facts402: x402 API finder + fact checks

Name: facts402: x402 API finder + fact checks
Author: veselin9931

by veselin9931version 0.1.1i★ –iRuns on your computer

Registry namecom.facts402/facts402-mcp

Install

Overview

Description from the maker (original English)

Find the right paid x402 API, plus fact checks: IBAN, EU VAT, OFAC sanctions, LEI, FX

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
UsageiNot measured yet★ –

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
You need to fill in: X402_PRIVATE_KEY

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).
You fill in yourself: X402_PRIVATE_KEY, X402_MAX_PER_CALL_USD, X402_SESSION_BUDGET_USD

Values marked secret are keys to your account. Never share them or paste them into a chat.

You need

PyPIPython’s uv installed (for the uvx command)

Which app do you use?

ClaudeClaude CodeCursorVS CodeChatGPT

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": {
    "facts402": {
      "command": "uvx",
      "args": [
        "facts402-mcp"
      ],
      "env": {
        "X402_PRIVATE_KEY": "your-value",
        "X402_MAX_PER_CALL_USD": "your-value",
        "X402_SESSION_BUDGET_USD": "your-value"
      }
    }
  }
}

Run this in your terminal

claude mcp add facts402 --env X402_PRIVATE_KEY=your-value --env X402_MAX_PER_CALL_USD=your-value --env X402_SESSION_BUDGET_USD=your-value -- uvx facts402-mcp

Fill in the empty values before running it.

Open in Cursor

Or copy the settings yourself

Paste into .cursor/mcp.json in your project, or ~/.cursor/mcp.json

{
  "mcpServers": {
    "facts402": {
      "command": "uvx",
      "args": [
        "facts402-mcp"
      ],
      "env": {
        "X402_PRIVATE_KEY": "your-value",
        "X402_MAX_PER_CALL_USD": "your-value",
        "X402_SESSION_BUDGET_USD": "your-value"
      }
    }
  }
}

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.

Open in VS Code

Or copy the settings yourself

Paste into .vscode/mcp.json in your project

{
  "servers": {
    "facts402": {
      "type": "stdio",
      "command": "uvx",
      "args": [
        "facts402-mcp"
      ],
      "env": {
        "X402_PRIVATE_KEY": "your-value",
        "X402_MAX_PER_CALL_USD": "your-value",
        "X402_SESSION_BUDGET_USD": "your-value"
      }
    }
  }
}

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.

Values you fill in

X402_PRIVATE_KEY secret env
Private key of your own Base mainnet wallet holding a little USDC. Optional: without it only the free tools work.
X402_MAX_PER_CALL_USD env
Most a single tool call may pay, in USD
X402_SESSION_BUDGET_USD env
Most the server may spend until it restarts, in USD

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 7, 2026

✓ Pass
Maker matches the repo
The registry name was verified against the domain facts402.com (the registry checks domain ownership)
… 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 32691 servers in this category
Published to the registry more recently than 86% of the other 32691 servers in this category
Basic checks equal to or better than 100% of the other 32691 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 facts402: x402 API finder + fact checks 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?

You need to fill in: X402_PRIVATE_KEY

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 5 days ago.

Which apps can use it?

Apps that support MCP, such as Claude Desktop, Claude Code, Cursor and VS Code. You also need Python (uv) on your computer.

What can I use instead?

In the same category: Spec Driven Development, Remote Desktop Commander, Dialyne

Alternatives

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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.

facts402-mcp

Find the right paid API for a task, and verified fact checks for AI agents. Before an agent pays an unknown API, x402_recommend ranks the x402 endpoints that fit the task by relevance, real on-chain buyers and liveness, for $0.005 (the preview is free). And at $0.01 per call: validate an IBAN before a payout. Check an EU VAT number in VIES before invoicing. Screen a name against OFAC sanctions. Look up a company's LEI. Validate a phone number or email before outreach. Convert currency at official ECB rates. Check how old a domain is. These are small, exact answers an agent can rely on, with no API keys or sign-up.

Pay per call with x402: USDC on Base, from your own wallet, within a per-call cap and a session budget you set.

Tools

Tool	Price (USDC)	Use it to
`x402_recommend`	$0.005	Find the best paid x402 endpoints for a task: url, price, network, 30-day buyers, liveness, risk flags, score
`x402_recommend_preview`	free	See the single top pick (host, price, buyers) for a task
`iban_check`	$0.01	Validate an IBAN and get bank name, BIC and SEPA membership
`eu_vat_check`	$0.01	Check an EU VAT number in VIES: status, company name and address
`sanctions_screen`	$0.01	Fuzzy-screen a person, company, vessel or aircraft against the OFAC SDN list
`lei_lookup`	$0.01	Look up a company in the GLEIF LEI index, by LEI or by name
`phone_check`	$0.01	Validate and normalise a phone number: E.164, line type, carrier, time zone
`email_check`	$0.01	Check email syntax, MX, disposable and role-account flags
`fx_convert`	$0.01	Convert currency at ECB reference rates, for the latest day or any of the last 90
`domain_check`	$0.01	Get a domain's age, registrar, status and DNSSEC via RDAP (WHOIS)
`business_days`	$0.01	Count business days and list public holidays between two dates
`weather_forecast`	$0.01	Get a forecast for any coordinates, up to 7 days
`sun_times`	$0.01	Get sunrise, sunset, golden hour and day length
`base_token_check`	$0.01	Get raw on-chain facts for a Base ERC-20 contract (owner, proxy, mint / pause / blacklist)

