DAPDEV

Posted on Feb 28

How to Spy on Your Competitors' Tech Stack (Ethically)

#startup #webdev #api #productivity

Ever wondered what framework your competitor is using? Or what analytics tool that fast-growing startup runs?

Every website leaks signals about its technology stack — through HTTP headers, JavaScript globals, meta tags, DNS records, and more.

Here's how to detect it programmatically.

The Manual Way (Tedious)

You could open DevTools and look for clues:

X-Powered-By: Express in response headers
<meta name="generator" content="WordPress"> in HTML
window.__NEXT_DATA__ in the console

But this is slow and incomplete. You'd miss DNS-level signals (like Cloudflare), TLS certificate details, or deeply embedded analytics scripts.

The API Way (Fast)

I built TechDetect API — a single endpoint that scans all these layers automatically.

curl "https://techdetect.dapdev.tech/detect?url=https://vercel.com"

Real response:

{
  "url": "https://vercel.com",
  "technologies": [
    {"name": "Next.js", "categories": ["JavaScript Framework"], "confidence": 0.7, "detected_by": ["headers", "html"]},
    {"name": "Vercel", "categories": ["CDN", "Hosting", "PaaS"], "confidence": 0.3, "detected_by": ["headers"]},
    {"name": "SendGrid", "categories": ["Email"], "confidence": 0.2, "detected_by": ["dns"]},
    {"name": "Let's Encrypt", "categories": ["SSL"], "confidence": 0.1, "detected_by": ["tls"]}
  ],
  "meta": {
    "scan_time_ms": 391,
    "layers_used": ["http", "html", "dns", "tls"]
  }
}

In under 400ms, we know Vercel uses Next.js (detected in both headers and HTML), hosts on their own CDN, uses SendGrid for email (found via DNS), and uses Let's Encrypt for TLS.

What Can You Learn?

1. Framework Choices

Is your competitor on Next.js, Nuxt, or a custom SPA? This tells you about their engineering priorities.

2. Infrastructure

Cloudflare vs AWS CloudFront vs Vercel — each choice reveals cost and performance tradeoffs.

3. Email & Communication

SendGrid, Mailgun, Amazon SES — their email provider shows up in DNS records.

4. SSL Provider

Let's Encrypt vs DigiCert vs Cloudflare — detected from TLS certificate inspection.

Practical Example: Competitive Analysis Script

import httpx

API_URL = "https://techdetect.dapdev.tech/detect"
competitors = [
    "https://stripe.com",
    "https://vercel.com",
    "https://linear.app",
    "https://notion.so",
]

for url in competitors:
    resp = httpx.get(API_URL, params={"url": url})
    data = resp.json()
    techs = data.get("technologies", [])
    scan_ms = data.get("meta", {}).get("scan_time_ms")

    print(f"\n{url} ({scan_ms}ms)")
    for tech in techs:
        cats = ", ".join(tech["categories"])
        sources = ", ".join(tech["detected_by"])
        print(f"  {tech['name']} [{cats}] (via {sources})")

Output:

https://stripe.com (1477ms)
  Next.js [JavaScript Framework] (via html)
  Nginx [Web Server] (via headers)
  DigiCert [SSL] (via tls)

https://vercel.com (391ms)
  Next.js [JavaScript Framework] (via headers, html)
  Vercel [CDN, Hosting, PaaS] (via headers)
  SendGrid [Email] (via dns)
  Let's Encrypt [SSL] (via tls)

How Detection Works

TechDetect scans 4 layers simultaneously:

Layer	What it checks	Example findings
HTTP	Response headers, server headers	Nginx, Express, Cloudflare
HTML	Meta tags, script patterns, DOM	Next.js, React, WordPress
DNS	MX, TXT, CNAME records	SendGrid, Google Workspace
TLS	Certificate issuer, SAN entries	Let's Encrypt, DigiCert, AWS

141+ technologies across 15 categories — all in a single API call.

Try It

The API is available on RapidAPI with a free tier:

TechDetect API on RapidAPI →

Also available as:

PyPI package — pip install techdetect
npm package — npm install techdetect
Apify Actor

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