5 Best Tools for Extracting API Data From Websites

Every modern website sits on top of APIs. When you search on Amazon, your browser calls an internal product search endpoint. When you scroll your Twitter feed, the client hits a GraphQL timeline API. When you check flight prices on Google Flights, the frontend is fetching from a structured data service.

These internal APIs -- sometimes called shadow APIs, private APIs, or undocumented APIs -- contain the exact same data the website displays, but in clean, structured JSON format. If you can discover and call them directly, you skip the entire scraping pipeline: no rendering, no parsing, no anti-bot evasion.

Here are the five best tools for extracting API data from websites in 2026.

1. Unbrowse

Best for: Automated API discovery and shared route caching

Unbrowse automates the entire API discovery process. You browse a website normally, and Unbrowse passively captures every API call the frontend makes. It then reverse-engineers the endpoint schemas, extracts authentication patterns, generates documentation, and stores the routes in a shared cache.

The next time any user or agent needs data from that domain, Unbrowse checks the route cache first. If a matching API endpoint exists, it calls the API directly -- returning structured JSON in under a second. No browser, no scraping, no DOM parsing.

How it works:

1. Install Unbrowse: npx unbrowse setup
2. Browse any website through the Unbrowse proxy
3. Unbrowse intercepts all XHR/fetch requests and HAR traffic
4. Endpoints are extracted, deduplicated, and documented
5. Routes are published to a shared marketplace
6. Future requests resolve from cache in ~950ms average

Key differentiators:

• Passive discovery: no manual traffic analysis required
• Shared marketplace: routes indexed by any user benefit all users
• Full enrichment pipeline: endpoints get auto-generated documentation, schema extraction, and semantic metadata via LLM augmentation
• MCP server integration for Claude and other AI clients
• x402 micropayments: users earn by discovering new routes
• Works for REST, GraphQL, and WebSocket endpoints

Best for: Teams that want to scale API discovery across hundreds of domains without manual reverse engineering.

Limitation: Requires at least one browsing session per domain to discover routes. Some complex authentication flows (like OAuth dance sequences) may need manual intervention.

2. mitmproxy

Best for: Deep traffic inspection and manual API reverse engineering

mitmproxy is the industry-standard open-source proxy for intercepting HTTP and HTTPS traffic. It gives you complete visibility into every request between a client (browser, mobile app, or API client) and the server.

How it works:

1. Configure your browser or device to route traffic through the mitmproxy
2. Install the mitmproxy root certificate for HTTPS inspection
3. Browse the target website or use the target application
4. mitmproxy captures and displays every request and response in real time
5. Inspect headers, payloads, cookies, and authentication tokens
6. Use mitmproxy2swagger to auto-generate OpenAPI specifications from captured traffic

Key features:

• Console, web, and dump interfaces for different workflows
• Python scripting for automated request modification and filtering
• SSL/TLS interception with certificate pinning bypass
• WebSocket and HTTP/2 support
• Flow export to cURL, Python, and other formats
• mitmproxy-MCP: an MCP server that lets AI agents inspect and replay traffic

Best for: Security researchers, reverse engineers, and developers who need to understand exactly what API calls an application makes.

Limitation: Entirely manual process. You capture traffic, you analyze it, you document the endpoints, you maintain the documentation. No sharing mechanism between users. Setting up SSL interception on mobile devices requires root/jailbreak access.

3. Charles Proxy

Best for: GUI-based API inspection with powerful filtering

Charles Proxy provides a polished desktop GUI for intercepting and analyzing HTTP/HTTPS traffic. It is the preferred tool for many mobile and web developers who want visual traffic inspection without command-line complexity.

How it works:

1. Launch Charles Proxy and configure your system or browser proxy settings
2. Install the Charles root certificate for SSL inspection
3. Browse the target website normally
4. Charles captures all traffic in an organized tree view (by host/path) or sequence view (by time)
5. Click any request to inspect headers, request body, response body, timing, and cookies
6. Use breakpoints to pause and modify requests in flight

Key features:

• Structure view groups requests by domain and path for easy navigation
• Sequence view shows requests in chronological order
• Breakpoints let you pause, inspect, and modify requests and responses mid-flight
• Repeat and Repeat Advanced for stress testing specific endpoints
• Map Local/Map Remote for response substitution
• Bandwidth throttling for simulating slow connections
• Export sessions for sharing with team members

Best for: Developers and QA engineers who prefer a visual interface for API discovery. Excellent for mobile app API reverse engineering since it works as a system-level proxy.

