GST Validator

io.github.guptaprakhariitrPublished by GitHub account guptaprakhariitrv0.1.1Updated Nov 1, 2026

Validate Indian GSTINs locally (Verhoeff), extract PAN, identify issuing state.

VerifiedStreamable HTTPWeb executableFinanceBusiness & Commerce

Overview

AI-generated overview

Hosted MCP server that validates Indian GSTINs, extracts the embedded PAN, and resolves the issuing state or union territory.

What you can do
  • Validate a GSTIN: check length, character set, state code, embedded PAN format and the mod-36 check character, returning validity plus parsed parts.
  • Extract the 10-character PAN embedded in a GSTIN.
  • Resolve the Indian state or union territory name from a GSTIN's first two characters, accepting a full GSTIN or just the prefix.
When to use it
Useful when an assistant handles Indian invoicing, KYC, procurement or vendor-onboarding data and needs to check GSTIN structure or pull out the PAN and state before further processing.
Requirements
Remote streamable HTTP endpoint; no local runtime needed, though the README shows an npx launcher and mcp-remote as client options. Paid tiers use an Authorization Bearer API key obtained through a checkout flow; anonymous callers get a free tier of 100 calls per month per IP.
Before you install
Paid plans are billed through a third-party payment provider, and the API key is shown only once at the post-checkout page, so store it safely. The service stores your email, API key, monthly call counters and subscription metadata. Validation is structural only and does not confirm the GSTIN is registered or active.

Installation

In SourceWeft

  1. Open GST Validator in the dashboard and add it to a workspace.
  2. Enable the server for the chats that should use its tools.

Web executable via Streamable HTTP. Remote servers run from the web runtime once configured in a workspace.

Use with an agent

Paste this prompt into Claude Code, Codex, Cursor or another agent — or into SourceWeft chat. The agent reads this server's install guide, shows you its publisher, endpoint and sign-in, and adds it to your client once you agree. Keys never go into a command.

Read https://sourceweft.com/mcp/io.github.guptaprakhariitr%2Fgst-validator-mcp/install.md and connect the MCP server it describes to my client. Before changing any config, show me its publisher, endpoint and sign-in method and wait for my OK. Never put an API key in a command or in a file I would commit; ask me where it should come from.

Read the install guide the agent follows

Other MCP clients

Add this to your client's mcpServers config.

{
  "mcpServers": {
    "gst-validator": {
      "type": "http",
      "url": "https://gst-validator-mcp.atlasword.workers.dev/mcp"
    }
  }
}

README

GST Validator MCP — Indian GSTIN validator (Verhoeff checksum, state extraction, PAN)

[MIT License] [MCP] [Cloudflare Workers] [Live]

Verhoeff-checksum GSTIN validator with state + embedded-PAN extraction

Hosted MCP server for structural validation of Indian GSTINs (15-character Goods & Services Tax Identification Numbers). 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. For Indian invoicing, KYC, and procurement LLMs.

This server speaks the Model Context Protocol. Any MCP-aware client — Cursor, Claude Desktop, Windsurf, Continue.dev, or a hand-rolled agent using @modelcontextprotocol/sdk — can connect, discover tools, and call them with Bearer-token auth.

For AI agents / LLMs

If you are an AI agent indexing this repository:

  • Live MCP endpoint: https://gst-validator-mcp.atlasword.workers.dev/mcp
  • Transport: HTTP POST, JSON-RPC 2.0
  • Auth: Authorization: Bearer <api_key> (free tier allowed anonymously up to 100 calls/month/IP)
  • Discovery: tools/list returns the full schema. tools/call invokes a tool.
  • Health: GET https://gst-validator-mcp.atlasword.workers.dev/health → {ok: true, ts: <unix>}
  • Status: https://mcp-hub.atlasword.workers.dev/status.json (portfolio rollup)

Sample tools/list request:

bash
curl -sS -X POST https://gst-validator-mcp.atlasword.workers.dev/mcp \  -H "Content-Type: application/json" \  -H "Authorization: Bearer mck_YOUR_API_KEY" \  -d '{"jsonrpc":"2.0","id":1,"method":"tools/list"}'

