Developer & Agent Ecosystem

GST Maker Developer Documentation & MCP Server

Connect your business apps, ecommerce systems, or AI agents (Claude Desktop, Cursor, ChatGPT, AutoGen) directly with GST Maker's Indian GST invoicing, calculation, and compliance engine.

OpenAPI 3.0 Spec

Machine-readable OpenAPI schema definition for all public and private endpoints.

openapi.json

Interactive API Docs

Test and inspect API endpoints live via Swagger UI.

Swagger Explorer

MCP Server (81 Tools)

Model Context Protocol server for Claude Desktop, Cursor, and agentic workflows.

MCP Endpoint

LLM Manifest

Standardized llms.txt protocol with agent instructions.

llms.txt Guide

Model Context Protocol (MCP) Server Setup

Anthropic MCP 2024-11-05 Compliant · 81 Tools Active

Connect GST Maker directly into Claude.ai Web (Connectors), Claude Desktop, Cursor IDE, or autonomous agent frameworks so AI models can validate Indian GSTINs, calculate CGST/SGST/IGST, search HSN codes, calculate composition taxes, evaluate ITC setoffs, check E-Way bill limits, and draft invoices in real-time.

Option 1: Claude.ai Web Custom Connector (1-Click)

In Claude.ai, open Settings > Connectors > Add custom connector and enter:

Name: GST Maker
Public URL: https://gstmaker.com/mcp
Authenticated Business URL: https://gstmaker.com/mcp?api_key=YOUR_API_KEY

Generate your API Key inside Profile Settings > Developer API Keys. Keys are encrypted via SHA-256 and multi-tenant isolated.

Option 2: Claude Desktop Integration (claude_desktop_config.json)

Add the following block to your Claude Desktop config file: 

{
  "mcpServers": {
    "gstmaker": {
      "command": "python",
      "args": ["-m", "core.mcp_server"],
      "env": {
        "GSTMAKER_API_KEY": "YOUR_API_KEY"
      }
    }
  }
}

Option 3: Cursor IDE Integration (.cursor/mcp.json) 

{
  "mcpServers": {
    "gstmaker": {
      "command": "python",
      "args": ["-m", "core.mcp_server"],
      "env": {
        "GSTMAKER_API_KEY": "YOUR_API_KEY"
      }
    }
  }
}

Option 4: Remote HTTP JSON-RPC (POST /mcp) 

curl -X POST https://gstmaker.com/mcp \
  -H "Content-Type: application/json" \
  -H "Authorization: Bearer YOUR_API_KEY" \
  -d '{
    "jsonrpc": "2.0",
    "id": 1,
    "method": "tools/call",
    "params": {
      "name": "calculate_gst",
      "arguments": {
        "taxable_amount": 50000,
        "gst_rate": 18,
        "is_interstate": false
      }
    }
  }'

Built-in Public MCP Tools List (30 Zero-Login Tools)

100% Free · No Login Required
Tool Name Input Arguments Action Description
lookup_hsn_code query: str Search Indian GST HSN/SAC codes, descriptions, and legal GST rates.
validate_gstin gstin: str Validates 15-digit GSTIN with Mod-36 checksum, state name, and PAN.
calculate_gst taxable_amount, gst_rate, is_interstate Computes exact CGST + SGST or IGST tax splits and final payable amount.
reverse_calculate_gst gross_amount, gst_rate Extracts base taxable amount and tax from a GST-inclusive gross total.
calculate_gstr_late_fee tax_liability, days_late, is_nil_return Computes Section 47 penalty and Section 50 interest on delayed GSTR filing.
generate_invoice_link description, hsn, rate, price, qty, business_name, customer_name Generates zero-login interactive guest invoice link ready for instant PDF download.
generate_quotation_link description, hsn, rate, price, qty, business_name, customer_name Generates zero-login interactive guest quotation/estimate link for clients.
generate_proforma_link description, hsn, rate, price, qty, business_name, customer_name Generates zero-login interactive guest proforma invoice link for advance payments.
calculate_composition_tax annual_turnover, category, is_special_category_state Evaluates threshold eligibility (₹1.5 Cr / ₹75L / ₹50L) & flat 1%/5%/6% tax liability.
check_eway_bill_limit state, consignment_value, is_interstate Checks state-wise intra-state (₹1 Lakh/₹50k) & inter-state E-way bill requirement.
calculate_itc_eligibility total_igst_credit, total_cgst_credit, total_sgst_credit, blocked_credit_amount, output liabilities Calculates eligible ITC, Sec 17(5) deductions, and Rule 88A tax offset sequence.
ai_recommend_hsn description: str AI-powered deduction of exact HSN/SAC code, classification, and tax slab for custom items.
ask_gst_advisor question, business_context AI GST Legal Advisor for CGST rules, ITC doubts, filing schedules, and compliance notices.
audit_invoice_text invoice_text: str Automated compliance audit against mandatory CGST Act Rule 46 requirements.
get_state_codes state_name (optional) Look up 2-digit Indian state GST jurisdiction codes (e.g. 07 Delhi, 27 Maharashtra).
search_blog_articles query (optional), limit Search published GST Maker blog articles, compliance tutorials, and tax invoicing guides.
get_blog_article_by_slug slug: str Fetch complete markdown text, reading time, author, and live link of any published blog article.

