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PopNx MCPMCP servers for people who use AI · explained in plain words

crosscheck

by maxugcversion 0.6.0i★ 1 (Stars belong to another repo)iComputer or cloud
Registry namecom.crosscheckapi/crosscheck

How to install

What it does

Checks for AI agents over x402: review drafts, accept-check handoffs, scan skills before install.

  • Connects Computer or cloud
  • Account or key Cloud: No key needed · Local: Needs CROSSCHECK_WALLET_KEY
  • Category Other

Install

Pick the AI app you use, then copy the settings.

Passed 4/5 checks · What you ask goes through the maker’s server (crosscheckapi.com) · ✓ Commands checked Nov 13, 2026

First: which AI do you use?

Pick your app and the steps appear below.

Works with Claude · about 2 min

No key, nothing to install · Set it up once on claude.ai or the desktop app, then use it in chat · free accounts can add 1 · on Team/Enterprise an Owner adds it

  1. Open Claude’s Connectors page

    CustomizeConnectors

    CustomizeConnectors1Add2https://…3Add4
  2. Click “Add” → “Custom” → “Web” and fill in these 2 fields

    Copy each value into the field with the same name in Claude, then click Continue

    Name · Namecrosscheck
    Remote MCP server URL · Addresshttps://crosscheckapi.com/mcp

    Click Continue past the sign-in settings Claude detected · under Authentication choose what the maker says (Sign in now, Sign in when needed or No sign in), then click Add

  3. Turn it on in a chat

    +Connectorscrosscheck

  4. Try it

    Use crosscheck and tell me what you can do for me, then show me one thing

    ✓ If Claude says it is using crosscheck or shows a crosscheck tool in the answer, you are connected

Menu names checked against Anthropic’s help page on Nov 11, 2026 · your screen may differ slightly by app version

Works with ChatGPT, depending on your plan

Full MCP: ChatGPT Business, Enterprise or Edu on the web · Pro: connects with read/fetch permissions, so tools that change data may not work · Plus: not confirmed in OpenAI’s docs; if you see an add-custom-MCP option on the Plugins page you can try these steps · web only

  1. Open ChatGPT’s add-MCP page on the web

    Plugins+Add custom MCP server

    ChatGPTPlugins1+2https://…3Create4
  2. Fill in the name and address

    Enter a name, paste the address under Connection, tick the risk warning and click Create as a plugin

    Name · Namecrosscheck
    Connection · Addresshttps://crosscheckapi.com/mcp
  3. Pick crosscheck in a chat

    Start a new chat and pick crosscheck from your plugins before typing

  4. Try it

    Use crosscheck and tell me what you can do for me, then show me one thing

    ✓ If ChatGPT says it is using crosscheck or shows a crosscheck tool in the answer, you are connected

Menu names checked against OpenAI’s help page on Nov 11, 2026 · your screen may differ slightly by app version

Works with Claude Code · about 2 min

No key, nothing to install

  1. Open Terminal

    Mac: press Command+Space and type Terminal · Windows: open PowerShell

  2. Paste this command and press Enter

    claude mcp add --transport http --scope user crosscheck https://crosscheckapi.com/mcp
  3. Type /mcp in Claude Code

    You should see crosscheck listed as connected

  4. Try it

    Use crosscheck and tell me what you can do for me, then show me one thing

    ✓ If Claude Code says it is using crosscheck or shows a crosscheck tool in the answer, you are connected

Menu names checked against Anthropic’s help page on Nov 11, 2026 · your screen may differ slightly by app version

Works with Cursor · about 2 min

No key, nothing to install

  1. Click this button to open Cursor

    Open in Cursor

    Cursor asks you to confirm; click Install

  2. Open the AI chat in Cursor in Agent mode

  3. Try it

    Use crosscheck and tell me what you can do for me, then show me one thing

    ✓ If Cursor says it is using crosscheck or shows a crosscheck tool in the answer, you are connected

Menu names checked against Cursor’s help page on Nov 11, 2026 · your screen may differ slightly by app version

Works with VS Code · about 2 min

No key, nothing to install

  1. Click this button to open VS Code

    Open in VS Code

    VS Code asks you to confirm; click Install

  2. Open the AI chat in VS Code in Agent mode

  3. Try it

    Use crosscheck and tell me what you can do for me, then show me one thing

    ✓ If VS Code says it is using crosscheck or shows a crosscheck tool in the answer, you are connected

Menu names checked against VS Code’s help page on Nov 11, 2026 · your screen may differ slightly by app version

Other apps that use MCP, such as Windsurf, Zed or Gemini CLI, each add servers differently. See how in the app list.

