Solana Priority Fee API: Smart Transaction Fee Estimation

import { Transaction, SystemProgram, ComputeBudgetProgram } from "@solana/web3.js";
import bs58 from "bs58";

// 1. Build your transaction (without priority fee)
const transaction = new Transaction();
const transferIx = SystemProgram.transfer({
  fromPubkey: senderKeypair.publicKey,
  toPubkey: recipientPublicKey,
  lamports: 1000000, // 0.001 SOL
});
transaction.add(transferIx);

// 2. Set required fields and serialize
transaction.recentBlockhash = (await connection.getLatestBlockhash()).blockhash;
transaction.feePayer = senderKeypair.publicKey;
const serializedTx = bs58.encode(transaction.serialize());

// 3. Get priority fee estimate
const response = await fetch("https://mainnet.helius-rpc.com/?api-key=YOUR_API_KEY", {
  method: "POST",
  headers: { "Content-Type": "application/json" },
  body: JSON.stringify({
    jsonrpc: "2.0",
    id: "1",
    method: "getPriorityFeeEstimate",
    params: [{
      transaction: serializedTx,
      options: { 
        priorityLevel: "Medium",
        recommended: true 
      }
    }]
  })
});

const result = await response.json();
const priorityFee = result.result.priorityFeeEstimate;

// 4. Add priority fee and send
transaction.instructions = []; // Reset
transaction.add(ComputeBudgetProgram.setComputeUnitPrice({ microLamports: priorityFee }));
transaction.add(transferIx);
transaction.recentBlockhash = (await connection.getLatestBlockhash()).blockhash;
transaction.sign(senderKeypair);