Node-Unblocker for Web Scraping: What It Is and How It Works

When scraping websites with Node.js, defensive mechanisms such as rate limits, IP blocks, geo-restrictions, and basic bot detection can quickly break a simple HTTP request.

One tool developers sometimes use to work around these limits—especially in lightweight or experimental scraping workflows—is Node-Unblocker. It is an open-source proxy middleware library for Node.js and Express.

Node-Unblocker allows you to build a local proxy server that reroutes outgoing HTTP requests through your own application. Instead of requesting a target website directly, your scraper fetches content through this proxy, which can help bypass basic host-level restrictions.

In this article, we’ll explore what Node-Unblocker is, how it works, how to set it up for scraping, and how it compares to managed proxy solutions like Mrscraper for larger-scale scraping.

What Node-Unblocker Is and How It Works

Node-Unblocker is an npm package originally designed as a web proxy for bypassing blocks and censorship. In a scraping context, it acts as a relay:

1. Your scraper sends a request to the proxy
2. Node-Unblocker forwards the request to the target site
3. The response is streamed back through the proxy to your scraper

Internally, Node-Unblocker handles tasks such as:

• Rewriting relative URLs
• Adjusting cookie paths
• Maintaining basic session continuity

It is typically attached to an Express server as middleware so that requests made to a specific route prefix (for example, /proxy/) are automatically forwarded to external sites.

Setting Up Node-Unblocker in Express

Below is a minimal example of setting up a Node-Unblocker proxy server.

Initialize a New Project

mkdir node-unblocker-proxy
cd node-unblocker-proxy
npm init -y

Install Dependencies

npm install express unblocker

Create proxy-server.js

const express = require("express");
const Unblocker = require("unblocker");

const app = express();

// Unblocker will handle all routes under /proxy/
const unblocker = new Unblocker({ prefix: "/proxy/" });
app.use(unblocker);

// Start the proxy server
const PORT = process.env.PORT || 3000;
app.listen(PORT, () => {
  console.log(`Proxy server running at http://localhost:${PORT}/proxy/`);
}).on("upgrade", unblocker.onUpgrade);

Start the Server

node proxy-server.js

You can now access proxied pages in a browser:

http://localhost:3000/proxy/https://example.com

Node-Unblocker will forward the request and return the proxied response.

Using the Proxy in a Web Scraper

Node-Unblocker itself does not scrape or parse data—it only forwards requests. To extract data, you still need a scraper client.

Here’s a simple example using axios.

Example Scraper (scraper.js)

const axios = require("axios");

// Base URL of your proxy server
const PROXY_BASE = "http://localhost:3000/proxy/";
const TARGET_URL = "https://www.example.com";

(async () => {
  try {
    const response = await axios.get(PROXY_BASE + TARGET_URL, {
      headers: {
        "User-Agent": "Mozilla/5.0 (compatible; Node Scraper)"
      }
    });

    console.log("HTML length:", response.data.length);
    // Parse response.data using Cheerio or another parser
  } catch (err) {
    console.error("Error scraping through proxy:", err.message);
  }
})();

In this setup, your scraper treats the proxy as the origin, while Node-Unblocker handles the outbound request to the target site.

Advanced Request and Response Middleware

Node-Unblocker supports middleware hooks that let you modify requests and responses before they are forwarded or returned.

Modifying Outgoing Requests

function addAuthHeaders(data) {
  if (/^https?:\/\/api\.example\.com/.test(data.url)) {
    data.headers["x-scrape-token"] = "my_token_value";
  }
}

const unblockerConfig = {
  prefix: "/proxy/",
  requestMiddleware: [addAuthHeaders]
};

app.use(new Unblocker(unblockerConfig));

Modifying Incoming Responses

For example, stripping <script> tags from HTML responses:

function stripScripts(data) {
  if (data.contentType.includes("text/html")) {
    data.stream = data.stream.pipe(
      through(function (chunk, enc, next) {
        this.push(
          chunk
            .toString()
            .replace(/<script[^>]*>.*?<\/script>/g, "")
        );
        next();
      })
    );
  }
}

app.use(
  new Unblocker({
    responseMiddleware: [stripScripts]
  })
);

While powerful, these techniques increase complexity and maintenance overhead.

Integrating with Browser Automation (Puppeteer / Playwright)

Node-Unblocker can also be used with headless browsers:

const puppeteer = require("puppeteer");

(async () => {
  const browser = await puppeteer.launch();
  const page = await browser.newPage();

  await page.goto("http://localhost:3000/proxy/https://example.com");
  const html = await page.content();

  console.log("Page HTML preview:", html.substring(0, 500));
  await browser.close();
})();

This approach can help when scraping sites that require JavaScript execution, though advanced bot protection systems may still block traffic.

Limitations of Node-Unblocker for Scraping

While useful, Node-Unblocker has notable limitations:

• No proxy rotation or IP pool: A single server IP is easily blocked at scale
• Weak against advanced anti-bot systems: Cloudflare and similar defenses often detect simple proxies
• Not scraping-focused: No structured output, retry logic, or built-in parsing

As a result, Node-Unblocker is best suited for development, testing, or low-volume scraping rather than production-scale data collection.

Mrscraper’s Proxy Feature for Scalable Scraping

For teams running large or long-term scraping workloads, Mrscraper provides managed proxy infrastructure integrated directly into its scraping API:

• Automated proxy rotation without local servers or middleware
• Anti-blocking techniques designed for real-world scraping targets
• Unified scraping and proxy access, returning structured data formats

This approach removes the need to maintain custom proxy servers and simplifies scaling.

Conclusion

Node-Unblocker provides a quick way to spin up a local proxy server in Node.js and route scraping traffic through Express middleware. It integrates well with HTTP clients like axios and browser automation tools like Puppeteer.

For small projects or experimentation, this level of control can be useful. However, as scraping requirements grow—especially when proxy rotation, anti-bot handling, and scalability become critical—managed solutions like Mrscraper help reduce operational overhead and improve reliability.