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

Mahshar

by sharken3948version 1.0.0i★ 3iRuns in the cloud
Registry nameio.github.sharken3948/mahshar

Install

Overview

Description from the maker (original English)

Free API discovery for AI agents; execution may require USDC/x402 payments on Arc Mainnet.

PopNx MCP’s three pillars

These three are never merged into one score: opinions, measurements and popularity are different things.

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.

Install

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

Before you install

You need

Which app do you use?

Pick your app above. We remember it, so next time the button says “Install in …”.

Works in Claude on the web, desktop and mobile:

  1. Open Settings → Connectors
  2. Press Add custom connector
  3. Paste the address below and press Add
  4. If it asks you to sign in, sign in with the maker
SettingsConnectors1+ Add2https://…3Connect4
https://mahshar.xyz/api/mcp

Run this in your terminal

claude mcp add --transport http mahshar https://mahshar.xyz/api/mcp

Open in Cursor

Or copy the settings yourself

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

{
  "mcpServers": {
    "mahshar": {
      "url": "https://mahshar.xyz/api/mcp"
    }
  }
}

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": {
    "mahshar": {
      "type": "http",
      "url": "https://mahshar.xyz/api/mcp"
    }
  }
}

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.

ChatGPT connects only to servers on the internet:

  1. Open ChatGPT on the web → Settings → Connectors (Apps)
  2. Press Create or Add (some plans need Developer mode under Advanced first)
  3. Paste the address below, give it a name and save
  4. If it asks you to sign in, sign in with the maker
SettingsConnectors1+ Create2https://…3Connect4
https://mahshar.xyz/api/mcp

Menu names can differ slightly by plan and over time.

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.

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

All apps, with pros and cons →

What it can do

The server did not answer when we last checked, so we could not read its tools.

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 11, 2026

  • ✓ Pass

    Maker matches the repo

    The registry name was verified with the GitHub account sharken3948, which owns the repo

  • ✓ Pass

    Still maintained

    Code last changed 2 days ago

  • … Not checked yet

    Has a licence

    We have not read this repo from GitHub yet

  • ✕ Fail

    Endpoint responds

    Did not respond within 6 seconds when we checked

  • – Not applicable

    Sign-in with OAuth

    Did not respond within 6 seconds when we checked

  • … Not checked yet

    No hidden instructions in tool descriptions

    Not checked yet; we read the tool list when we check the endpoint

Compared with others in Otheri

  • More stars than 91% of the other 19101 servers in this category
  • Published to the registry more recently than 78% of the other 19101 servers in this category
  • Basic checks equal to or better than 40% of the other 19101 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 Mahshar safe?

It passed 2 of 3 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 in the maker’s cloud. Connect over the internet with nothing to install, but what you send passes through the maker’s servers.

Is it still maintained?

The GitHub repo last changed 2 days ago, and the latest version (1.0.0) reached the registry 11 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 in developer mode.

What can I use instead?

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

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

World Monitor

Real-time global intelligence on conflict, markets, energy, trade, shipping and cyber. 102 tools.

by koala73Widely used★ 90.4KUpdated 6 days ago

Runs in the cloud✓ 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★ 81.4KUpdated 14 months ago

Runs on your computer

Tldraw

Draw and visually collaborate with your agents on tldraw's canvas.

by tldrawWidely used★ 51.4KUpdated 8 months ago

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.

Mahshar

The API marketplace for humans and autonomous agents, powered by USDC on Arc.

Mahshar lets API providers monetize existing endpoints without rebuilding billing infrastructure. Buyers and autonomous agents can discover APIs, pay per call in USDC, and receive responses through Mahshar's payment-aware proxy.

What Mahshar Does

For sellers:

  • List an existing API without changing its backend.
  • Set a USDC price per call.
  • Support public or credential-protected upstream APIs.
  • Keep upstream credentials hidden from buyers.
  • Track calls, earnings, and withdrawal state.
  • Receive seller earnings through the marketplace accounting flow.

