langchain-skim

Give your LangChain agent the ability to read any URL — clean Markdown, no ads, no nav, no boilerplate. Two ways to pay: card plan (API key) or x402 wallet pay-per-call.

langchain-skim is the official LangChain tool for Skim — the clean reader API for AI agents. It exposes one tool, SkimReader, that your agent can call to fetch any web page as agent-ready Markdown plus structured metadata (title, byline, published date, language, excerpt). Two ways to pay: card plan with API key (free tier: 1,000 reads/month — skim402.com/pricing) or x402 wallet pay-per-call ($0.002 USDC on Base, no account needed).

See it before you wire it: try Skim free in your browser — 10 free skims a day, no wallet, no signup. Paste a URL, see exactly what your agent gets back.

Install

pip install langchain-skim

This pulls in the x402 client with EVM support, so there's nothing else to install.

Quickstart (60 seconds)

1. Fund a Base wallet with $1 of USDC

A dollar funds roughly 500 reads. Full step-by-step (with screenshots, for non-crypto-native devs): https://skim402.com/wallet.

Use a fresh wallet, not your personal one. This wallet's private key signs payment authorizations on your machine — treat it like a hot wallet for paying $0.002 tolls, not a savings account.

2. Point the tool at your wallet

export SKIM_WALLET_PRIVATE_KEY=0xYOUR_BASE_WALLET_PRIVATE_KEY

3. Use it

from langchain_skim import SkimReader

reader = SkimReader()  # reads SKIM_WALLET_PRIVATE_KEY from the environment

markdown = reader.invoke({"url": "https://en.wikipedia.org/wiki/HTTP_402"})
print(markdown)

The tool signs an EIP-3009 USDC authorization for $0.002, Skim returns clean Markdown, and you get back the article body with a YAML frontmatter block of metadata. The payment shows up in your wallet's transaction history on BaseScan.

Use it in an agent

SkimReader is a standard LangChain BaseTool, so it drops straight into any agent's tool list:

from langchain_skim import SkimReader
from langchain.agents import create_react_agent  # or any agent constructor
from langchain_openai import ChatOpenAI

llm = ChatOpenAI(model="gpt-4o-mini")
tools = [SkimReader()]

agent = create_react_agent(llm, tools)
agent.invoke({"messages": [("user", "Read https://example.com/article and summarize it.")]})

The agent decides when to call skim_read, the wallet pays per read, and the model gets clean Markdown instead of raw HTML.

Output shape

SkimReader returns Markdown with a YAML frontmatter block of the page metadata:

---
title: Example article
byline: Jane Doe
publishedAt: 2025-01-15
lang: en
excerpt: A short summary...
---

# Example article

The cleaned article body in Markdown...

Set include_metadata=False to get just the Markdown body.

Configuration

SkimReader takes the following parameters (all optional except the wallet key):

reader = SkimReader(
    private_key="0x...",       # or rely on the env var
    max_price_usd=0.005,
    include_metadata=False,
)

How it actually works

your agent ──► SkimReader ──► POST https://skim402.com/api/v1/read
                  ▲                       │
                  │                       ▼
                  │              402 Payment Required
                  │                  (x402 challenge)
                  │                       │
                  ▼                       │
   x402 signs EIP-3009 USDC ◄─────────────┘
   transfer authorization (locally)
                  │
                  ▼
        retry POST with X-PAYMENT header
                  │
                  ▼
   Skim verifies + settles via Coinbase CDP facilitator
                  │
                  ▼
        200 OK + clean Markdown

Your private key never leaves your machine — it only signs authorizations locally.

Security

• Dedicated wallet, always. Fund it with only as much USDC as you're willing to spend in a runaway loop. The max_price_usd cap catches accidental price escalations.
• No outbound telemetry from this package. langchain-skim only talks to skim402.com (or whatever you set as base_url). No analytics, no error reporting, no phone-home.

Try it without an agent

Skeptical? Test the upstream endpoint directly — it'll return a 402 challenge so you can see the protocol in action:

curl -i -X POST https://skim402.com/api/v1/read \
  -H 'content-type: application/json' \
  -d '{"url":"https://en.wikipedia.org/wiki/HTTP_402"}'

You'll get back HTTP/1.1 402 Payment Required with the x402 challenge in the response body.

Links

• Skim website — https://skim402.com
• Wallet setup guide — https://skim402.com/wallet
• API docs — https://skim402.com/docs
• x402 protocol — https://x402.org
• GitHub — https://github.com/JessieJanie/skim402

License

MIT