CheckDigit MCP server
Commit Oct 18, 2026Validates formats for IBAN, BIC, EU VAT, GTIN/EAN/UPC, and ISBN using offline check-digit algorithms.
Also known as miketusa-ctrl/checkdigit
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- Oct 18, 2026
- License
- MIT
What is CheckDigit MCP?
CheckDigit validates formats for IBAN, BIC, EU VAT, GTIN/EAN/UPC, and ISBN using offline check-digit algorithms.
Summary generated from the project's README
About CheckDigit MCP server
Verifying the structural integrity of identification numbers like IBAN, BIC, EU VAT, GTIN, EAN, UPC, and ISBN is what this remote MCP server enables for developers. By using offline check-digit algorithms, it provides format-only validation to ensure that specific codes follow the correct mathematical patterns without needing to query external databases for every check.
Users connect to this service as a remote HTTP or streamable HTTP server. It is compatible with AI clients such as Cursor, Windsurf, and Cline, while Claude Desktop users can add it via custom connectors or use the mcp-remote bridge. The server provides two specific tools: validate_code for checking formats and get_meta for retrieving additional information.
Developers who want to host their own instance can do so using Node.js 22+ and a Cloudflare account. Setting up a private version requires configuring wrangler.toml with specific KV namespaces, D1 databases, and rate-limit namespaces.
What you can do with it
- 1Validate financial identifiersAn AI assistant can check if a provided IBAN or BIC follows the correct format.
- 2Verify product and book codesYou can ask an AI to confirm that a GTIN, EAN, UPC, or ISBN is mathematically valid.
- 3Check European tax identifiersA developer can use the validate_code tool to ensure an EU VAT number is formatted correctly.
Written from the project's README. Every use case is checked against a quote from it.
README
View on GitHubCheckDigit
Offline check-digit validation for IBAN, BIC, EU VAT, GTIN/EAN/UPC and ISBN. Format check only.
Live service
- Web app and API: https://checkdigit.mike-tusa.workers.dev/
- Pricing: https://checkdigit.mike-tusa.workers.dev/docs
- Support: digitalpromohub.support@gmail.com
Use it from an AI assistant (MCP)
CheckDigit is a remote MCP server (Streamable HTTP) at https://checkdigit.mike-tusa.workers.dev/mcp. Tools: validate_code, get_meta.
Cursor and Windsurf accept this config:
{
"mcpServers": {
"checkdigit": {
"type": "http",
"url": "https://checkdigit.mike-tusa.workers.dev/mcp"
}
}
}
Cline (MCP Servers > Remote Servers, or cline_mcp_settings.json) needs "type": "streamableHttp":
{
"mcpServers": {
"checkdigit": {
"type": "streamableHttp",
"url": "https://checkdigit.mike-tusa.workers.dev/mcp"
}
}
}
Claude Desktop: open Settings > Connectors, choose "Add custom connector" and paste https://checkdigit.mike-tusa.workers.dev/mcp. Or, for clients that only support local (stdio) servers, use the mcp-remote bridge: npx mcp-remote https://checkdigit.mike-tusa.workers.dev/mcp.
VS Code uses a servers key instead of mcpServers.
The server.json file is the MCP Registry manifest for this server.
Run your own copy
Requires Node.js 22+ and a Cloudflare account.
npm install
npx wrangler@4 dev # local dev server
wrangler.toml is a template: create your own KV namespaces / D1 databases / rate-limit namespaces and replace the <PLACEHOLDER> values before npx wrangler@4 deploy. Any secrets the Worker reads go in wrangler secret put (or .dev.vars locally), never in the repo.
License
MIT (c) Digital Promo Hub. See LICENSE.
CheckDigit MCP questions
What types of codes can CheckDigit validate?
The server performs format checks for IBAN, BIC, EU VAT, GTIN/EAN/UPC, and ISBN.
How do I use CheckDigit with Claude Desktop?
You can add it by going to Settings > Connectors, selecting 'Add custom connector', and pasting the server URL.
Can I run my own instance of the server?
Yes, you can run your own copy using Node.js 22+ and a Cloudflare account.