Spec Driven Development
MCP Server that facilitates spec-driven development workflows, not just Vibe Coding.
Runs on your computer
MCP X402 Accept
Overview
Description from the maker (original English)
Self-hosted MCP proxy that puts an x402 paywall in front of an existing MCP server
PopNx MCP’s three pillars
These three are never merged into one score: opinions, measurements and popularity are different things.
- User voiceiNo reviews yetReviews open together with accounts in a later step
- Our basic checksi1 of 1 passedChecked from public information; code not scanned yet
- UsageiVery new↓ 68/wk · ★ –
What you can do with it
We have not written a plain-language summary for this one yet. Below are the facts we read from the registry.
- Connection: Runs on your computer
- Transport: stdio
- Category: Other
Install
Pick the AI app you use, then copy the settings.
Before you install
- Basic checks: 1 of 1 passed
- Runs on your computer with your user’s permissions (files, network, apps).
- The registry lists no key to fill in.
You need
- npmNode.js installed (for the npx command)
Which app do you use?
Pick your app above. We remember it, so next time the button says “Install in …”.
Open Claude Desktop → Settings → Developer → Edit Config, and paste this into claude_desktop_config.json
{
"mcpServers": {
"x402-accept": {
"command": "npx",
"args": [
"-y",
"@cryptoapis-io/mcp-x402-accept"
]
}
}
}Run this in your terminal
claude mcp add x402-accept -- npx -y @cryptoapis-io/mcp-x402-acceptOr copy the settings yourself
Paste into .cursor/mcp.json in your project, or ~/.cursor/mcp.json
{
"mcpServers": {
"x402-accept": {
"command": "npx",
"args": [
"-y",
"@cryptoapis-io/mcp-x402-accept"
]
}
}
}Your browser asks to open the app, then the app shows the settings and asks you to confirm. Key values are left empty for you to fill in.
Or copy the settings yourself
Paste into .vscode/mcp.json in your project
{
"servers": {
"x402-accept": {
"type": "stdio",
"command": "npx",
"args": [
"-y",
"@cryptoapis-io/mcp-x402-accept"
]
}
}
}Your browser asks to open the app, then the app shows the settings and asks you to confirm. Key values are left empty for you to fill in.
This one runs on your computer, and ChatGPT can only connect to servers on the internet. Pick another app.
Your choice stays on this device in a cookie; no account needed.
These settings are generated from the maker’s registry entry. If the README says otherwise, follow the README.
What it can do
Runs on your computer; the tool list appears in your AI app after you install it.
Basic checksi
We check information anyone can see; we have not read the code. Checks that do not apply are left out of the count. · Checked Nov 9, 2026
- ✓ Pass
Maker matches the repo
The registry name was verified with the GitHub account CryptoAPIs-io, which owns the repo
- … Not checked yet
Still maintained
We have not read this repo from GitHub yet
- … Not checked yet
Has a licence
We have not read this repo from GitHub yet
- – Not applicable
Endpoint responds
This one runs on your computer; there is no internet endpoint
- – Not applicable
Sign-in with OAuth
Runs on your computer and uses local settings instead
- … Not checked yet
No hidden instructions in tool descriptions
Runs on your computer; we can only read tool lists from internet endpoints
Compared with others in Otheri
- More stars than 0% of the other 18676 servers in this category
- Published to the registry more recently than 17% of the other 18676 servers in this category
- Basic checks equal to or better than 100% of the other 18676 servers in this category
Compared with every active server in this category in the registry. Stars count only when the publisher owns the repo.
Common questions
Is MCP X402 Accept safe?
It passed 1 of 1 applicable basic checks. We have not read the code. Before adding a key or token, see what access the server asks for and use a key with only the permissions you need.
What keys or codes does it need?
The registry does not list a required key, though some servers ask you to sign in on first use.
Does it run on my computer or in the cloud?
It runs on your computer. Your AI app starts it when needed, and data does not pass through the maker’s servers (unless it calls an online service itself).
Is it still maintained?
The GitHub repo last changed –, and the latest version (0.1.1) reached the registry 3 months ago.
Which apps can use it?
Apps that support MCP, such as Claude Desktop, Claude Code, Cursor and VS Code. You also need Node.js on your computer.
What can I use instead?
In the same category: Spec Driven Development, Remote Desktop Commander, Mcphost
Alternatives
Servers in the same category from other makers, sorted by stars.
Reading a card:↓ Downloads per weeki★ GitHub starsiThree pillars: reviews · checks · usageiUpdated = latest version published to the registryi
Remote Desktop Commander
Remote Desktop Commander: use files, terminal and processes on your own computers from any AI app.
Runs in the cloud✓ desktopcommander.app
Mcphost
Hosted MCP runtime where your agent publishes its own tools by tool call and keeps working.
