# Business Phone and Email from a GSTIN: Contact API | FastKYC

> Fetch the mobile number and email address registered against a GST number, giving you verified contact details for a business you are onboarding.

Source: https://www.fastkyc.com/apis/gst-to-contact-details/

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[Identity](/apis/identity/)

# Contact Details by GST API

Fetch the mobile number and email address registered against a GST number, giving you verified contact details for a business you are onboarding.

[Book a Demo](/book-demo/)

Overview

## What the Contact Details by GST API does

Contact Details by GST returns the mobile number and email address registered against a GSTIN.

These are the contact details the business gave the tax authority, which makes them more reliable than whatever appears on a website or was typed into your form. For merchant verification that difference matters.

## Built for

[Marketplaces & E-commerce](/industries/marketplaces/)[Logistics & Mobility](/industries/logistics/)

Use cases

## Where teams use the Contact Details by GST API

-   Obtaining verified contact details for a merchant
    
-   Cross-checking declared contacts against GST records
    
-   Reaching a business through registered channels
    
-   Detecting mismatches in merchant onboarding
    

## Frequently Asked Questions (FAQs)

## Related APIs

-   [GST Verification APIVerify a GST number and retrieve the registered business name, address, status and registration details from GST records.](/apis/gst-verification/)
-   [Email Check APIVerify an email address is legitimate and deliverable, filtering out disposable, invalid and undeliverable addresses before they enter your database.](/apis/email-check/)
-   [Fastag Lookup APIRetrieve FASTag information for a vehicle, including tag status and the details registered against it, for vehicle verification and fleet onboarding.](/apis/fastag-lookup/)
-   [Mobile to Address APIRetrieve address details linked to a mobile number, aggregated from telecom, utility and financial data sources, to prefill and verify customer addresses.](/apis/mobile-to-address/)

## Guides on the Contact Details by GST API

-   [GuideGST Verification Online: How to Verify a GST NumberVerify a GSTIN online to confirm a business is registered and compliant: what the 15 characters mean, how to check it on the portal, and how to automate it.](/blog/how-to-verify-gst-online/)

## Start verifying with the Contact Details by GST API

Book a walkthrough and we will show the call, the response and how it fits your onboarding flow.

-   One API key for every check
-   Verified against official Indian records
-   Built for onboarding at scale

[Book a Demo](/book-demo/)[Browse All APIs](/apis/)