See every app that uses MCP →

Address for apps that connect over the web

Addresshttps://crosscheckapi.com/mcp

JSON settings are under “For developers” below

Stuck? Ask people who use crosscheck💬 Discussion →
For developers: Terminal commands and JSON settings

Over the web

Claude Code

claude mcp add --transport http --scope user crosscheck https://crosscheckapi.com/mcp

Cursor (~/.cursor/mcp.json)

{
  "mcpServers": {
    "crosscheck": {
      "url": "https://crosscheckapi.com/mcp"
    }
  }
}

VS Code (mcp.json)

{
  "servers": {
    "crosscheck": {
      "type": "http",
      "url": "https://crosscheckapi.com/mcp"
    }
  }
}

Installed on your computer

Claude Code

claude mcp add --scope user crosscheck --env CROSSCHECK_WALLET_KEY=your-value --env CROSSCHECK_MAX_USD=your-value --env CROSSCHECK_NETWORKS=your-value -- npx -y crosscheckapi

Claude Desktop (claude_desktop_config.json)

{
  "mcpServers": {
    "crosscheck": {
      "command": "npx",
      "args": [
        "-y",
        "crosscheckapi"
      ],
      "env": {
        "CROSSCHECK_WALLET_KEY": "your-value",
        "CROSSCHECK_MAX_USD": "your-value",
        "CROSSCHECK_NETWORKS": "your-value"
      }
    }
  }
}

Cursor (~/.cursor/mcp.json)

{
  "mcpServers": {
    "crosscheck": {
      "command": "npx",
      "args": [
        "-y",
        "crosscheckapi"
      ],
      "env": {
        "CROSSCHECK_WALLET_KEY": "your-value",
        "CROSSCHECK_MAX_USD": "your-value",
        "CROSSCHECK_NETWORKS": "your-value"
      }
    }
  }
}

VS Code (mcp.json)

{
  "servers": {
    "crosscheck": {
      "type": "stdio",
      "command": "npx",
      "args": [
        "-y",
        "crosscheckapi"
      ],
      "env": {
        "CROSSCHECK_WALLET_KEY": "your-value",
        "CROSSCHECK_MAX_USD": "your-value",
        "CROSSCHECK_NETWORKS": "your-value"
      }
    }
  }
}

Values you fill in

  • CROSSCHECK_WALLET_KEY secret env
    Private key of a dedicated EVM wallet with a few dollars of USDC on Base (or test USDC on Base Sepolia). Pays for checks.
  • CROSSCHECK_MAX_USD env
    Refuse to pay more than this per check. Default 0.10.
  • CROSSCHECK_NETWORKS env
    Networks to pay on, in order of preference. Default eip155:8453,eip155:84532. Set eip155:84532 for test USDC only.

These settings are generated from the maker’s registry entry. If the README says otherwise, follow the README.

At a glance

GitHub starsi
1 (Stars belong to another repo)
This listing points to someone else’s repo, so its stars are not counted in rankings
Downloads per weeki
124/wk
Verified domain
✓ crosscheckapi.com
Connection
Computer or cloud
Transport
stdio, streamable-http
Latest versioni
0.6.0
Categoryi
Other
Published to registryi
Oct 25, 2026
Code last changedi
Oct 25, 2026
Maker
maxugc
Packages
npm: crosscheckapi
Registry status
Active

Which apps can use it

Based on how this server connects and on each app’s own docs, checked Nov 10, 2026.

Connect over the internet in

ClaudeChatGPTGooseLM StudioMsty StudioCherry StudioCursorVS Code + GitHub CopilotVisual StudioWindsurf (Devin Desktop)ZedKiroClineContinueJetBrains AI AssistantClaude CodeCodex CLIGemini CLIOpenCodenodecodeWarpLibreChatOpen WebUIRaycast

Run on your computer in

ClaudeGooseLM StudioMsty StudioCherry StudioCursorVS Code + GitHub CopilotVisual StudioWindsurf (Devin Desktop)ZedKiroClineContinueJetBrains AI AssistantClaude CodeCodex CLIGemini CLIOpenCodenodecodeWarpLibreChatRaycast

All apps, with pros and cons →

Related guides

What it can do

Tool names and descriptions exactly as the server reported them on Nov 12, 2026. The maker wrote them, not us; we show them as plain text.

