> ## Documentation Index
> Fetch the complete documentation index at: https://docs.txncheck.com/llms.txt
> Use this file to discover all available pages before exploring further.

# Introduction

> Welcome to the TxnCheck API documentation

# TxnCheck API

TxnCheck is a comprehensive identity verification and fraud prevention platform for the Indian market. Our API enables businesses to verify customer identities, validate UPI addresses, and detect potential fraud in real-time.

<CardGroup cols={2}>
  <Card title="Quick Start" icon="rocket" href="/quickstart">
    Get up and running with your first API call in minutes
  </Card>

  <Card title="Authentication" icon="key" href="/authentication">
    Learn how to authenticate your API requests
  </Card>

  <Card title="Webhooks" icon="webhook" href="/guides/webhooks">
    Receive real-time notifications about verification results
  </Card>

  <Card title="API Reference" icon="code" href="/api-reference/overview">
    Explore all available endpoints
  </Card>
</CardGroup>

## Available Services

<AccordionGroup>
  <Accordion title="UPI by Mobile">
    Retrieve and validate all UPI IDs (VPAs) linked to a mobile number without OTP verification. Helps businesses verify if the handle is active and linked to the correct user.

    **Use cases:**

    * Customer onboarding verification
    * Payment address validation
    * Fraud prevention checks
  </Accordion>

  <Accordion title="KYC by Mobile">
    Perform KYC verification using only the mobile number. Fetches identity-linked details such as name, date of birth, PAN, and masked Aadhaar from authorized sources.

    **Use cases:**

    * Digital customer onboarding
    * Identity verification
    * Compliance checks
  </Accordion>

  <Accordion title="VPA Chargeback Check">
    Check VPA addresses against a comprehensive blocklist of flagged accounts. Identify potentially fraudulent UPI addresses before processing transactions.

    **Use cases:**

    * Pre-transaction fraud screening
    * Risk assessment
    * Chargeback prevention
  </Accordion>

  <Accordion title="Full Check">
    Comprehensive verification combining UPI lookup, KYC verification, and chargeback check in a single request. Get complete customer intelligence in one API call.

    **Use cases:**

    * Complete customer verification
    * High-value transaction screening
    * Enhanced due diligence
  </Accordion>

  <Accordion title="Bulk VPA Check">
    Check up to 100 VPA addresses against the blocklist in a single request. Ideal for batch processing and periodic fraud screening.

    **Use cases:**

    * Batch customer screening
    * Periodic fraud audits
    * Large-scale verification
  </Accordion>
</AccordionGroup>

## Base URL

All API requests are made to:

```
https://api.txncheck.in/api/v1
```

## Processing Modes

TxnCheck API supports two processing modes:

<CardGroup cols={2}>
  <Card title="Async Mode (Default)" icon="clock">
    Request is queued, results delivered via webhooks or polling. Best for high throughput and background processing.
  </Card>

  <Card title="Sync Mode" icon="bolt">
    Wait for result directly in the response. Set `async: false` in your request. Timeout: 30 seconds.
  </Card>
</CardGroup>

### Async Mode Flow (Default)

```mermaid theme={null}
sequenceDiagram
    participant Client
    participant API as TxnCheck API
    participant Webhook as Your Webhook

    Client->>API: POST /upi-by-mobile
    API-->>Client: 202 Accepted (requestId)
    Note over API: Processing...
    API->>Webhook: POST (verification result)
    Webhook-->>API: 200 OK
    Client->>API: GET /requests/{requestId}
    API-->>Client: 200 OK (result data)
```

### Sync Mode Flow

```mermaid theme={null}
sequenceDiagram
    participant Client
    participant API as TxnCheck API

    Client->>API: POST /upi-by-mobile {"async": false}
    Note over API: Processing...
    API-->>Client: 200 OK (result data)
```

<Note>
  **When to use Sync mode:** Real-time decision making where you need the result immediately (e.g., checkout flows).

  **When to use Async mode:** Background verification, batch processing, or when webhook delivery is preferred.
</Note>

## Request Statuses

| Status       | Description                                     |
| ------------ | ----------------------------------------------- |
| `QUEUED`     | Request received and waiting for processing     |
| `PROCESSING` | Request is being processed                      |
| `COMPLETED`  | Request completed successfully                  |
| `FAILED`     | Request failed (check error details)            |
| `PARTIAL`    | Request partially completed (some steps failed) |

## Need Help?

<CardGroup cols={2}>
  <Card title="API Reference" icon="book" href="/api-reference/overview">
    Detailed endpoint documentation
  </Card>

  <Card title="Support" icon="headset" href="https://app.txncheck.com">
    Contact our support team
  </Card>
</CardGroup>