --config satgate-mcp.yaml

• Budget enforcement: Hard 402 when agents exhaust their allocation
• Delegation: Parent agents mint sub-agent tokens with carved budgets
• Per-tool costs: web_search: 5, dalle_generate: 50 (wildcard patterns supported)
• Two transports: stdio (local sidecar) or SSE/HTTP (remote multi-agent)
• Three auth modes: none, static token, macaroon (HMAC chain)

See pkg/mcpserver/README.md for full documentation.

Documentation

• Architecture Overview
• Quick Start Guide
• Configuration Reference
• Production Checklist
• Kubernetes Deployment
• LangChain Integration
• MCP Gateway Guide

☁️ SatGate Cloud & Enterprise

Self-hosting not your thing? SatGate Cloud is the fully managed version — same gateway, zero ops.

The open-source gateway handles protection, budgets, and paid-rail enforcement. SatGate Cloud adds the control plane:

• 📊 Observe — Real-time dashboards, usage attribution, cost center tagging
• 🎚️ Control — Budget and policy enforcement before agent requests execute
• 🤖 SatGate Mint — Zero-touch agent provisioning (K8s, AWS, OIDC)
• 🏢 Multi-tenant — Team isolation, RBAC, SSO/SCIM
• 📝 Audit — Tamper-evident logging, compliance exports

<a href="https://cloud.satgate.io"><strong>Start Free →</strong></a> (Observe mode is free, unlimited, forever)

Contributing

We welcome contributions! See CONTRIBUTING.md for guidelines.

git clone https://github.com/satgate-io/satgate.git
cd satgate
go mod download
go test ./...
go build -o satgate ./cmd/satgate

License

Apache License 2.0 — see LICENSE for details.

Links

• 🌐 satgate.io — Website
• 📝 Blog — Technical articles
• 🏢 Enterprise Governance — CISO/CFO/CTO use cases
• 💰 Pricing — Free Observe tier, Pro for enforcement
• 🔒 Security Model — Architecture & compliance
• 🧪 Sandbox — Try without signup
• 📊 ROI Calculator — Estimate savings
• ⚖️ Compare — SatGate vs Zuplo, Bifrost, cloud-native
• 📧 contact@satgate.io

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<p align="center"> _{Built with ⚡ by <a href="https://satgate.io">SatGate</a> — The Economic Firewall} </p>