For buyers and agents:

  • Discover APIs programmatically.
  • Inspect machine-readable API metadata.
  • Pay per request using USDC.
  • Retrieve responses tied to the exact purchase.
  • Never receive the seller's upstream credentials.

Public Discovery and Buyer Application

Mahshar provides crawlable public discovery surfaces without requiring a wallet connection:

The public discovery layer is isolated from wallet authentication, payment execution, and proxy behavior. The wallet-enabled /buyer application remains the place to connect a wallet and execute paid API requests.

Supported Upstream Authentication

ModelUpstream behavior
Public APINo credential is added.
API KeyA stored API key is injected as an authorized header only after target validation.
Bearer TokenA stored bearer credential is injected into the Authorization header only after target validation.
Query CredentialA stored credential is added as the configured query parameter only after canonical target authorization.
HTTP BasicAn encrypted username/password bundle is applied server-side after target validation.
Custom Credential HeadersOne or more encrypted header values use configured, validated header names.
Custom AuthorizationA validated Token or ApiKey Authorization scheme is applied server-side.
OAuth 2.0 Client CredentialsAn approved provider profile uses a seller-owned connection; configuration and access tokens remain encrypted server-side.

The Client Credentials profile must be enabled by the operator. Authorization Code + PKCE is present in the implementation but disabled in Production. An active provider connection does not activate a listing; publication still requires verification. Stored credentials and tokens are server-side data and are not included in buyer responses or public discovery metadata. Provider authentication details.

How a Paid API Call Works

Buyer / Agent

→ Discover API → Request paid endpoint → x402 payment requirement → USDC settlement → Canonical target authorization → Seller credential injected server-side where required → Upstream API → Durable purchase-scoped response → Buyer / Agent

Settlement, delivery, and response recovery have distinct durable identities. A recovery capability can retrieve only the response associated with its exact purchase.

Beyond the Arc Reference Apps

circlefin/arc-commerce demonstrates purchasing application credits with USDC, while circlefin/arc-p2p-payments demonstrates wallet-based peer-to-peer payments.

Mahshar adds application-layer primitives for machine-readable paid API discovery, MCP-native discovery and externally signed execution, x402 pay-per-call API monetization, canonical upstream authorization before credential injection, server-side seller credential isolation, prepared-call integrity, purchase-scoped response recovery, and durable payment, settlement, accounting, and delivery state handling.

Mahshar composes existing x402, MCP, Circle Gateway, USDC, Arc wallet, CCTP, and bridge infrastructure; it does not claim to have invented those technologies. See Reusable Arc primitives for implementation boundaries, verification status, and extraction requirements.

Arc Mainnet

Mahshar's production network is Arc Mainnet, chain ID 5042 (eip155:5042). Marketplace prices, buyer payments, platform accounting, and seller earnings are denominated in USDC.

Public Arc Mainnet Verification

Mahshar-owned:

The public address above is Mahshar's platform wallet on Arc Mainnet. The linked historical transaction is a successful call from that wallet to the official Arc Memo contract and can be independently verified in the Arc explorer. It is evidence of Mainnet operation and is not presented as independent proof of an x402 buyer purchase. Private signing material is never committed to the repository.

Automatic Memo writes have been removed. The linked transaction remains historical Mainnet evidence; paid API execution relies on Circle Gateway settlement and durable purchase, delivery, and response records, with no auxiliary platform-wallet transaction.

Official Arc/Circle contracts currently used by Mahshar:

ContractAddress
Arc USDC0x3600000000000000000000000000000000000000
Gateway Wallet0x77777777Dcc4d5A8B6E418Fd04D8997ef11000eE
Gateway Minter0x2222222d7164433c4C09B0b0D809a9b52C04C205

These are official system contracts, not Mahshar contracts. Mahshar currently deploys no custom smart contract.

The installed Circle x402 runtime requires explicit Arc Mainnet RPC configuration and its current Mainnet compatibility settings. See .env.example and agent integration for the repository's operational contract.

