webcli
Click on "Install Server".
Wait a few minutes for the server to deploy. Once ready, it will show a "Started" state.
In the chat, type
@followed by the MCP server name and your instructions, e.g., "@webcliget live crypto prices for bitcoin and ethereum"
That's it! The server will respond to your query, and you can continue using it as needed.
Here is a step-by-step guide with screenshots.
What is webcli?
webcli extracts structured data from websites using an API-first approach -- it tries public APIs, RSS feeds, and structured HTML before ever touching a browser. Built for AI agents that need to read the web.
How it compares to opencli:
opencli | webcli | |
Browser | Reuses your Chrome session | No browser needed for most sites |
Anti-detection | Patches navigator.webdriver, fakes fingerprints | Honest automation, no evasion |
Extension | God-mode Chrome extension (debugger + cookies + all URLs) | No extension at all |
Security | Arbitrary JS in your browser context | Sandboxed V8 isolates, domain-locked fetch |
Agent interface | CLI only | CLI + MCP server |
Auth | Steals your cookies | You provide API keys explicitly |
Related MCP server: @hauntapi/mcp-server
Quick Start
# Clone and install
git clone https://github.com/ashark-ai-05/webcli.git
cd webcli
npm install
# List available adapters
npx tsx src/main.ts list
# Search Hacker News
npx tsx src/main.ts run hackernews search -a query=AI -a limit=5
# Get live crypto prices
npx tsx src/main.ts run coingecko prices -a coins=bitcoin,ethereum,solana
# Search Bluesky users
npx tsx src/main.ts run bluesky search -a query=typescript -a limit=5Built-in Adapters
Hacker News
# Search stories
webcli run hackernews search -a query=rust -a limit=10
# Output as JSON (for piping to other tools)
webcli run hackernews search -a query=rust -f json
# Output as CSV (for spreadsheets)
webcli run hackernews search -a query=rust -f csvCoinGecko
# Live prices
webcli run coingecko prices -a coins=bitcoin,ethereum,solana
# Trending coins
webcli run coingecko trending -a limit=10Bluesky
# Search users
webcli run bluesky search -a query=developer -a limit=5
# Get a profile
webcli run bluesky profile -a handle=bsky.appMCP Server
webcli runs as an MCP server so AI agents (Claude, Cursor, etc.) can use it as a tool.
# Start MCP server
npx tsx src/main.ts --mcpAdd to your Claude Code MCP config:
{
"mcpServers": {
"webcli": {
"command": "npx",
"args": ["tsx", "/path/to/webcli/src/main.ts", "--mcp"]
}
}
}Available MCP tools:
Tool | Description |
| Run any adapter -- extract data from a website |
| List all available adapters |
| Get the data schema of an adapter (field names, types, roles) |
An agent can discover what data a site provides (webcli_schema), then extract it (webcli_run) -- all without any hardcoded knowledge of the site.
YAML Adapter DSL
Every data source is defined as a declarative YAML adapter. Here's the CoinGecko prices adapter:
site: coingecko
name: prices
description: Live cryptocurrency prices
version: 1
source:
type: api
base_url: https://api.coingecko.com/api/v3
auth: none
rate_limit: { requests: 30, per: 60 }
args:
coins: { type: string, default: "bitcoin,ethereum" }
currency: { type: string, default: usd }
schema:
type: price_feed
entity: cryptocurrency
fields:
id: { role: id }
price: { role: value, unit: currency }
change_24h: { role: delta }
market_cap: { role: metric }
update_frequency: "~60s"
pipeline:
- fetch:
url: /simple/price
params:
ids: "${{ args.coins }}"
vs_currencies: "${{ args.currency }}"
include_market_cap: true
include_24hr_change: true
- transform: |
Object.entries(data).map(([id, v]) => ({
id, price: v[args.currency],
change_24h: v[args.currency + '_24h_change'].toFixed(2) + '%',
market_cap: v[args.currency + '_market_cap']
}))
columns: [id, price, change_24h, market_cap]Pipeline Steps
Step | Purpose | Example |
| HTTP request |
|
| Extract nested key |
|
| JS in sandboxed V8 |
|
| Reshape each item |
|
| Keep matching items |
|
| Order results |
|
| Cap result count |
|
| Remove duplicates |
|
| Flatten nested arrays |
|
Architecture
┌─────────┐ ┌────────────┐
│ CLI │ │ MCP Server │
└────┬────┘ └─────┬──────┘
└───────┬──────┘
v
┌────────────────────────┐
│ Core Engine │
│ Pipeline Executor │
│ Adapter Registry │
│ Rate Limiter │
└───────────┬────────────┘
v
┌─────────────────────────────────┐
│ Extractor Cascade │
│ HTTP/API > RSS > HTML > Browser│
└─────────────────────────────────┘
v
┌─────────────────────────────────┐
│ Discovery Engine │
│ Schema Inference │
│ Known Site Registry (8 sites) │
│ Field Role Detection │
└─────────────────────────────────┘
v
┌─────────────────────────────────┐
│ Data Layer │
│ Snapshot Store + Diff Engine │
│ Subscription Manager │
│ Adaptive Interval Scheduler │
└─────────────────────────────────┘Extractor Cascade
webcli tries the lightest extraction method first:
HTTP/API -- Direct JSON API calls. No browser. Fastest.
