skim-haystack

Give your Haystack pipelines 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.

skim-haystack is the official Haystack integration for Skim — the clean reader API for AI agents. It provides one component, SkimReader, that fetches any web page and returns it as a Haystack Document (clean Markdown in content, structured metadata in meta). 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.

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Install

pip install skim-haystack

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

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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 component at your wallet

export SKIM_WALLET_PRIVATE_KEY=0xYOUR_BASE_WALLET_PRIVATE_KEY

3. Use it

from skim_haystack import SkimReader

reader = SkimReader()  # reads SKIM_WALLET_PRIVATE_KEY from the environment

result = reader.run(urls="https://en.wikipedia.org/wiki/HTTP_402")
print(result["documents"][0].content)

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

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Use it in a pipeline

SkimReader is a standard Haystack component, so it drops straight into a Pipeline. Here it fetches a page and feeds the cleaned Markdown into a prompt:

from haystack import Pipeline
from haystack.components.builders import PromptBuilder
from haystack.components.generators import OpenAIGenerator
from skim_haystack import SkimReader

pipe = Pipeline()
pipe.add_component("reader", SkimReader())
pipe.add_component("prompt", PromptBuilder(
    template="Summarize this article in 5 bullets:\n\n{{ documents[0].content }}"
))
pipe.add_component("llm", OpenAIGenerator(model="gpt-4o-mini"))

pipe.connect("reader.documents", "prompt.documents")
pipe.connect("prompt.prompt", "llm.prompt")

result = pipe.run({"reader": {"urls": "https://en.wikipedia.org/wiki/HTTP_402"}})
print(result["llm"]["replies"][0])

The wallet pays per read, and your pipeline gets clean Markdown instead of raw HTML.

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Output shape

SkimReader.run(...) returns {"documents": [Document, ...]} — one Document per URL:

• Document.content — the cleaned article body in Markdown.
• Document.meta — always includes source (the URL), plus page metadata (title, byline, publishedAt, lang, excerpt, ...) unless include_metadata=False.

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Configuration

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

Parameter	Default	Notes
private_key	Secret.from_env_var("SKIM_WALLET_PRIVATE_KEY")	A Haystack Secret with the Base wallet's hex private key. With or without 0x. Pass Secret.from_token("0x...") for an explicit key. Use a dedicated wallet — never your personal one.
base_url	https://skim402.com	Override the API base URL. For self-hosting or local development.
max_price_usd	0.01	Hard cap on per-call price in USD. The wallet refuses to sign for anything above this. Skim is $0.002/call.
include_metadata	True	Populate each Document's meta with page metadata.
timeout	60	Per-request timeout in seconds.

from haystack.utils import Secret
from skim_haystack import SkimReader

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

The component supports pipeline serialization (to_dict/from_dict). When the key comes from an environment variable (the default, or any Secret.from_env_var(...)), it is stored as a reference to that variable name — never the raw value. An inline Secret.from_token("0x...") is intentionally runtime-only: Haystack refuses to serialize token-backed secrets, so it will never be written to disk.

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How it actually works

your pipeline ──► 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.

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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. skim-haystack only talks to skim402.com (or whatever you set as base_url). No analytics, no error reporting, no phone-home.

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Try it without a pipeline

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.

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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

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License

MIT