GST Validator — hosted on Cloudflare Workers (HTTP + npm stdio)

What is GST Validator?

GST Validator is a hosted MCP server that performs structural validation of Indian GSTINs (15‑character Goods & Services Tax Identification Numbers). It verifies length, character set, state code, embedded PAN format, and the GSTN mod‑36 (Verhoeff) check digit, extracts the embedded PAN, and resolves the state from the TIN prefix. This server is designed for AI agents and LLMs handling Indian invoicing, KYC, and procurement tasks.

How to use GST Validator?

Point any MCP-aware client (Cursor, Claude Desktop, Windsurf, Continue.dev) at the hosted endpoint via npx mcp-remote, or use the npm launcher @insnapsprakhar/gst-validator-mcp. Obtain a free API key (100 calls/month per IP) from the upgrade page, then configure your client with the Bearer token. Tools are discovered automatically via tools/list and invoked via tools/call.

Key features of GST Validator

• Verhoeff checksum validation for GSTIN integrity
• Extracts the 10‑character PAN embedded in a GSTIN
• Resolves Indian state/UT from the GSTIN prefix
• Hosted on Cloudflare Workers with global edge availability
• Free tier (100 calls/month) and paid tiers with higher limits
• Bearer‑token authentication and team‑member sub‑keys

Use cases of GST Validator

• Validate GSTINs in automated invoicing or billing workflows
• Extract PAN from GSTIN for KYC checks during vendor onboarding
• Resolve state codes for tax compliance in procurement systems

FAQ from GST Validator

What does GST Validator do? Does it verify against the government database?

GST Validator performs structural validation of the GSTIN format—length, charset, state code, embedded PAN, and the Verhoeff check digit. It does not query the government GST portal for real‑time validation.

What are the runtime dependencies for the client?

No runtime dependencies beyond any Node.js environment that can run npx. The server is hosted on Cloudflare Workers; the client only needs network access and a Bearer token.

Where does my data go? Is it logged?

Data such as tool arguments or upstream responses are not logged beyond short‑lived cache TTLs. Only your email, API key, monthly call counters, and subscription metadata are stored in Cloudflare KV.

How do I authenticate and what transport is used?

Authentication is via HTTP Bearer token (Authorization: Bearer <api_key>). The server uses HTTP POST with JSON‑RPC 2.0 over the MCP protocol. Free tier callers with no API key are allowed up to 100 calls/month per IP.

What are the rate limits and pricing tiers?

Free tier: 100 calls/month, 10 calls/minute. Solo: 2,000 calls/month, 60/minute, $9/mo. Team: 10,000/month, 200/minute, 5 seats, $29/mo. Pro: 50,000/month, 600/minute, 25 seats, $79/mo.