Authenticated Enterprise MCP Tools (51 Tools)

Requires an active GST Maker API Key. Full access to automate your private business operations via Claude Desktop or AI agents.

SHA-256 Encrypted · Tenant Isolated
Sales, Invoicing & Conversions

Search, fetch, draft, and convert Quotations and Proformas directly into official Tax Invoices. Access CA audit portals and manage recurring billing.

get_invoices, create_invoice, convert_quotation_to_invoice, convert_proforma_to_invoice, get_ca_portal_link...
Purchases, Expenses & Vendors

Record purchase bills, calculate input tax credit (ITC), manage vendor directory, and track company operational expenses.

get_purchase_bills, record_purchase_bill, get_vendors, create_vendor, record_expense...
Staff Attendance & Payroll

Inspect employee directory, retrieve month-wise day-by-day attendance history via get_staff_attendance_calendar, and calculate monthly payroll summaries.

get_staff_members, get_staff_attendance_calendar, get_staff_payroll_summary...
GSTR-1, Tax Liability & Plan Quotas

Compute GSTR-1 outward supplies (B2B Table 4, B2CL Table 5, B2CS Table 7, HSN Table 12, Docs Table 13), GSTR-3B tax matrix, and live subscription quotas via get_plan_usage_and_limits.

get_gstr1_sales_summary, get_gstr3b_tax_liability, get_plan_usage_and_limits...
Multi-Tenancy Isolation: All authenticated tool requests strictly isolate records by the owner's authenticated business account. Private records are completely protected and inaccessible to any unauthorized agent.

Guest Pre-filled Deep Links (For AI Agents & Bots)

AI agents, bots, and external CRMs can construct deep links to open the guest invoice, quotation, or proforma generators with pre-filled line items, HSN/SAC codes, and GST rates without requiring login:

1. Tax Invoice Generator:
https://gstmaker.com/try?hsn=847130&rate=18&desc=Laptops+and+Tablets&price=45000&qty=2
2. Quotation / Estimate Generator:
https://gstmaker.com/free-quotation-maker?desc=Website+Design+Services&rate=18&price=35000
3. Proforma Advance Bill Generator:
https://gstmaker.com/free-proforma-maker?desc=50%25+Advance+Payment&rate=18&price=25000

Supported Query Parameters:

desc / description: Item name
hsn / sac: HSN or SAC code
rate / gst: GST % (0, 5, 12, 18, 28)
price / amount: Unit price in INR
qty / quantity: Item quantity
unit: Unit (pcs, hrs, services)
business: Seller name
customer / client: Buyer name
is_interstate: true/false for IGST

API Authentication

All private dashboard and business management endpoints utilize standard JWT Bearer token authentication. Include your token in the request header:

Authorization: Bearer YOUR_ACCESS_TOKEN

REST Versioning & Deprecation Policy

Versioning Standard

Current API version is v1.0.0. We support path-based versioning (/v1/) and optional header negotiation via Accept-Version: 1.0 or X-API-Version: 1.0.

Sunset & Deprecation

We follow IETF RFC 8594 (Sunset Header). Deprecated endpoints will return Deprecation: @timestamp and Sunset: date headers at least 180 days before retirement.

Rate Limiting & RFC Response Headers

All API responses include standard IETF RateLimit headers so autonomous agents can self-throttle in real time:

RateLimit-Limit: 120
RateLimit-Remaining: 119
RateLimit-Reset: 60
RateLimit-Policy: "120;w=60"
Retry-After: 60 (returned on HTTP 429 Too Many Requests)