RSS/Atom -- Feed parsing. Perfect for news sites.
HTML -- JSON-LD, structured data, DOM pattern detection.
Browser -- Playwright (sandboxed). Last resort for SPAs.
90% of useful data is accessible without a browser.
Discovery Engine
Point webcli at any URL and it figures out the data model:
Known Site Registry -- 8 major sites with pre-mapped APIs (CoinGecko, HN, Bluesky, Reddit, StackOverflow, GitHub, X, Wikipedia)
Schema Inference -- Detects field roles (id, title, url, timestamp, score, price, author) from field names and values
Entity Typing -- Classifies data as articles, posts, prices, users, etc.
Security
webcli was designed as a secure alternative to tools like opencli. Every layer has explicit security boundaries:
Sandboxed Expressions
The ${{ }} template engine and transform step run in isolated V8 contexts via vm.createContext:
Available: args, item, index, data, Math, Date, JSON, String, Array, Object
BLOCKED: fetch, require, import, process, globalThis, eval, Function,
setTimeout, Buffer, fs, child_processMemory limit: 64MB. Time limit: 5s for transforms, 1s for expressions.
Domain-Locked Fetch
The fetch pipeline step only makes requests to URLs matching the adapter's declared source.base_url. A CoinGecko adapter cannot make requests to Twitter's API.
Adapter Validation
Every adapter is validated before execution:
Max 20 pipeline steps
Only known step types allowed
Source type and auth method must be from allowed lists
No shell commands anywhere in the pipeline
Rate Limiting
Global and per-site token-bucket rate limiting prevents accidental DoS:
rate_limits:
global: { max_requests_per_minute: 120 }
per_site:
default: { max_requests_per_minute: 30 }
overrides:
api.coingecko.com: 50Honest Automation
No anti-detection. No fingerprint faking. No navigator.webdriver patching. webcli identifies itself honestly:
User-Agent: webcli/0.1.0 (+https://github.com/webcli)If a site blocks us, we escalate gracefully (try browser, then auth, then report blocked) -- we don't start an evasion arms race.
Output Formats
# Pretty table (default)
webcli run hackernews search -a query=AI
# JSON (for piping to jq, agents, scripts)
webcli run hackernews search -a query=AI -f json
# CSV (for spreadsheets, pandas)
webcli run hackernews search -a query=AI -f csvData Layer
Snapshots & Diffs
webcli can track changes over time:
// Snapshot store saves results to ~/.webcli/data/{site}/{name}/
// Diff engine compares snapshots to detect added/removed/changed items
{
"added": [{ "id": "solana", "price": 142.50 }],
"removed": [],
"changed": [{
"id": "bitcoin",
"fields": { "price": { "old": 71000, "new": 71250 } }
}],
"unchanged_count": 1
}Adaptive Polling
Subscriptions automatically adjust their polling frequency:
High volatility (>50% data changed) -- halve the interval
Moderate activity (10-50% changed) -- keep current interval
No changes -- increase interval by 50%
Respects min_interval and max_interval bounds, plus update_frequency hints from the adapter schema.
Development
# Run tests
npm test
# Watch mode
npm run test:watch
# Type check
npm run lint
# Run the CLI in dev mode
npm run dev -- listProject Structure
webcli/
src/
core/ # Pipeline engine, types, adapter system
extractors/ # HTTP, RSS, HTML, cascade
discovery/ # Schema inference, known sites
data/ # Snapshots, diffs, subscriptions
scheduler/ # Adaptive intervals
interfaces/ # CLI (commander) + MCP server
utils/ # Config, logging
adapters/ # Built-in YAML adapters
tests/e2e/ # End-to-end tests (hit live APIs)Writing Custom Adapters
Create a YAML file in ~/.webcli/adapters/{site}/{name}.yaml:
site: mysite
name: feed
description: My custom feed
version: 1
created_by: manual
source:
type: api
base_url: https://api.mysite.com
auth: none
args:
limit: { type: number, default: 10 }
schema:
type: feed
entity: article
fields:
title: { role: title }
url: { role: url }
pipeline:
- fetch: { url: /posts, params: { limit: "${{ args.limit }}" } }
- select: data
- map:
title: "${{ item.title }}"
url: "${{ item.url }}"
date: "${{ item.published_at }}"
- limit: "${{ args.limit }}"
columns: [title, url, date]Validate it:
webcli validate ~/.webcli/adapters/mysite/feed.yamlThen use it:
webcli run mysite feed -a limit=5License
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