aba-payway-mcp

Open source. Unofficial. Community-built. This is not an ABA Bank or PayWay product, and it isn't endorsed, reviewed, or supported by them — it's an independent MCP wrapper around their publicly documented API. Use it at your own risk, review the code before pointing it at production credentials, and see LICENSE for the full disclaimer.

An MCP (Model Context Protocol) server that wraps ABA Bank's PayWay API (https://developer.payway.com.kh) so any MCP-compatible AI tool — Claude Code, Claude Desktop, Cursor, Windsurf, Cline, VS Code/Copilot, Gemini CLI, or any other MCP client — can create checkouts, generate KHQR codes, check/list transactions, issue refunds, create payment links, and pull exchange rates, directly from a chat or agent session.

Released under the MIT license — free to use, fork, modify, and redistribute. Built from the public PayWay developer docs (Ecommerce Checkout, ABA QR API, Payment Link, KHQR Guideline sections). PRs and issues welcome; see Contributing.

Tools

Every hash is generated in the exact field order PayWay's docs specify per endpoint (req_time/request_time + merchant_id + ... + your api_key, HMAC-SHA512, base64) — this matters because a wrong field order produces a valid-looking hash that PayWay silently rejects. merchant_auth fields (Refund, Payment Link) are RSA-PKCS1 encrypted in 117-byte chunks, matching PayWay's own PHP sample code exactly (openssl_public_encrypt default padding, not OAEP).

Related MCP server: Bayarcash MCP Server

Requirements

• Node.js 18+

• A PayWay sandbox or production merchant profile (sandbox sign-up: https://sandbox.payway.com.kh/register-sandbox/, production: contact paywaysales@ababank.com)

• Your server's egress IP whitelisted with PayWay — this server calls the API directly (not from a browser), so PayWay needs to allow that IP, not just a frontend domain.

Install

Clone and run locally:

git clone https://github.com/sim0ple/aba-payway-mcp.git
cd aba-payway-mcp
npm install

Or, once published to npm, run it with npx without cloning anything (see per-client examples below) — npx -y aba-payway-mcp.

Configuration

Set as environment variables in your MCP client's config (never hardcode secrets in code or commit them):

Adding it to your AI tool

Every client below ultimately runs the same command:

node /absolute/path/to/aba-payway-mcp/src/index.js

(or npx -y aba-payway-mcp once it's published to npm). Only the configuration mechanism differs per tool.

Claude Code (CLI)

Claude Code has a built-in claude mcp add command. Everything after -- is the command it runs to start the server; flags before -- configure how Claude Code registers it.

claude mcp add payway \
  --env PAYWAY_MERCHANT_ID=your_merchant_id \
  --env PAYWAY_API_KEY=your_api_key \
  --env PAYWAY_ENV=sandbox \
  -- node /absolute/path/to/aba-payway-mcp/src/index.js

Add --env PAYWAY_RSA_PUBLIC_KEY="$(cat your_key.pem)" if you need the refund / payment-link tools.

Once published to npm, you can skip the clone entirely:

claude mcp add payway \
  --env PAYWAY_MERCHANT_ID=your_merchant_id \
  --env PAYWAY_API_KEY=your_api_key \
  --env PAYWAY_ENV=sandbox \
  -- npx -y aba-payway-mcp

Useful follow-ups:

claude mcp list                 # check connection status
claude mcp get payway           # see the exact command/env Claude Code stored
claude mcp remove payway        # remove it

Scope — by default claude mcp add registers the server at local scope (just you, just this project). Pass --scope user to make it available in every project on your machine, or --scope project to write it to .mcp.json at the project root so teammates get it too when they clone the repo (they'll be prompted to approve it — don't commit real secrets, reference them as ${PAYWAY_API_KEY} and set that env var per machine, or use a .env your team doesn't commit):

claude mcp add --scope project payway \
  --env PAYWAY_MERCHANT_ID='${PAYWAY_MERCHANT_ID}' \
  --env PAYWAY_API_KEY='${PAYWAY_API_KEY}' \
  -- npx -y aba-payway-mcp

If you'd rather write the config by hand, this is the equivalent .mcp.json entry (project scope) or ~/.claude.json entry (user scope):

{
  "mcpServers": {
    "payway": {
      "type": "stdio",
      "command": "npx",
      "args": ["-y", "aba-payway-mcp"],
      "env": {
        "PAYWAY_MERCHANT_ID": "your_merchant_id",
        "PAYWAY_API_KEY": "your_api_key",
        "PAYWAY_ENV": "sandbox"
      }
    }
  }
}

Claude Desktop

Settings → Developer → Edit Config opens claude_desktop_config.json:

{
  "mcpServers": {
    "payway": {
      "command": "npx",
      "args": ["-y", "aba-payway-mcp"],
      "env": {
        "PAYWAY_MERCHANT_ID": "your_merchant_id",
        "PAYWAY_API_KEY": "your_api_key",
        "PAYWAY_ENV": "sandbox",
        "PAYWAY_RSA_PUBLIC_KEY": "-----BEGIN PUBLIC KEY-----\n...\n-----END PUBLIC KEY-----"
      }
    }
  }
}

Restart Claude Desktop to pick up the change.

