An interface for reading data from OpenSea, a marketplace for non-fungible tokens (NFTs), which are unique blockchain-based digital items. It uses OpenSea's REST and real-time Stream APIs.

Use it to build NFT dashboards and applications, retrieve listings and offers, inspect collection details, or monitor sales, transfers, and listings in real time.

It removes the need to design direct integrations for NFT metadata, collections, marketplace activity, ownership, and events. An OpenSea API key is required.

opensea-api — Skill for Claude Code by ckorhonen

Install

Getting it into your agent

One page per mod, every tool's command on it. A separate URL per tool would split the same page into five that compete with each other.

Any agent

npx skills add ckorhonen/claude-skills --skill opensea-api

Clone the repo

git clone --depth 1 https://github.com/ckorhonen/claude-skills

Made for: Claude Code.

Or install claude-skills, the plugin that ships this one along with the rest of its 62 skills, 4 commands, 7 agents.

Wrote this? Show the measurements

A badge with what this costs and how it scanned, read live from this page, so it follows the numbers instead of freezing them. Markdown for a README, HTML for a documentation site or a project page.

README.md

[![agentmods](https://agentmods.dev/badge/skills/ckorhonen/claude-skills/opensea-api/github.svg)](https://agentmods.dev/skills/ckorhonen/claude-skills/opensea-api)

Your own site

<a href="https://agentmods.dev/skills/ckorhonen/claude-skills/opensea-api"><img src="https://agentmods.dev/badge/skills/ckorhonen/claude-skills/opensea-api/github.svg" alt="Measured on agentmods" height="20"></a>

Or the 80×15 button, for a site that already has a row of RSS and ATOM ones. Only the verdict fits; the numbers stay here.

Your own site · 80×15

<a href="https://agentmods.dev/skills/ckorhonen/claude-skills/opensea-api"><img src="https://agentmods.dev/badge/skills/ckorhonen/claude-skills/opensea-api.svg" alt="Reviewed on agentmods" width="80" height="20"></a>

Per session 42 Skills are progressive disclosure: only the name and description are preloaded; the body loads when the skill is used.

When invoked 4,805 The whole file, excluding the scripts and references it only reads on demand.

Security scan A 1 finding. A grade says what 26 rules found in the file — not that it is safe.

Origin original No closer match found in the catalogue.

Token cost

What it costs to keep this loaded

Counted locally with the o200k_base tokenizer, which is exact for GPT models; Claude uses its own tokenizer and its counts differ. Treat this as one consistent yardstick across the catalogue rather than a bill. Prices are per million input tokens.

Model	Per session	Once invoked
Fable 5.1	$0.00042	$0.04805
Opus 5	$0.00021	$0.02403
Sonnet 5	$0.00008	$0.00961
Haiku 4.5	$0.00004	$0.00481

Measured 10d ago against content hash 8ddc2685491b, method: parsed. Prices are Anthropic first-party input rates as of 2026-09-10, from the pricing page.

Security

Grade A, and why

opensea-api scanned grade A with 1 finding against 26 rules in 11 categories — prompt injection, anti-refusal, data exfiltration, privilege escalation, supply chain, agent snooping, system-prompt leakage, SSRF and excessive agency — measured 10d ago.

The scan reads SKILL.md. This mod also ships 4 executable files (scripts/collection_stats.sh, scripts/fetch_nft.sh, scripts/monitor_collection.sh, …), listed below but not scanned — reading those needs a real analyzer, not pattern matching.

A static scan of the body, not an audit. Every finding is printed with the line that produced it so you can judge whether it matters here. A mod is markdown that instructs an agent; that is exactly why what it instructs is worth reading.

Makes network callslowCapability

Not a fault in itself. Listed so you know the mod talks to something, and to what.

- `curl` for HTTP requests

skills/opensea-api/SKILL.md · 647 lines

How it starts

The opening of the file, as written. The whole thing — 647 lines — stays where its author put it; the contents beside it link to each section on GitHub.

OpenSea API

Overview

Interact with OpenSea's NFT marketplace through their REST API and real-time Stream API. Fetch NFT metadata, collection information, listings, offers, and events across multiple blockchains including Ethereum, Polygon, Base, Arbitrum, and more.

When to Use

Fetching NFT metadata, traits, and ownership information
Getting collection details and statistics
Retrieving active listings and offers
Tracking NFT events (sales, transfers, listings)
Building NFT dashboards and analytics tools
Real-time monitoring of marketplace activity
Integrating NFT data into applications

Prerequisites

OpenSea API key (free tier available)
curl for HTTP requests
jq for JSON parsing (brew install jq on macOS, apt install jq on Linux)
For Stream API: Node.js with @opensea/stream-js or Python with opensea-stream

Getting an API Key

Visit OpenSea Developer Portal
Create a developer account
Generate an API key
Set the environment variable:

export OPENSEA_API_KEY="your-api-key"

Add to your shell profile (~/.zshrc or ~/.bashrc) for persistence:

echo 'export OPENSEA_API_KEY="your-api-key"' >> ~/.zshrc

API Base URL

https://api.opensea.io

All requests require the API key in the header:

-H "X-API-KEY: $OPENSEA_API_KEY"

Rate Limits

Request Type	Rate Limit
GET requests	4/second per API key
POST requests	2/second per API key

For higher limits, apply at the OpenSea Developer Portal.

Supported Blockchains

Chain	API Name
Ethereum	`ethereum`
Polygon	`matic`
Arbitrum	`arbitrum`
Optimism	`optimism`
Base	`base`
Avalanche	`avalanche`
Blast	`blast`
Zora	`zora`
Solana	`solana`

Quick Start

Fetch an NFT:

curl -X GET "https://api.opensea.io/api/v2/chain/ethereum/contract/0xBC4CA0EdA7647A8aB7C2061c2E118A18a936f13D/nfts/1" \
  -H "X-API-KEY: $OPENSEA_API_KEY"

Read the full file on GitHub · 647 lines

Files

What ships with it

4 files beside SKILL.md in the same directory: the scripts, references and assets a skill reads on demand. Not counted in the per-session cost; read them before you install if any of them is executable.

Changes

What this file has done since we first saw it

Hashed on every crawl. A supply-chain change to an agent config is a question of when, not whether, so the history is kept rather than the latest state alone.

10d ago First seen · 647 lines · 42 tokens per session scan A 8ddc2685491b

Subscribe to this mod's changes

opensea-api is a skill published in the GitHub repository ckorhonen/claude-skills (14 stars, last pushed 2mo ago), licensed MIT. It adds 42 tokens to every session and 4,805 once invoked, about $0.0002 per session on Opus 5. A static security scan graded it A with 1 finding (makes network calls). No closer match exists in the catalogue, so it is treated as the original; first seen 2026-08-30.

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opensea-api