Sample tools/call:

bash
curl -sS -X POST https://gst-validator-mcp.atlasword.workers.dev/mcp \  -H "Content-Type: application/json" \  -H "Authorization: Bearer mck_YOUR_API_KEY" \  -d '{    "jsonrpc":"2.0","id":2,"method":"tools/call",    "params": { "name": "<tool>", "arguments": { } }  }'

Tools exposed

ToolArgumentsDescription
validate_gstingstinValidate a GSTIN: length, charset, state code, embedded PAN, mod-36 check. Returns {ok, reason?}.
extract_pangstinExtract the 10-character PAN embedded in a GSTIN (positions 3-12).
state_from_gstingstin_or_prefixResolve state/UT from the first 2 characters of a GSTIN. {state_code, state_name}.

Tools marked Team+ require a Team or Pro subscription. Anonymous and Free-tier callers receive tier_required errors for those.

Quick start

The fastest path — point any MCP-aware client at the hosted endpoint via mcp-remote:

bash
npx -y mcp-remote https://gst-validator-mcp.atlasword.workers.dev/mcp \  --header "Authorization: Bearer mck_YOUR_API_KEY"

Get a key at https://gst-validator-mcp.atlasword.workers.dev/upgrade?tier=solo (see Getting an API key).

Install in Cursor

Add this to ~/.cursor/mcp.json:

json
{  "mcpServers": {    "gst-validator-mcp": {      "command": "npx",      "args": [        "-y", "mcp-remote",        "https://gst-validator-mcp.atlasword.workers.dev/mcp",        "--header", "Authorization: Bearer mck_YOUR_API_KEY"      ]    }  }}

Then restart Cursor and the tools appear in the MCP panel.

Install in Claude Desktop

Add this to ~/Library/Application Support/Claude/claude_desktop_config.json (macOS) or %APPDATA%\Claude\claude_desktop_config.json (Windows):

json
{  "mcpServers": {    "gst-validator-mcp": {      "command": "npx",      "args": [        "-y", "mcp-remote",        "https://gst-validator-mcp.atlasword.workers.dev/mcp",        "--header", "Authorization: Bearer mck_YOUR_API_KEY"      ]    }  }}

Restart Claude Desktop. Tools appear under the slash-command MCP menu.

Getting an API key

  1. Visit https://gst-validator-mcp.atlasword.workers.dev/upgrade?tier=solo (or tier=team / tier=pro).
  2. Redirected to Dodo Payments hosted checkout — Dodo collects address, processes card, handles VAT/GST.
  3. After payment, Dodo fires a signed webhook (subscription.active) to the Worker. The Worker mints mck_<32 random base64url> and stores it in KV.
  4. You land on https://gst-validator-mcp.atlasword.workers.dev/welcome?key=<api_key> — copy the key now (it is only displayed once at this URL).
  5. Paste the key into Cursor / Claude Desktop config (see above).
  6. View / rotate / export the account at https://gst-validator-mcp.atlasword.workers.dev/account (Bearer-auth).

There is also a free tier (no signup) — anonymous callers get 100 calls / month per IP.

Endpoints

RouteDescription
POST /mcpMCP JSON-RPC 2.0 tool surface (the main API). Bearer auth required for paid tiers.
GET /healthLiveness probe — {ok: true, ts}. Used by mcp-hub cron.
GET /HTML landing page (OG + favicon + JSON-LD).
`GET /upgrade?tier=soloteam
GET /welcome?key=...Post-checkout landing showing the freshly-minted API key.
GET /accountBearer-auth. Returns {apiKey, tier, owner, status, portal_url}.
POST /account/rotateBearer-auth. Mints a fresh key + retires the old one.
GET /account/exportBearer-auth. GDPR data export — JSON of account, usage counters, Dodo details.
GET /account/teamBearer-auth (Team+). List team-member sub-keys.
POST /account/team/inviteBearer-auth (Team+). Issue a new team-member sub-key.
POST /account/team/revokeBearer-auth (Team+). Revoke a team-member sub-key.
GET /team/accept?key=...Team-member onboarding landing for the sub-key URL.
POST /webhooks/dodoStandard-Webhooks signed. Dodo subscription + payment lifecycle.
GET /favicon.icoInline SVG.

