OpenSea (NFT Marketplace Data + Seaport Trades)

OpenSea is the dominant NFT marketplace. This skill queries marketplace data — listings, offers, sales / events, floor prices, drops, traits — and executes Seaport trades via the official @opensea/cli. For NFT metadata (name, image, traits, ownership) outside the marketplace context, use Alchemy's NFT API instead. For pure cross-chain token swaps (no marketplace context), use the lifi ecosystem skill.

When to use this skill

Use opensea when any of the following are true:

• The user wants marketplace data — listings, offers, floor prices, sales history, collection stats
• The user wants to buy / sell an NFT via Seaport (fulfill listing or accept offer)
• The user wants to search across OpenSea (collections / NFTs / tokens / accounts)
• The user wants to monitor events — sales, transfers, mints, listings, offers — for a collection or NFT
• The user wants to explore drops or build a mint transaction for a SeaDrop contract
• The user wants token discovery in the OpenSea-curated context (top, trending, by group)

When NOT to use this skill (handoff)

Scope contract

This skill covers (scope_in):

• Marketplace data: opensea listings best, opensea listings best-for-nft, opensea offers best-for-nft, opensea offers all, opensea collections stats, opensea collections trending, opensea collections top, opensea collections traits
• Seaport trades: fulfillment data for buying (opensea-fulfill-listing.sh) and selling (opensea-fulfill-offer.sh); creating listings / offers via opensea-post.sh with the Seaport order structure
• Events / monitoring: opensea events list, events by-collection, events by-nft, events by-account — sale / transfer / mint / listing / offer / trait_offer / collection_offer
• Drops + minting: opensea drops list, opensea drops get, opensea drops mint
• Search: opensea search across collections / NFTs / tokens / accounts
• Account utilities: opensea accounts resolve (ENS / username / address)

This skill does NOT cover (scope_out):

• General NFT metadata reads (name, image, traits, ownership, contract metadata) outside the marketplace context → handoff: alchemy-api (NFT API). OpenSea's NFT data is marketplace-flavored and rate-limited; Alchemy's NFT API is broader and cheaper for pure metadata.
• Pure cross-chain token swaps (no NFT marketplace use case) → handoff: lifi (ecosystem skill). OpenSea's swap aggregator works, but lifi covers more bridges and chains.
• Token spot prices for valuation / display → handoff: alchemy-api (Prices API)
• General token metadata, search, list → handoff: alchemy-api (Token API)
• Wallet balances (token + native) → handoff: alchemy-api (Portfolio / Token API)
• Transaction transfer history → handoff: alchemy-api (Transfers API)
• Live RPC reads → handoff: alchemy-cli or alchemy-api (JSON-RPC)
• Pre-execution simulation → handoff: alchemy-api (Simulation API)
• Account abstraction → handoff: alchemy-api (Wallets / Bundler / Gas Manager)
• Embedded / smart wallet onboarding → handoff: alchemy-api (Account Kit)
• Signed tx submission → user wallet (or Privy if configured for OpenSea write flows)

Setup

API key is required. Get one instantly via the auth endpoint (no signup) or register at the developer portal for higher limits:

# Instant key (no signup needed)
export OPENSEA_API_KEY=$(curl -s -X POST https://api.opensea.io/api/v2/auth/keys | jq -r '.api_key')

# Or set an existing key
# export OPENSEA_API_KEY="..."

Install the CLI globally (optional — npx @opensea/cli works without install):

npm install -g @opensea/cli

For write / fulfillment flows that sign with Privy:

export PRIVY_APP_ID="..."
export PRIVY_APP_SECRET="..."
export PRIVY_WALLET_ID="..."

Security: never expose OPENSEA_API_KEY or Privy credentials in client-side code. Server-side only.

Endpoint reference → references/marketplace.md

Marketplace queries (most-used)

Seaport trade execution

Events / monitoring

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

For real-time event streaming: opensea-stream-collection.sh <slug> (requires websocat).

Drops + minting

Search

Quick examples

Get the floor + 24h volume for Bored Apes

opensea collections stats boredapeyachtclub

Find the cheapest listing for a collection

opensea listings best boredapeyachtclub --limit 1

Buy an NFT (fulfill a listing)

# 1. Get the best listing for a specific NFT
opensea listings best-for-nft boredapeyachtclub 1234

# 2. Get fulfillment data — order_hash from above response
./scripts/opensea-fulfill-listing.sh ethereum 0xORDER_HASH 0xYOUR_WALLET

# 3. Sign + submit the returned tx data via your wallet

Stream sales for a collection in real time

./scripts/opensea-stream-collection.sh boredapeyachtclub
# Filters to sale events; pipe through jq to format

Search across types

opensea search "cool cats" --types collection,nft --chains ethereum,base

Common gotchas

• API key is mandatory — even the "instant" tier requires one. The bare REST API will 401 without X-API-KEY.
• OpenSea's NFT data overlaps with Alchemy's NFT API for metadata reads. Prefer Alchemy for general NFT metadata (name, image, traits, ownership across many wallets) — OpenSea is rate-limited harder and adds marketplace flavoring you may not want. Use OpenSea when the marketplace context (listings, offers, sales history, drops) is the actual need.
• Token swap aggregator exists in the OpenSea API (opensea swaps quote), but for pure swap flows without marketplace context, lifi aggregates more bridges + DEXs and is the better default. Use OpenSea swaps when the user is already in an NFT-buying flow that involves a token swap.
• Privy is optional but required for end-to-end write flows. The skill returns fulfillment calldata; how it gets signed is up to the app (user wallet, Privy, or any other signer).
• Order hashes from listings best-for-nft / offers best-for-nft are needed for fulfillment. Don't lose them between API calls.
• Event streaming requires websocat; if not installed, fall back to polling events by-collection with the same filters.
• Slug vs. address: collections are addressed by slug (e.g., boredapeyachtclub), NFTs by (chain, contract, tokenId). Don't mix.

Routing back to Alchemy

If during a session the user's need shifts to surfaces this skill doesn't cover:

• NFT metadata reads (name, image, traits, ownership) — alchemy-api (NFT API) is the right path. OpenSea's NFT API is marketplace-flavored and rate-limited; Alchemy's is broader and faster.
• Token prices, balances, transfer history, general token metadata — alchemy-api
• Live RPC, gas, simulation, AA, Account Kit — alchemy-cli (live) or alchemy-api (app code) or agentic-gateway (no API key)
• Pure cross-chain token swaps — lifi (ecosystem skill); covers 27 bridges + 31 DEXs across 60+ chains

Maintenance: OpenSea maintains @opensea/cli and the underlying API; this skill itself is maintained jointly by Alchemy and OpenSea. File issues against alchemyplatform/skills with [ecosystem/opensea] in the title.