The service charges only for a successful (2xx) answer: invalid input, upstream errors and a recommend query with no match (404) are never charged. Recommendations use the x402-list.com catalog (CC BY 4.0) and sellers' own 402 quotes, filtered and re-scored by facts402; facts402's own APIs are ranked with the same formula. For Base memecoin trading safety (honeypot, rug pull, exit liquidity, smart money), see base-memecoin-guard-mcp.

Payments and limits

Variable	Default	Meaning
`X402_PRIVATE_KEY`	(unset)	Private key of a Base mainnet wallet you control that holds some USDC. Without it, `x402_recommend_preview` works and the paid tools return their price and setup steps, paying nothing.
`X402_MAX_PER_CALL_USD`	`0.30`	The most one call may pay.
`X402_SESSION_BUDGET_USD`	`2.00`	The most the server may spend until it restarts.

Use a dedicated hot wallet with a small balance. One dollar of USDC buys 100 checks or 200 recommendations.
No ETH is needed: x402 exact payments are gasless EIP-3009 USDC authorisations.
The key stays on your machine. It is never logged or returned, and it signs only the one request you made.
Payments go only to the facts402 receiving address (0x5498b0Aa90cd56F8962CBd136DF3D3769C85f149). A quote for any other payee, any other token or a Permit2 approval is refused.
Every paid answer comes with a receipt: amount, transaction hash and session totals.

Install

The server runs with uv (uvx facts402-mcp).

Claude Desktop

Add this to claude_desktop_config.json (Settings > Developer > Edit Config):

"mcpServers": { "facts402": { "command": "uvx", "args": ["facts402-mcp"], "env": { "X402_PRIVATE_KEY": "0xYOUR_HOT_WALLET_KEY", "X402_MAX_PER_CALL_USD": "0.30", "X402_SESSION_BUDGET_USD": "2.00" } } } }

Claude Code

claude mcp add facts402 --scope user -e X402_PRIVATE_KEY=0xYOUR_HOT_WALLET_KEY -- uvx facts402-mcp

Cursor

Use ~/.cursor/mcp.json (global) or .cursor/mcp.json (project; keep the key out of version control):

"mcpServers": { "facts402": { "command": "uvx", "args": ["facts402-mcp"], "env": { "X402_PRIVATE_KEY": "0xYOUR_HOT_WALLET_KEY" } } } }

Windsurf

Use ~/.codeium/windsurf/mcp_config.json:

"mcpServers": { "facts402": { "command": "uvx", "args": ["facts402-mcp"], "env": { "X402_PRIVATE_KEY": "0xYOUR_HOT_WALLET_KEY" } } } }

Example prompts

"Which paid API should I use for web search? Show me the cheapest live one with real buyers."
"Validate IBAN DE89 3704 0044 0532 0130 00 and tell me the bank."
"Is IE6388047V a valid VAT number? What company is it?"
"Screen 'Banco Nacional de Cuba' against OFAC sanctions."
"How many business days are there in Germany between 21 Dec 2026 and 8 Jan 2027?"

Development (both servers)

This folder also holds the shared core used by base-memecoin-guard-mcp: the HTTP caller, the x402 wallet, the budget and the server plumbing. From A2A_MICROPAYMENTS_TRACK/mcp:

python -m venv .venv

.venv/bin/pip install -e "./facts402-mcp[test]" -e "./base-memecoin-guard-mcp[test]" .venv/bin/pytest facts402-mcp && .venv/bin/pytest base-memecoin-guard-mcp # unit tests, mocked HTTP .venv/bin/pytest -m live facts402-mcp && .venv/bin/pytest -m live base-memecoin-guard-mcp # live, never pays .venv/bin/python scripts/sync_schemas.py # refresh input schemas and prices from the live /openapi.json .venv/bin/python scripts/write_manifest.py # refresh each manifest.json (MCPB) from the code

facts402: x402 API finder + fact checks

Overview

PopNx MCP’s three pillars

What you can do with it

Install

Before you install

Values you fill in

What it can do

Basic checksi

Maker matches the repo

Still maintained

Has a licence

Endpoint responds

Sign-in with OAuth

No hidden instructions in tool descriptions

Compared with others in Otheri

Common questions

Alternatives

Spec Driven Development

Remote Desktop Commander

Dialyne

README from the maker

facts402-mcp

Tools

Payments and limits

Install

Claude Desktop

Claude Code

Cursor

Windsurf

Example prompts

Development (both servers)