Runs in the cloud✓ mcphost.dev
README from the maker
Open the README
Copied from the maker’s repo as written. PopNx MCP has not reviewed or endorsed it. HTML, images and scripts are removed. Links lead off this site.
@cryptoapis-io/mcp-x402-accept
Put an x402 paywall in front of an MCP server you already run — charge AI agents per tool call without changing a line of that server's code.
agent → mcp-x402-accept (your process) → your existing MCP serverThe proxy is an MCP server to the agent and an MCP client to yours. It mirrors every tool your server exposes; the ones you price are paywalled, the rest pass through free.
When to use this (and when not to)
| Your situation | Use |
|---|---|
| You can edit your MCP server (Node/TS) | x402-merchant-sdk/mcp — three lines around your handler, nothing in the data path |
| You cannot — third-party, closed-source, or not Node | this proxy |
If you can edit your server, do that instead. It is simpler and strictly fewer moving parts. This package exists for the case where that is not an option.
Why self-hosted only
You run this process. We never do, and we do not offer a hosted version.
That is a deliberate product decision, not a default you can flip. A proxy sits between an agent and your server, so a hosted one would mean CryptoAPIs holding your upstream server's credentials, sitting in the cleartext path of your tool arguments and results, and owing you uptime on your own revenue. For a merchant whose product *is* the data flowing through those calls, that is not a reasonable thing to ask. Self-hosting removes the question rather than answering it.
What that guarantees, structurally:
- Tool arguments and results are opaque to the proxy. It reads the tool *name* (is this priced?) and
_meta["x402/payment"](is it paid for?) — nothing else. They are never parsed, logged, buffered, or cached. - Your upstream credentials are your own env vars, in your own process.
- The only outbound calls are to the CryptoAPIs facilitator, to
/verifyand/settlethe payment itself.
Install
npm install -g @cryptoapis-io/mcp-x402-acceptConfigure
{"upstream": { "transport": "stdio", "command": "node", "args": ["/path/to/your-mcp-server.js"], "env": { "YOUR_UPSTREAM_TOKEN": "${YOUR_UPSTREAM_TOKEN}" } },
"apiKey": "${CRYPTOAPIS_API_KEY}", "payTo": "0xYourReceivingAddress",
// Only these are charged for. Everything else your server exposes stays FREE. "pricedTools": { "premium_data": { "network": "eip155:8453", "asset": "0x833589fCD6eDb6E08f4c7C32D4f71b54bdA02913", "amount": "10000" } } }
${VAR} reads from the environment, so the config file itself holds no secrets and is safe to commit.
amount is in atomic units — USDC has 6 decimals, so "10000" is $0.01. Getting this wrong by 10^6 is the easiest mistake here.
An HTTP upstream instead of stdio:
"upstream": {"transport": "http", "url": "https://your-server.example.com/mcp", "headers": { "Authorization": "Bearer ${YOUR_UPSTREAM_TOKEN}" } }
To accept several assets or networks for one tool, pass an array — the agent picks one. Offer only what GET https://ai.cryptoapis.io/x402/merchant/supported lists (public, no key); anything else is advertised and then rejected at /verify.
Run
cryptoapis-mcp-x402-accept --config ./x402-accept.config.jsonThen point agents at the proxy instead of your server. In Claude Code:
claude mcp add my-paid-tools -- cryptoapis-mcp-x402-accept --config /abs/path/to/config.jsonEverything is validated at boot — the config, the upstream connection, and whether the tools you priced actually exist upstream. A typo'd tool name is a hard failure, not a silent revenue hole: the alternative is believing a tool is paywalled while it quietly serves for free.
What an agent sees
| Step | Result |
|---|---|
| Unpaid call to a priced tool | isError: true carrying PaymentRequired in both structuredContent and content[0].text |
| Agent pays | Signs locally, retries with the payload in _meta["x402/payment"] — raw JSON, no base64 |
| Paid call | Your tool's real result, with the receipt in _meta["x402/payment-response"] |
| Call to an unpriced tool | Forwarded, free, unchanged |
Your server is never called until payment has settled. The proxy charges and then forwards — it does not forward and then bill. An unpaid call cannot reach your server at all, so it cannot be made to do the work for free.
Priced tools advertise [paid: x402] in their description so an agent knows the cost *before* calling. An agent that discovers a price only by being refused has already wasted a round-trip.
Paying it
Agents pay with @cryptoapis-io/mcp-x402-pay or, in code, @cryptoapis-io/x402-buyer-sdk/mcp.
Notes
- Requires a CryptoAPIs API key with the `X402_FACILITATOR` feature.
"settle": falseverifies without settling — useful while wiring up, but advisory only: the buyer proved they *could* pay, not that they did. Never ship it.- Test end-to-end on Base Sepolia (
eip155:84532) before charging real money. - Implements the x402 v2 MCP transport (spec), sharing one implementation with the merchant SDK — a spec fix lands in both.