Cursor

.cursor/mcp.json in your project (project-scoped) or the global one via Cursor Settings → MCP (available everywhere):

{
  "mcpServers": {
    "payway": {
      "command": "npx",
      "args": ["-y", "aba-payway-mcp"],
      "env": {
        "PAYWAY_MERCHANT_ID": "your_merchant_id",
        "PAYWAY_API_KEY": "your_api_key",
        "PAYWAY_ENV": "sandbox"
      }
    }
  }
}

Windsurf

Edit ~/.codeium/windsurf/mcp_config.json directly (macOS/Linux) or %USERPROFILE%\.codeium\windsurf\mcp_config.json (Windows) — or open it via the hammer icon in Cascade → Configure:

{
  "mcpServers": {
    "payway": {
      "command": "npx",
      "args": ["-y", "aba-payway-mcp"],
      "env": {
        "PAYWAY_MERCHANT_ID": "your_merchant_id",
        "PAYWAY_API_KEY": "your_api_key",
        "PAYWAY_ENV": "sandbox"
      }
    }
  }
}

Cline (VS Code extension)

Open the Cline sidebar → MCP Servers icon → "Edit MCP Settings" (or cline_mcp_settings.json directly), same mcpServers shape:

{
  "mcpServers": {
    "payway": {
      "command": "npx",
      "args": ["-y", "aba-payway-mcp"],
      "env": {
        "PAYWAY_MERCHANT_ID": "your_merchant_id",
        "PAYWAY_API_KEY": "your_api_key",
        "PAYWAY_ENV": "sandbox"
      }
    }
  }
}

VS Code (GitHub Copilot)

VS Code can add an MCP server straight from the command line:

code --add-mcp '{"name":"payway","command":"npx","args":["-y","aba-payway-mcp"],"env":{"PAYWAY_MERCHANT_ID":"your_merchant_id","PAYWAY_API_KEY":"your_api_key","PAYWAY_ENV":"sandbox"}}'

Or via the Command Palette → MCP: Add Server, or by hand in .vscode/mcp.json (workspace) / user mcp.json (global):

{
  "servers": {
    "payway": {
      "type": "stdio",
      "command": "npx",
      "args": ["-y", "aba-payway-mcp"],
      "env": {
        "PAYWAY_MERCHANT_ID": "your_merchant_id",
        "PAYWAY_API_KEY": "your_api_key",
        "PAYWAY_ENV": "sandbox"
      }
    }
  }
}

Gemini CLI

Gemini CLI also has a native add subcommand:

gemini mcp add payway \
  -e PAYWAY_MERCHANT_ID=your_merchant_id \
  -e PAYWAY_API_KEY=your_api_key \
  -e PAYWAY_ENV=sandbox \
  -- npx -y aba-payway-mcp

-s user (default project) makes it available across all your projects instead of just the current one:

gemini mcp add -s user payway -e PAYWAY_MERCHANT_ID=your_merchant_id -e PAYWAY_API_KEY=your_api_key -- npx -y aba-payway-mcp

This writes to ~/.gemini/settings.json (user) or .gemini/settings.json (project).

Any other MCP client

If your tool isn't listed above, it almost certainly still reads the same shape — an mcpServers (or servers) object with command, args, and env:

{
  "mcpServers": {
    "payway": {
      "command": "npx",
      "args": ["-y", "aba-payway-mcp"],
      "env": {
        "PAYWAY_MERCHANT_ID": "your_merchant_id",
        "PAYWAY_API_KEY": "your_api_key",
        "PAYWAY_ENV": "sandbox"
      }
    }
  }
}

Point command at node with the absolute path to src/index.js instead of npx if you're running from a local clone rather than a published npm package. Check your client's docs for the exact config file path and key name (mcpServers vs servers is the main variant).

Local smoke test (no live PayWay credentials needed)

npm test

This spawns the server over stdio, does the MCP initialize handshake, lists all 11 tools, and calls payway_exchange_rate with dummy credentials to confirm the hashing/config code path runs (it'll get a network/auth error against real PayWay, which is expected without real creds — the point is confirming nothing throws before that).

Notes / gotchas carried over from the PayWay docs

• payway_purchase with no payment_option and hosted_view returns full checkout HTML (a redirect page) rather than JSON — that's normal PayWay behavior, not a bug here.

• payway_check_transaction only works ≤7 days old; use payway_get_transaction_details for older transactions.

• payway_get_transaction_list date range is capped at 3 days by PayWay.

• Refunds only work on COMPLETED/APPROVED transactions within 30 days.

• Amount/currency minimums (100 KHR / 0.01 USD, etc.) are enforced by PayWay itself, not duplicated here — check status.code in the response if something's rejected.

Project layout

aba-payway-mcp/
├── package.json
├── src/
│   ├── index.js    # MCP server + all tool definitions
│   └── payway.js   # HMAC hashing / RSA encryption / HTTP client
├── test/           # stdio smoke tests, no live credentials required
├── .env.example
└── .github/workflows/ci.yml

Contributing

This is an open-source, community-maintained project — issues and PRs welcome, especially for the remaining PayWay sections not yet covered (Credentials on File / tokenized payments, Pre-auth capture flow, multi-party Payout, Shopify/WooCommerce/Prestashop plugin helpers).

Disclaimer

aba-payway-mcp is an unofficial, independently developed integration. It is not created by, affiliated with, or endorsed by ABA Bank or PayWay. "PayWay" and "ABA" are trademarks of their respective owners. Provided as-is, with no warranty — see LICENSE.

License

MIT — free and open source. See LICENSE.