402sentinel MCP runs on your own machine — the client starts it, so there is no endpoint to ping. 125 installs a week from npm. Last commit 19 Oct 2026.
DEPRECATED: hosted 402Sentinel retired 2026-10-31. Client for x402 payment-safety checks.
Nothing serious here today
Today is the operative word: we check 402sentinel MCP every 15 minutes and re-read its code on every release. Watch it and you find out the day that stops being true.
Connect this server
This server runs on your own machine — install it with the package manager and the client starts it for you. Package name taken from the official registry entry.
claude mcp add 402sentinel-mcp -e 'CLIENT_PRIVATE_KEY=<CLIENT_PRIVATE_KEY>' -e 'SENTINEL_URL=<SENTINEL_URL>' -- npx -y @kaditang/402sentinel-mcp{
"mcpServers": {
"402sentinel-mcp": {
"command": "npx",
"args": [
"-y",
"@kaditang/402sentinel-mcp"
],
"env": {
"CLIENT_PRIVATE_KEY": "<CLIENT_PRIVATE_KEY>",
"SENTINEL_URL": "<SENTINEL_URL>"
}
}
}
}[mcp_servers.402sentinel-mcp]
command = "npx"
args = ["-y", "@kaditang/402sentinel-mcp"]
env = { CLIENT_PRIVATE_KEY = "<CLIENT_PRIVATE_KEY>", SENTINEL_URL = "<SENTINEL_URL>" }{
"mcpServers": {
"402sentinel-mcp": {
"command": "npx",
"args": [
"-y",
"@kaditang/402sentinel-mcp"
],
"env": {
"CLIENT_PRIVATE_KEY": "<CLIENT_PRIVATE_KEY>",
"SENTINEL_URL": "<SENTINEL_URL>"
}
}
}
}{
"servers": {
"402sentinel-mcp": {
"type": "stdio",
"command": "npx",
"args": [
"-y",
"@kaditang/402sentinel-mcp"
],
"env": {
"CLIENT_PRIVATE_KEY": "<CLIENT_PRIVATE_KEY>",
"SENTINEL_URL": "<SENTINEL_URL>"
}
}
}
}Put your own values in place of
<CLIENT_PRIVATE_KEY> (A Base wallet holding USDC on-chain (no gas needed) — pays per call, from $0.002), <SENTINEL_URL> (Required since 0.9.0 (the hosted service was retired on 2026-10-31): base URL of a 402Sentinel server you trust. 402sentinel.com is refused).
The author’s registry entry marks them as required.
Alternatives to 402sentinel MCP
same job, measured the same wayPre-payment safety gate for x402 agents: PII screening, spend policy, replay checks before signing.
Retired 2026-10-10. Escrow for AI-agent jobs; hosted sandbox switched off, code stays on GitHub.
x402 payment safety checks: validate a 402 answer, prove a server never serves before settlement.
Hosted x402 preflight for action authority, payment mandate, destination, expiry and replay.
MCP server for no-payment x402 surface triage, 402 Index health checks, and paid review handoff.
Pre-payment merchant trust checks for x402 agents on Base and Solana.
Pay less for x402 APIs: free pre-payment checks, cheapest working service finder, web/PDF reader.
Identity/reputation verification for agent-to-agent payments across x402, AP2, MPP, checkout.
402sentinel MCP — questions
Answers built from our own checks of this server.