  • check

    Independent review of a draft (email, report, summary, PR description) before its human sees it. Returns pass or specific issues with fixes; arithmetic is recomputed in code. With request (what the human asked), it also checks the draft answers that. With sources, each claim is c

  • accept

    Checks work another agent handed back against the task it was given, before you pay, release escrow, or pass it on. Returns accept, reject, or verify_externally with every requirement judged; counts, required JSON fields, and sums are checked in code. Optional payment_tx is verif

  • skillcheck

    Security review of a skill or MCP server's files before you install or connect it: read, never run. Free when these exact files were scanned before (looked up by bundle hash); otherwise paid, $0.03 base. Never says safe. Paid per call in USDC over x402 (Base, or free test USDC on

  • sellercheck

    For x402 sellers: one dated report on your own paid resource, by code alone. Does it answer a valid 402 (v1 or v2: price, network, payTo), is it in the x402 Bazaar index, would agent402's router route to it, and how many USDC settlements reached its payTo on Base in 24 hours and

  • sellerwatch

    For x402 sellers: sellercheck every hour for 30 days on one resource, paid once. An alert to your webhook (JSON POST) or ntfy topic only when something changes: the 402 breaks or its price or payTo change, it leaves or rejoins the Bazaar index, agent402's router flips, settlement

  • skillcheck_lookup

    Free. The latest skillcheck of an exact bundle, by its bundle_sha256 (SHA-256 of the canonical JSON of the files sorted by path, each as {path, sha256}).

  • verify_receipt

    Free. Before trusting work that arrives with a crosscheck receipt, check in code that crosscheck issued it, its signature is valid, what the outcome was, and that it covers exactly the text you were handed. Pass receipt_hash (or the receipt object) plus that text: draft, request,

  • result

    Free. Status, verdict, and signed receipt of an earlier paid call that was still running, using the job_id and result_token it returned.

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 13, 2026

  • ! Caution

    Maker matches the repo

    The publisher (crosscheckapi.com) is not the repo owner (maxugc); someone else may have listed it

  • ✓ Pass

    Still maintained

    Code last changed 19 days ago

  • ✓ Pass

    Has a licence

    Uses MIT

  • ✓ Pass

    Endpoint responds

    Responded in 431 ms (HTTP 200)

  • – Not applicable

    Sign-in with OAuth

    No sign-in needed

  • ✓ Pass

    No hidden instructions in tool descriptions

    Read 8 tool descriptions and found no hidden instructions to the AI

Discussion

Ask, share a tip or report that it does not work. Sorted by what people marked helpful.

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User reviews

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Compared with others in Otheri

  • More stars than 0% of the other 19481 servers in this category
  • Published to the registry more recently than 68% of the other 19481 servers in this category
  • Basic checks equal to or better than 60% of the other 19481 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 crosscheck safe?

It passed 4 of 5 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: CROSSCHECK_WALLET_KEY

Does it run on my computer or in the cloud?

Either way works: install it on your computer or connect to the cloud version.

Is it still maintained?

The GitHub repo last changed 19 days ago, and the latest version (0.6.0) reached the registry 19 days ago.

Which apps can use it?

Apps that support MCP, such as Claude Desktop, Claude Code, Cursor and VS Code. It connects by URL, so apps that accept remote MCP servers work too, such as ChatGPT on the web (full MCP on Business and above; Pro read-only).

What can I use instead?

In the same category: World Monitor, Claude Flow, Windmill

Others in the same category

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

World Monitor

Real-time global intelligence on conflict, markets, energy, trade, shipping and cyber. 104 tools.

by koala73Widely used★ 90.5KUpdated yesterday

Runs in the cloud✓ service owner · worldmonitor.app

Claude Flow

AI orchestration with hive-mind swarms, neural networks, and 87 MCP tools for enterprise dev.

by ruvnetWidely used↓ 13.5K/wk★ 81.5KUpdated 14 months ago

Runs on your computer

Windmill

Run Windmill scripts and flows and manage jobs, schedules, resources and variables.

by windmill-labsWidely used★ 18.6KUpdated yesterday

Runs in the cloud

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.

crosscheckapi

An independent second opinion on a draft before your human sees it.

