AlterLab API Documentation
AlterLab is a web scraping API that handles anti-bot protections, CAPTCHAs, and JavaScript challenges in a single API call. It returns clean HTML, LLM-ready markdown, or structured JSON from any URL.
The API uses a 5-tier auto-escalation system: Tier 1 (Light, $0.0002/req) for static sites, Tier 2 (Standard, $0.0003/req) for TLS-fingerprinted requests, Tier 3 (Protected, $0.002/req) for anti-bot protection, Tier 4 (Dynamic, $0.004/req) for JavaScript rendering, and Tier 5 (Fortress, $0.02/req) for challenge resolution. Official SDKs are available for Python and Node.js. Pay-as-you-go pricing with no monthly subscription — balance never expires.
What does the AlterLab API do?
AlterLab is a web scraping API that converts any public URL into structured data with a single HTTP request. Submit a URL and receive clean markdown, plain text, or typed JSON — depending on the output format requested. AlterLab handles JavaScript rendering (via headless Chromium), website compatibility (via TLS fingerprinting and behavioral signals), and challenge resolution automatically. Pricing starts at $0.0002 per request for static pages and scales to $0.02 per request for challenge-protected targets. There is no monthly subscription and account balance never expires. Official SDKs are available for Python (pip install alterlab) and Node.js (npm install @alterlab/sdk), with an MCP Server for direct integration with Claude, Cursor, and Windsurf.
New to AlterLab?
How do I get started with AlterLab?
Install the SDK with pip install alterlab (Python) or npm install @alterlab/sdk (Node.js). Sign up at alterlab.io to get 5,000 free requests — no credit card required. Send a URL to the /scrape endpoint with your API key and receive clean HTML, markdown, or JSON in one call.
What can AlterLab extract from a website?
AlterLab returns raw HTML, LLM-ready markdown, or structured JSON from any public URL. For structured extraction, define a JSON schema (fields, types) and AlterLab uses AI to populate it automatically. Supports product prices, job listings, real estate data, and any page with structured content.
How do I get started with AlterLab?
Installation
Install the SDK in your preferred language and set up your environment.
Your First Request
Make your first API call and scrape a web page in under 2 minutes.
REST API Reference
Complete reference for all API endpoints, parameters, and responses.
Python SDK
Official Python SDK with async support, batch operations, and type hints.
Guides
JavaScript Rendering
Scrape SPAs and dynamic sites with headless browser rendering.
PDF & OCR
Extract text from PDFs and images with multi-language OCR support.
Caching
Reduce costs with intelligent caching. Cache hits are free.
Webhooks
Get notified when async scrapes complete with webhook callbacks.
JSON Schema Filtering
Filter extracted data to match your desired output structure with aliases and type coercion.
Batch Scraping
Submit up to 100 URLs in a single API call with async processing and webhooks.
Scheduler
Automate recurring scrapes with cron expressions and balance-based limits.
Authenticated Scraping
Scrape login-gated content with your own session cookies. Member pricing, paywalled articles, and more.
Tutorials
Reference
Pricing
Tier costs, add-ons, BYOP discounts, and concurrency limits.
Rate Limits
Quotas, payload limits, timeouts, and how to handle 429 errors.
Error Codes
Complete list of error codes with troubleshooting tips.
API Keys
Manage API keys, permissions, and security best practices.
Quick Links
Interactive Playground
Test API requests in real-time with our interactive tool
Bring Your Own Proxy
Use your own proxies for up to 20% cost savings
Migrate from Firecrawl
Switch from Firecrawl with our compatibility layer
Compare with Alternatives
See how AlterLab compares to ScraperAPI, Firecrawl, and others
See Also
Blog & Tutorials
Web scraping guides, website compatibility techniques, and code examples
Pricing
5-tier pricing from $0.0002/request. Pay-as-you-go, credits never expire
Compare Scraping APIs
AlterLab vs ScraperAPI, Firecrawl, ScrapingBee, and Bright Data
Automatic Website Compatibility
Handles bot-protected websites, CAPTCHAs, and JavaScript challenges automatically
Explore the Web Scraping API Cluster
Side-by-side comparison with ScraperAPI, Firecrawl, Bright Data, and Apify.
Real success rates, response times, and cost data across all 5 tiers.
Use web scraping in Claude, GPT-4, and LangChain agent workflows.
Handles bot-protected websites, JavaScript challenges, and complex protections automatically.
Full browser rendering for SPAs, React, and dynamic content.
Chain Search → Crawl → Map operations in a single API workflow.
From $0.0002/request. Balance never expires — no monthly subscription.