Sei is a high-performance blockchain designed for decentralized finance (DeFi) applications. It offers fast transaction speeds, scalability, and a developer-friendly environment, making it an ideal platform for deploying DeFi applications and services.

The Sei API allows developers to interact with the Sei network through a collection of JSON-RPC methods. Given its compatibility with standard blockchain APIs, developers familiar with other blockchain JSON-RPC APIs will find working with Sei intuitive and straightforward.

Send Your First Request on Alchemy

Let’s use the viem package to create a Sei client connected to Alchemy and fetch the latest block number!

npm install --save viem

Create Client Connected to Alchemy

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import { createPublicClient, http } from "viem"; 
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import { sei } from "viem/chains";
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const client = createPublicClient({
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  chain: sei,
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  transport: http("https://sei-mainnet.g.alchemy.com/v2/YOUR_ALCHEMY_API_KEY"),
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});

Now that you’ve created a client connected to Alchemy, you can continue with some basics:

Get Latest Block Number

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const blockNumber = await client.getBlockNumber();
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console.log("Current block number:", blockNumber);

Get an Address Balance

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const balance = await client.getBalance({ address: "0xab5801a7d398351b8be11c439e05c5b3259aec9b" });
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console.log("Balance (SEI):", Number(balance) / 1e18);

Read Block Data

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const block = await client.getBlock({
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  blockNumber: blockNumber, // from previous example
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});
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console.log(block);

Fetch a Transaction by Hash

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const tx = await client.getTransaction({ hash: "0xYOUR_TX_HASH" });
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console.log(tx);

Fetch Transaction Receipt

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const receipt = await client.getTransactionReceipt({
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  hash: "0xYOUR_TX_HASH"
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});
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console.log(receipt);

Sei APIs

For the full list of Sei APIs, see the Sei API Endpoints.