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. Preferred: Use the opensea CLI (@opensea/cli) for all queries and operations
3. Alternatively, use the shell scripts in scripts/ or the MCP server

export OPENSEA_API_KEY="your-api-key"

# Install the CLI globally (or use npx)
npm install -g @opensea/cli

# Get collection info
opensea collections get boredapeyachtclub

# Get floor price and volume stats
opensea collections stats boredapeyachtclub

# Get NFT details
opensea nfts get ethereum 0xbc4ca0eda7647a8ab7c2061c2e118a18a936f13d 1234

# Get best listings for a collection
opensea listings best boredapeyachtclub --limit 5

# Search across OpenSea
opensea search "cool cats"

# Get trending tokens
opensea tokens trending --limit 5

# Get a swap quote
opensea swaps quote \
  --from-chain base --from-address 0x0000000000000000000000000000000000000000 \
  --to-chain base --to-address 0xTokenAddress \
  --quantity 0.02 --address 0xYourWallet

Task guide

Recommended: Use the opensea CLI (@opensea/cli) as your primary tool. It covers all the operations below with a consistent interface, structured output, and built-in pagination. Install with npm install -g @opensea/cli or use npx @opensea/cli. The shell scripts in scripts/ remain available as alternatives.

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)

Search

Events and monitoring

Event types: sale, transfer, mint, listing, offer, trait_offer, collection_offer

Accounts

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.

OpenSea CLI (@opensea/cli)

The OpenSea CLI is the recommended way for AI agents to interact with OpenSea. It provides a consistent command-line interface and a programmatic TypeScript/JavaScript SDK.

Installation

# Install globally
npm install -g @opensea/cli

# Or use without installing
npx @opensea/cli collections get mfers

Authentication

# Set via environment variable (recommended)
export OPENSEA_API_KEY="your-api-key"
opensea collections get mfers

# Or pass inline
opensea --api-key your-api-key collections get mfers

CLI Commands

Global options: --api-key, --chain (default: ethereum), --format (json/table/toon), --base-url, --timeout, --verbose

Output Formats

• JSON (default): Structured output for agents and scripts
• Table: Human-readable tabular output (--format table)
• TOON: Token-Oriented Object Notation, uses ~40% fewer tokens than JSON — ideal for LLM/AI agent context windows (--format toon)

# JSON output (default)
opensea collections stats mfers

# Human-readable table
opensea --format table collections stats mfers

# Compact TOON format (best for AI agents)
opensea --format toon tokens trending --limit 5

Pagination

All list commands support cursor-based pagination with --limit and --next:

# First page
opensea collections list --limit 5

# Pass the "next" cursor from the response to get the next page
opensea collections list --limit 5 --next "LXBrPTEwMDA..."

Programmatic SDK

The CLI also exports a TypeScript/JavaScript SDK for use in scripts and applications:

import { OpenSeaCLI, OpenSeaAPIError } from "@opensea/cli"

const client = new OpenSeaCLI({ apiKey: process.env.OPENSEA_API_KEY })

const collection = await client.collections.get("mfers")
const { nfts } = await client.nfts.listByCollection("mfers", { limit: 5 })
const { listings } = await client.listings.best("mfers", { limit: 10 })
const { asset_events } = await client.events.byCollection("mfers", { eventType: "sale" })
const { tokens } = await client.tokens.trending({ chains: ["base"], limit: 5 })
const results = await client.search.query("mfers", { limit: 5 })

// Swap quote
const { quote, transactions } = await client.swaps.quote({
  fromChain: "base",
  fromAddress: "0x833589fcd6edb6e08f4c7c32d4f71b54bda02913",
  toChain: "base",
  toAddress: "0x3ec2156d4c0a9cbdab4a016633b7bcf6a8d68ea2",
  quantity: "1000000",
  address: "0xYourWalletAddress",
})

// Error handling
try {
  await client.collections.get("nonexistent")
} catch (error) {
  if (error instanceof OpenSeaAPIError) {
    console.error(error.statusCode)   // e.g. 404
    console.error(error.responseBody) // raw API response
    console.error(error.path)         // request path
  }
}

TOON Format for AI Agents

TOON (Token-Oriented Object Notation) is a compact serialization format that uses ~40% fewer tokens than JSON, making it ideal for piping CLI output into LLM context windows:

opensea --format toon tokens trending --limit 3

Example output:

tokens[3]{name,symbol,chain,market_cap,price_usd}:
  Ethereum,ETH,ethereum,250000000000,2100.50
  Bitcoin,BTC,bitcoin,900000000000,48000.00
  Solana,SOL,solana,30000000000,95.25
next: abc123

TOON is also available programmatically:

import { formatToon } from "@opensea/cli"

const data = await client.tokens.trending({ limit: 5 })
console.log(formatToon(data))

CLI Exit Codes

• 0 - Success
• 1 - API error
• 2 - Authentication error

---

Shell Scripts Reference

The scripts/ directory contains shell scripts that wrap the OpenSea REST API directly using curl. These are an alternative to the CLI above.

NFT & Collection Scripts

Marketplace Scripts

Token Swap Scripts

Monitoring Scripts

Supported chains

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

References

• OpenSea CLI GitHub - Full CLI and SDK documentation
• CLI Reference - Complete command reference
• SDK Reference - Programmatic SDK API
• CLI Examples - Real-world usage examples
• 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 CLI, SDK, and REST API scripts)
• OPENSEA_MCP_TOKEN environment variable (for MCP server, separate from API key)
• Node.js >= 18.0.0 (for @opensea/cli)
• curl for REST shell scripts
• websocat (optional) for Stream API
• jq (recommended) for parsing JSON responses from shell scripts

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