Your agent sends the text it wrote: an email, report, message, PR description, or summary. crosscheck returns a JSON verdict, either pass or a list of specific issues with fixes, plus an Ed25519-signed receipt. It catches wrong arithmetic (checked in code, not by the model), contradictions, leftover placeholders, leaked secrets, unauthorized commitments, and prompt injection. Each check costs $0.02 in USDC on Base for up to 12,000 units (one per English character), paid per request over x402. There is no account and no API key.

To try it without real money, pay with test USDC on Base Sepolia (free at https://faucet.circle.com) and set CROSSCHECK_NETWORKS=eip155:84532.

MCP server

{

"mcpServers": { "crosscheck": { "command": "npx", "args": ["-y", "crosscheckapi"], "env": { "CROSSCHECK_WALLET_KEY": "0x " } } } }

Tools:

  • quote: free. The price for a draft, and whether checks are available now.
  • order: pays the quoted price and returns the verdict and signed receipt. Pass moltbook_identity to use a free check if you are a verified Moltbook agent. Optional: request (what your human asked, word for word; the draft fails if it answers a different question or leaves part out), sources (text the draft relies on), source_urls (up to 3 pages crosscheck opens and checks the draft against, +$0.01 each), and fetch_cited (also open the draft's own links).
  • accept: pays about $0.03 and checks work another agent or service handed back against the task you gave it. Returns accept or reject with each requirement judged, before you pay for the work or pass it on.
  • skillcheck: security-checks a skill or MCP server folder before you install it. Free when someone already scanned the same files, otherwise about $0.03.
  • result: free. Status, verdict, and receipt of an earlier order.

CLI

npx -p crosscheckapi crosscheck quote draft.txt

npx -p crosscheckapi crosscheck order draft.txt npx -p crosscheckapi crosscheck accept task.txt deliverable.txt npx -p crosscheckapi crosscheck skillcheck ./some-skill npx -p crosscheckapi crosscheck result npx -p crosscheckapi crosscheck credits [wallet] npx -p crosscheckapi crosscheck order draft.txt --request "What will 12 seats cost per year?" --url https://example.com/pricing

The draft is read from the file, or from stdin if no file is given. Output is JSON.

Referrals: the paid commands (order, accept, skillcheck) take --ref , the id in a crosscheck proof link (/r/ ) that led you here. When your wallet's first check paid in real USDC carries a ref, the wallet behind that receipt earns check credits worth 20% of what you pay for 90 days; it costs you nothing. --credits pays with your own wallet's referral credits by signing a credit order instead of paying, and falls back to USDC only when the credits do not cover the price. crosscheck credits shows your balance. The MCP tools take the same options as ref and credits, and add a free credits tool.

Settings

VariableMeaning
CROSSCHECK_WALLET_KEYPrivate key of the wallet that pays. Use a dedicated wallet holding a few dollars, never your main wallet. Only needed for paid orders.
CROSSCHECK_MAX_USDRefuse to pay more than this per check. Default 0.10.
CROSSCHECK_URLService URL. Default https://crosscheckapi.com.
CROSSCHECK_NETWORKSNetworks the client may pay on, in order of preference. Default eip155:8453,eip155:84532 (Base, then Base Sepolia). Set eip155:84532 to use test USDC only.

Receipts

Every paid check returns receipt with body, hash, and sig. The client verifies it automatically against the public key at https://crosscheckapi.com/.well-known/crosscheck-keys.json and reports receipt_check.valid. The receipt covers a SHA-256 of your draft (never the text), the payment, and a SHA-256 of the verdict, and it is chained into an append-only ledger.

Privacy

The draft is sent to crosscheck and to its review model, then deleted when the check finishes. Only its hash is kept. Do not send text your human has marked confidential.

Source, examples for Claude Code, Cursor, VS Code, OpenAI Agents SDK, LangChain, and more: https://github.com/maxugc/crosscheck

Service summary for agents: https://crosscheckapi.com/llms.txt