A free, local Python tool that protects your B2B invoicing and GST tax compliance. It validates 15-character Indian GSTIN tax IDs completely offline using the official GST Council Modulo-36 checksum algorithm, state code tables, and entity PAN regex—quarantining invalid tax IDs before you generate invoices or submit GSTR-1 returns.
Single GSTIN string or B2B customer CSV with GSTIN column.
Local Python script validates 15-char structure, state code, PAN regex, and computes Modulo-36 check digit.
validated_gstin_ledger.csv, invalid_gstins_quarantined.csv, and summary stats.
Setup scope covers installation on customer-controlled infrastructure, configuration of authorised integrations, functional testing and handover.
Hosting, third-party charges and ongoing support are excluded unless separately agreed. Free workflows must never run on Sanocea-hosted infrastructure.
B2B buyers frequently enter mistyped or fake GST numbers at checkout. When you file GSTR-1 returns, mismatched tax IDs cause input tax credit rejections and expensive accountant reconciliation fees.
Invalid GSTINs trigger tax portal filing errors and buyer disputes when your customers cannot claim input tax credit (ITC) on their business purchases.
Takes a list of customer GST numbers, tests them against the government Modulo-36 checksum algorithm and 15-character structure, and separates valid tax IDs from typos.
You catch GSTIN errors immediately upon checkout or bulk import, requesting corrected tax certificates before generating final tax invoices.
Shows how an invalid GST number with a typo in its checksum digit is caught offline.
customer_name,gstin
Acme Traders Surat,24AAACA1234A1Z5
Invalid Buyer Mumbai,27AAACA1234A1Z9customer_name,gstin,valid,failure_reason
Invalid Buyer Mumbai,27AAACA1234A1Z9,False,CHECKSUM_FAILED (Expected '5', got '9')Catches typographical errors before issuing tax invoices, preventing B2B input tax credit rejections.
Technical Setup Guidance: 100% offline compute. Does not connect to the Internet or make external API calls.
Takes 2 minutes. Download the free script and run it directly with Python.
Every deliverable is clean, self-contained, and ready for immediate deployment. You receive the complete files, configuration templates, setup guides, and automated tests.
| File Name | Deliverable Description |
|---|---|
validate.py | Standalone Python 3.8+ offline GSTIN validation script and module |
README.md | Step-by-step usage guide, CLI examples, and algorithm explanation |
SETUP.md | Quickstart instructions for local setup and testing |
COSTS.md | Detailed recurring cost disclosure (₹0 ongoing fees) |
LICENSING.md | Sanocea Open Workflow License (MIT Compatible, free commercial self-hosting) |
tests/test_gstin_validator.py | Automated test suite verifying valid, invalid, and edge-case GSTINs |
For technical teams or developers assisting your business, below is the visual execution architecture and automated verification breakdown:
100% offline verification using deterministic Modulo-36 arithmetic. Distinguishes structural/checksum validity from live GST portal active taxpayer registration without requiring paid GSP APIs.
Validates state code, PAN format, entity number, and Z default character.
Calculates checksum according to GST Council specifications.
Runs completely offline without transmitting taxpayer information to external servers.
We believe in complete transparency. Review the documented technical boundaries and external service fee breakdown below prior to obtaining the package:
| Component | Estimated Cost | Details & Free Tier Allowances |
|---|---|---|
| GSTIN Validator Tool | ₹0 (Free to self-host) | Download full source code and self-host on your own machine |
| Optional Assisted Setup | ₹500 one-time | Installation on customer-controlled infrastructure, CLI integration, and handover |
| API & Recurring Fees | ₹0 Forever | Runs 100% offline with zero external network requests |
Receive the complete distributable archive containing validate.py, step-by-step setup guides, mock fixtures, and automated test suites.
Setup scope covers installation on customer-controlled infrastructure, configuration of authorised integrations, functional testing and handover.
Hosting, third-party charges and ongoing support are excluded unless separately agreed. Free workflows must never run on Sanocea-hosted infrastructure.
No. It uses purely offline algorithmic validation based on official Indian GST Council Modulo-36 checksum standards with zero external API fees.
Yes. Because execution happens in pure Python standard library in-memory, it validates over 10,000 numbers in less than a second.
It validates length (15 characters), valid 2-digit state codes (01 to 38), alphanumeric PAN structure, standard 14th character ('Z'), and calculates the 15th checksum character.
How Indian B2B merchants validate buyer tax identification numbers offline, why GSTR-1 filings reject malformed GST numbers, and how mathematical algorithms prevent input credit losses.
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