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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

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How a payment works

1

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.
2

Customer pays

The customer sends the exact amount to the deposit address from their wallet. Settlx monitors the blockchain in real time.
3

Payment confirmed

Once the transaction reaches the required number of confirmations, Settlx fires an invoice.confirmed webhook to your backend, then triggers settlement.
4

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.

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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.

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Start building

Authentication

Get your API key and authenticate your first request.

Create an Invoice

The starting point for any payment flow.

Webhooks

Understand the events Settlx sends and how to verify them.