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

# Introduction

> Crypto payment infrastructure for online merchants

# Settlx API

Settlx is a cryptocurrency payment gateway built for developers. Accept payments across multiple blockchains, and receive automatic settlement into your preferred token and chain. Settlx handles address generation, blockchain monitoring, confirmation tracking, currency conversion, and fund transfer — your backend just creates an invoice and handles webhooks.

```
Base URL: https://api.settlx.io/api/v1
```

***

## How a payment works

<Steps>
  <Step title="Create an invoice">
    Your backend calls `POST /api/v1/invoices`. Settlx generates a unique deposit address and returns a QR code and exact crypto amount.
  </Step>

  <Step title="Customer pays">
    The customer sends the exact amount to the deposit address from their wallet. Settlx monitors the blockchain in real time.
  </Step>

  <Step title="Payment confirmed">
    Once the transaction reaches the required number of confirmations, Settlx fires an `invoice.confirmed` webhook to your backend, then triggers settlement.
  </Step>

  <Step title="Settlement">
    Settlx converts and transfers the funds to your wallet. When the transfer completes, an `invoice.settled` webhook fires — this is when you fulfill the order.
  </Step>
</Steps>

***

## Supported chains

Settlx supports EVM-compatible chains (Ethereum, Polygon, BNB Smart Chain), Solana, Tron, and Bitcoin.

For the full list of supported chains, tokens, and contract addresses, call `GET /api/v1/tokens` — no API key required.

***

## Start building

<CardGroup cols={2}>
  <Card title="Authentication" icon="key" href="/authentication">
    Get your API key and authenticate your first request.
  </Card>

  <Card title="Create an Invoice" icon="file-invoice" href="/api-reference/invoices/create">
    The starting point for any payment flow.
  </Card>
</CardGroup>

<Card title="Webhooks" icon="webhook" href="/webhooks/overview">
  Understand the events Settlx sends and how to verify them.
</Card>