OpenSea API

OpenSea API

Query NFT data, trade on the Seaport marketplace, and swap ERC20 tokens across Ethereum, Base, Arbitrum, Optimism, Polygon, and more.

Quick start

1. Set OPENSEA_API_KEY in your environment
2. Run helper scripts in scripts/ for common operations
3. Use the MCP server for token swaps and advanced queries

export OPENSEA_API_KEY="your-api-key"

# Token swap: ETH to token
./scripts/opensea-swap.sh 0xTokenAddress 0.1 0xYourWallet 0xYourKey base

# Token swap: Token to token (specify from_token as last arg)
./scripts/opensea-swap.sh 0xToToken 100 0xYourWallet 0xYourKey base 0xFromToken

# Get collection info
./scripts/opensea-collection.sh boredapeyachtclub

# Get NFT details
./scripts/opensea-nft.sh ethereum 0xbc4ca0eda7647a8ab7c2061c2e118a18a936f13d 1234

# Get best listing price for an NFT
./scripts/opensea-best-listing.sh boredapeyachtclub 1234

Task guide

Token swaps

OpenSea's API includes a cross-chain DEX aggregator for swapping ERC20 tokens with optimal routing across all supported chains.

Reading NFT data

Marketplace queries

Marketplace actions (POST)

Events and monitoring

Generic requests

Buy/Sell workflows

Buying an NFT

1. Find the NFT and check its listing:

   ./scripts/opensea-best-listing.sh cool-cats-nft 1234
   

2. Get the order hash from the response, then get fulfillment data:

   ./scripts/opensea-fulfill-listing.sh ethereum 0x_order_hash 0x_your_wallet
   

3. The response contains transaction data to execute on-chain

Selling an NFT (accepting an offer)

1. Check offers on your NFT:

   ./scripts/opensea-best-offer.sh cool-cats-nft 1234
   

2. Get fulfillment data for the offer:

   ./scripts/opensea-fulfill-offer.sh ethereum 0x_offer_hash 0x_your_wallet 0x_nft_contract 1234
   

3. Execute the returned transaction data

Creating listings/offers

Creating new listings and offers requires wallet signatures. Use opensea-post.sh with the Seaport order structure - see references/marketplace-api.md for full details.

Scripts reference

NFT & Collection Scripts

Marketplace Scripts

Token Swap Scripts

Monitoring Scripts

Supported chains

ethereum, matic, arbitrum, optimism, base, avalanche, klaytn, zora, blast, sepolia

References

• references/rest-api.md - REST endpoint families and pagination
• references/marketplace-api.md - Buy/sell workflows and Seaport details
• references/stream-api.md - WebSocket event streaming
• references/seaport.md - Seaport protocol and NFT purchase execution
• references/token-swaps.md - Token swap workflows via MCP

OpenSea MCP Server

An official OpenSea MCP server provides direct LLM integration for token swaps and NFT operations. When enabled, Claude can execute swaps, query token data, and interact with NFT marketplaces directly.

Setup:

1. Go to the OpenSea Developer Portal and verify your email
2. Generate a new API key for REST API access
3. Generate a separate MCP token for the MCP server

Add to your MCP config:

{
  "mcpServers": {
    "opensea": {
      "url": "https://mcp.opensea.io/mcp",
      "headers": {
        "Authorization": "Bearer YOUR_MCP_TOKEN"
      }
    }
  }
}

Or use the inline token format: https://mcp.opensea.io/YOUR_MCP_TOKEN/mcp

Token Swap Tools

NFT Tools

Profile & Utility Tools

Token Swaps via MCP

OpenSea MCP supports ERC20 token swaps across supported DEXes - not just NFTs!

Get Swap Quote

mcporter call opensea.get_token_swap_quote --args '{
  "fromContractAddress": "0x0000000000000000000000000000000000000000",
  "fromChain": "base",
  "toContractAddress": "0xb695559b26bb2c9703ef1935c37aeae9526bab07",
  "toChain": "base",
  "fromQuantity": "0.02",
  "address": "0xYourWalletAddress"
}'

Parameters:

• fromContractAddress: Token to swap from (use 0x0000...0000 for native ETH)
• toContractAddress: Token to swap to
• fromChain / toChain: Chain identifiers
• fromQuantity: Amount in human-readable units (e.g., "0.02" for 0.02 ETH)
• address: Your wallet address

Response includes:

• swapQuote: Price info, fees, slippage impact
• swap.actions[0].transactionSubmissionData: Ready-to-use calldata

Execute the Swap

import { createWalletClient, http } from 'viem';
import { privateKeyToAccount } from 'viem/accounts';
import { base } from 'viem/chains';

// Extract from swap quote response
const txData = response.swap.actions[0].transactionSubmissionData;

const wallet = createWalletClient({ 
  account: privateKeyToAccount(PRIVATE_KEY), 
  chain: base, 
  transport: http() 
});

const hash = await wallet.sendTransaction({
  to: txData.to,
  data: txData.data,
  value: BigInt(txData.value)
});

Check Token Balances

mcporter call opensea.get_token_balances --args '{
  "address": "0xYourWallet",
  "chains": ["base", "ethereum"]
}'

Generating a wallet

To execute swaps or buy NFTs, you need an Ethereum wallet (private key + address).

Using Node.js

import crypto from 'crypto';
import { privateKeyToAccount } from 'viem/accounts';

const privateKey = '0x' + crypto.randomBytes(32).toString('hex');
const account = privateKeyToAccount(privateKey);

console.log('Private Key:', privateKey);
console.log('Address:', account.address);

Using OpenSSL

# Generate private key
PRIVATE_KEY="0x$(openssl rand -hex 32)"
echo "Private Key: $PRIVATE_KEY"

# Derive address (requires node + viem)
node --input-type=module -e "
import { privateKeyToAccount } from 'viem/accounts';
console.log('Address:', privateKeyToAccount('$PRIVATE_KEY').address);
"

Using cast (Foundry)

cast wallet new

Important: Store private keys securely. Never commit them to git or share publicly.

Requirements

• OPENSEA_API_KEY environment variable (for REST API scripts)
• OPENSEA_MCP_TOKEN environment variable (for MCP server, separate from API key)
• curl for REST calls
• websocat (optional) for Stream API
• jq (recommended) for parsing JSON responses

Get both credentials at opensea.io/settings/developer.