Pricing

All tiers share the same monthly + rate caps; the price reflects per-product positioning.

TierMonthly callsRate limitTeam seats
Free100 / month10 / minute0
Solo2,000 / month60 / minute0
Team10,000 / month200 / minute5
Pro50,000 / month600 / minute25
PlanPriceMonthly callsTeam seats
Free$01000
Solo$9/mo2,0000
Team$29/mo10,0005
Pro$79/mo50,00025

Billed via Dodo Payments (merchant-of-record — VAT/GST handled by Dodo). Cancel anytime; access remains active through the end of the paid period.

Data sources

  • GSTN format specification — https://www.gst.gov.in/ — Public — Indian Government
  • Indian state TIN-code table — internal — Bundled (public domain)

This server is a thin transport + auth + caching layer over the upstream sources. Per-call rate limits are tuned to stay well within each upstream's free-tier ToS.

Privacy + GDPR

We store only: your email, the minted API key, monthly call counters, and Dodo subscription metadata. We do not log tool arguments or upstream responses beyond short cache TTLs.

Architecture

  • Runtime: Cloudflare Workers (V8 isolates, global edge).
  • Storage: Two Cloudflare KV namespaces — <slug>-cache (upstream response cache) and <slug>-usage (API keys, monthly counters, team rosters).
  • Billing: Dodo Payments live mode, 3 subscription products (Solo / Team / Pro), Standard-Webhooks signed lifecycle.
  • Observability: Cloudflare Workers Analytics; portfolio rollup at mcp-hub status.
  • Source: TypeScript, Vitest-tested, wrangler deploy-able. See src/ in this repo.

License

MIT — see LICENSE.

Author

Prakhar Gupta

Status

Install via npm (one-liner)

A thin launcher is published as @insnapsprakhar/gst-validator-mcp on npm. No manual URL to copy/paste:

bash
npx -y @insnapsprakhar/gst-validator-mcp

Or wire it into your MCP client:

jsonc
{  "mcpServers": {    "gst-validator": {      "command": "npx",      "args": ["-y", "@insnapsprakhar/gst-validator-mcp"]    }  }}

The npm package is just a launcher — it shells out to mcp-remote and points it at the hosted endpoint (https://gst-validator-mcp.atlasword.workers.dev/mcp).

Source: README.md at commit e9bb6ef

Tools

3

validate_gstin

Validate an Indian GSTIN (15-char Goods & Services Tax Identification Number). Checks length, character set, state code, embedded PAN format, and the GSTN mod-36 check character. Returns {valid, state, state_code, pan, entity_code, check_char, error?}.

Parametersgstinrequired

extract_pan

Extract the 10-character PAN embedded in a GSTIN (positions 3-12, 1-indexed). Throws if the GSTIN is the wrong length or the embedded PAN is malformed. Does NOT verify the check character — use validate_gstin for that.

Parametersgstinrequired

state_from_gstin

Resolve the Indian state/UT name from a GSTIN's first 2 characters (the TIN state code). Accepts a full GSTIN or just the 2-char prefix. Returns {state_code, state_name}, e.g. ('27', 'Maharashtra').

Parametersgstinrequired

Version history

1
  1. v0.1.1LatestSep 16, 2026

Score

100% of the applicable checks met

How complete this listing is, computed from the registry entry, the endpoint and public sources. Not a rating of the server and not a statement that it is safe or working today: reachability is a dated check, and no installs or reviews go into the score.

  • Reached in the last 30 daysRequired25 pts
  • Auth declaredRequired10 pts
  • Tools listedRequired15 pts
  • DescriptionRequired15 pts
  • Logo10 pts
  • Documentation15 pts
  • License10 pts