# Find a GSTIN by Mobile Number: Mobile to GST API | FastKYC

> Find GST identification numbers linked to a mobile number, validated across government and financial registration databases.

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

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[Finance APIs](/apis/finance/)

# Mobile to GST API

Find GST identification numbers linked to a mobile number, validated across government and financial registration databases.

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

Category

[Finance APIs](/apis/finance/)

Built for

-   [Lending & NBFC](/industries/lending/)
-   [Fintech & Payments](/industries/fintech-payments/)
-   [Marketplaces & E-commerce](/industries/marketplaces/)
-   [Telecom](/industries/telecom/)
-   [Logistics & Mobility](/industries/logistics/)

## What the Mobile to GST API does

Mobile to GST resolves a mobile number to any GSTINs registered against it, checking government and financial registration records.

For merchant onboarding this removes a form field that customers routinely get wrong. It also surfaces registrations a merchant did not mention, which is worth knowing before you set a credit limit.

## Where teams use the Mobile to GST API

1.  Onboarding merchants without asking for a GSTIN
    
2.  Discovering undisclosed business registrations
    
3.  Pre-filling business details from a phone number
    
4.  Cross-checking a declared GSTIN against the merchant's number
    

## Frequently Asked Questions (FAQs)

What if no GSTIN is found?

The number may not be registered against any GST record, or the business may not be registered at all. Treat it as inconclusive.

Can one number return several GSTINs?

Yes, where the business operates in multiple states, since GST registration is state-wise.

How do I verify the GSTIN itself?

Pass it to GST Verification or GST Advanced for registration status and compliance detail.

## Related APIs

-   [Mobile to RC API Find the vehicle registration numbers linked to a mobile number, validated against transport and insurance databases, for vehicle loans and insurance.](/apis/mobile-to-rc/)
-   [Mobile to MSME API Find the MSME Udyam registration linked to a mobile number from official government and business registry sources, without asking for the Udyam number.](/apis/mobile-to-msme/)
-   [Mobile to PAN API Find the PAN linked to a mobile number and name, validated against trusted telecom and financial sources, so customers don't have to type their PAN.](/apis/mobile-to-pan/)
-   [Mobile to UAN API Find the Universal Account Numbers linked to an Indian mobile number, so an employment check can start from a phone number alone.](/apis/mobile-to-uan/)

## Start verifying with the Mobile to GST API

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

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

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