Wallet Authentication

Normal browser authentication is designed to avoid repeated signature prompts:

Connect wallet

→ Sign one login challenge → Fixed eight-hour authenticated session → Use normal marketplace features without repeated wallet prompts

The server stores an opaque, wallet-bound session in an HttpOnly cookie. The session has a fixed expiry and does not become permanent through activity. Wallet changes isolate private state and require authentication for the newly connected wallet.

Fresh operation-specific signatures remain required for:

  • Seller withdrawals.
  • endpoint_url changes.
  • auth_type changes.
  • Stored credential, OAuth configuration, or provider connection changes.
  • Authentication parameter-name changes.
  • HTTP method changes.
  • Dynamic-path, path-parameter, or query-parameter security-contract changes.

Normal navigation, private reads, and edits to names, descriptions, categories, prices, examples, documentation, and other presentation fields use the existing session.

Security Architecture

Mahshar includes layered controls for payment-aware proxying and wallet-scoped marketplace data:

  • Canonical upstream target validation before credential injection.
  • Traversal and encoded-traversal rejection.
  • Declared dynamic-path and query-parameter contracts.
  • Duplicate-query and credential-query collision protection.
  • Seller credential non-disclosure.
  • Purchase-scoped response recovery.
  • Durable x402 settlement and delivery state.
  • Atomic seller withdrawal reservations.
  • Durable fencing for ambiguous external execution.
  • Wallet-scoped private buyer and seller data.
  • Independent wallet and trusted-IP rate-limit buckets where applicable.
  • Bounded serialized response delivery.
  • A bounded declarative path/query matcher rather than arbitrary request-path JavaScript regular expressions.
  • Bounded response-retention and wallet-authentication pruning.
  • Origin and Fetch Metadata checks for session-authenticated mutations.
  • Fresh one-use operation authorization for sensitive listing changes.

These controls reduce identified risks; they are not a claim that the system is vulnerability-free. See Security documentation and SECURITY.md.

API Response Safety

Seller verification measures a representative serialized response. A response near Mahshar's delivery limit produces a seller-visible warning, and an over-limit representative response cannot complete verification. The runtime serialized-response limit remains authoritative for every paid delivery.

Verification observes one response and cannot guarantee that the upstream API will return the same size later.

Seller Withdrawals

Before external withdrawal work begins, Mahshar creates an atomic database reservation against the seller's currently available earnings. Concurrent requests cannot reserve the same earnings twice.

If submission or mint execution becomes ambiguous, the reservation remains locked in a recoverable submission_unknown or mint_unknown state. Confirmation and reconciliation are idempotent, and ambiguous money-moving operations are not blindly retried. The dashboard presents a status-check action instead of offering a duplicate withdrawal.

Machine Discovery

Autonomous clients should start with the public discovery endpoint and its current machine contract:

  • MCP V1 endpoint: https://mahshar.xyz/api/mcp (stateless discovery through search_apis and get_api, real x402 challenge preparation and externally signed replay through execute_api_call, and purchase-capability recovery through get_purchase_response). Mahshar never accepts buyer private keys, signs automatically, or takes custody. A scripted external MCP Canary verified four paid Production executions covering HTTP Basic, custom API-key header, custom Authorization token, and multiple credential headers. All four responses and purchase-scoped recoveries succeeded, with matching application accounting and no observed duplicate payment or credential exposure. Gateway nanopayment balances updated; final onchain batch settlement was not independently verified. This was a scripted harness, not a fully autonomous AI agent. Earlier external-client verification also covered same-authorization replay without duplicate payment.
  • OpenAPI document
  • Agent integration guide

Runtime discovery and OpenAPI URLs are generated from the configured canonical marketplace origin.

Admin Acquisition

The first bounded Production mock canary completed successfully. Continuous draft-only acquisition is deployed. Execution follows operator-approved configuration and Admin Start/Stop controls. All server-only acquisition flags default to false; the existing bounded Discovery Worker remains the default. Enabling acquisition flags requires separate operator approval; deployment does not start the Worker. The consumed canary and historical invitations remain preserved.

The Brevo acquisition delivery integration is deployed with real sending disabled by default. Immutable acquisition drafts and simulated results remain separate from ordinary Admin Outreach messages. A separately authorized real del

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