Limitation: Commercial software ($50 license). Manual analysis only -- no automation or sharing of discovered endpoints. Limited scripting capabilities compared to mitmproxy. Not designed for AI agent integration.

4. Postman Interceptor

Best for: Capturing browser API calls and immediately testing them

Postman Interceptor bridges the gap between browser traffic capture and API testing. It is a browser extension that captures API calls as you browse and sends them directly to Postman, where you can inspect, modify, and replay them.

How it works:

1. Install the Postman Interceptor browser extension (available for Chrome, Firefox, Safari, and Edge)
2. Connect the extension to your Postman desktop app
3. Start a capture session and browse the target website
4. Every API call the browser makes appears in Postman in real time
5. Click any captured request to open it as a Postman request
6. Test, modify parameters, and save to collections for reuse

Key features:

• Automatic cookie sync from browser to Postman cookie jar
• Request filtering by URL pattern, method, or content type
• Save captured requests directly to Postman collections
• Encrypted communication between extension and Postman
• Works across Chrome, Firefox, Safari, and Edge

Best for: Developers who already use Postman and want to quickly capture, test, and document API endpoints from websites they browse.

Limitation: Tied to the Postman ecosystem. Captured requests require manual curation to identify the important endpoints from the noise of tracking pixels, analytics calls, and CDN requests. No automated schema generation. No sharing mechanism.

5. HAR Analyzers

Best for: Post-hoc analysis of browser network traffic

Every modern browser can export its network activity as a HAR (HTTP Archive) file. HAR analyzers parse these files to extract API endpoints, identify patterns, and generate documentation.

How it works:

1. Open your browser's DevTools (F12) and navigate to the Network tab
2. Browse the target website, performing the actions you want to capture
3. Right-click in the Network tab and select "Export HAR"
4. Import the HAR file into an analyzer tool
5. The analyzer categorizes requests, identifies API patterns, and extracts endpoints

Popular HAR analysis tools:

• HAR Viewer (open source): Visual timeline of all requests with filtering
• mitmproxy2swagger: Converts HAR files to OpenAPI 3.0 specifications
• httparchive.org tools: Community analysis and benchmarking
• Custom scripts: Python's haralyzer library for programmatic analysis

Key features:

• No proxy setup required -- use built-in browser DevTools
• Capture complete request/response including timing data
• Works on any website without additional configuration
• Shareable file format for team collaboration
• Can be integrated into CI/CD pipelines for regression detection

Best for: Quick one-off API discovery when you do not want to set up a proxy. Also valuable for documenting API behavior over time by comparing HAR files from different sessions.

Limitation: Post-hoc analysis only -- you cannot modify or replay requests from a HAR file directly. Large HAR files from complex sites can be hundreds of megabytes. No real-time capture or automation.

Comparison Table

Tool	Automation	Real-time	Sharing	AI Integration	Cost
Unbrowse	Fully automated	Yes	Marketplace	MCP server	Free + micropayments
mitmproxy	Scriptable	Yes	Manual export	MCP server (community)	Free
Charles Proxy	Manual	Yes	Session export	None	$50 license
Postman Interceptor	Manual	Yes	Collections	None	Free (Postman req.)
HAR Analyzers	Semi-automated	No (post-hoc)	File sharing	None	Free

The Paradigm Shift

The fundamental difference between these tools comes down to automation and sharing:

Manual tools (mitmproxy, Charles, Postman Interceptor, HAR analyzers) require a human to browse, capture, analyze, and document API endpoints. Every team repeats this work independently for every domain they need to access.

Automated tools (Unbrowse) do this work once and share the results. When one developer discovers Reddit's internal API endpoints, every other Unbrowse user can call those endpoints without repeating the discovery process.

This is the same shift that happened with package managers. Before npm, every JavaScript developer downloaded and managed libraries manually. After npm, discovering a library once meant everyone could npm install it instantly. Unbrowse is doing the same for API routes: discover once, call from anywhere.

For AI agents specifically, the shared route cache is transformative. An agent that needs to "check the weather" does not need to launch a browser, navigate to weather.com, and scrape the results. It calls unbrowse resolve "weather forecast for San Francisco" and gets back structured JSON from a pre-indexed API endpoint in under a second.

The tools on this list serve different stages of API discovery maturity. Start with HAR analyzers and Postman Interceptor for manual exploration. Move to mitmproxy when you need scripting and depth. And when you are ready to scale API discovery across your organization or agent fleet, Unbrowse eliminates the manual work entirely.