Top 7 Bot Blockers in 2025: Challenges for Modern Web Scraping

Watching your painstakingly written script fail repeatedly can be a frustrating ordeal. You spend hours refining your selectors and logic, only to get hit with more 403 Forbidden errors.

The reality is the web isn’t as open as it used to be. Most major websites are now protected by sophisticated bot blockers designed to aggressively filter out anything that doesn’t look or act human. 

While these measures are meant to stop malicious bot traffic and bad bots, the unfortunate side effect is that legitimate crawlers and scrapers often get caught in the crossfire. These bot protection systems aren’t just checking user agents anymore, but they are monitoring non-linear browsing behaviors, fingerprinting your TLS handshake, and banning suspicious IP addresses instantaneously.

When you hit these walls, you generally have two choices: You can spend valuable development time engineering complex workarounds for proxy rotations and headless browsers, or you can offload that headache to a tool built to handle it for you, like ScraperAPI.

In this guide, I discuss the seven toughest bot detection providers and why they’re so hard to bypass. Then, you’ll see how ScraperAPI bypasses them automatically, with ease.

TL;DR: Bot Blockers Difficulty Breakdown

The table below gives a quick overview of each bot blocker, highlighting the detection system used, the difficulty level, and the specific technical hurdles associated with each: 

Evaluating Bot Blockers

When I call a blocker “tough”, I mean more than “it threw a few 403s.” That is why this ranking is based on three things: 

1. How deeply the detection really penetrates 
2. How often you run into it in real traffic 
3. How much effort it takes to build and keep a stable bypass

For points two and three, we’re using our internal metrics to rank bot blockers by how often our customers encounter them, and by the complexity of bypassers our dev team needs to build and maintain to keep scrapers unnoticed.

The 7 Top Bot Blockers Scrapers Need to Know

Not all bot blockers are as impenetrable as they seem. Some are like speed bumps that require you to go around them slowly using proxies, while others are full-blown fortresses that analyze your mouse movements, TLS fingerprints, and employ all sorts of sophisticated mechanisms to block your scrapers. 

Below are 7 providers that give devs the biggest headaches. I’ve ranked them based on the sophistication level of their detection methods and the engineering effort required to get past them.

1. Akamai

Akamai powers the infrastructure for many major banks, airlines, and eCommerce platforms, and sees enough global traffic to spot anomalies with unmatched precision. It doesn’t just check what you are requesting, but also how your device built the connection.

• Standout Features: Akamai utilizes deep “sensor data”, which is an encrypted payload that checks everything from your battery status to canvas rendering. It also uses JA3/JA4 fingerprinting to analyze the specific cryptographic “handshake” your browser makes.
• Performance: It’s extremely aggressive yet accurate. Their low false-positive rate allows admins to block suspicious traffic instantly without fear of rejecting legitimate users.
• Challenge of Bypassing: Standard automation tools (Puppeteer/Selenium) are dead on arrival here. Success requires pristine residential IP addresses and specialized clients that perfectly mimic a real browser’s TLS fingerprint. If your request data feels even slightly synthetic, you’re blocked.

2. DataDome

DataDome focuses on bot mitigation (not a CDN add-on), making it highly reactive to threats. Chances are, if you do find a workaround, its machine learning engine will patch the breach, globally, within a short period.

• Standout Features: DataDome specializes in mapping mismatches between declared specs and your actual hardware. It’s like when you set your scraper’s User-Agent to say: “I am a generic Android phone,” but DataDome queries for the hardware specs and sees a device with 64 CPU cores. No Android phone has 64 cores; consequently, you get blocked.
• Performance: It blocks threats in real-time (milliseconds) and has a dashboard that gives admins real-time overview of “attacks”, encouraging them to be aggressive with blocking rules.
• Challenge of Bypassing: Data Center IP addresses are banned instantly. To pass, you typically need high-quality 4G/5G mobile proxies (which share IPs with real humans) and a browser automation setup that completely hides the “WebDriver” property.

3. PerimeterX (HUMAN)

PerimeterX (now part of HUMAN) cares less about your network settings and more about your “human nature”. It obsesses over user behavior – how you interact with the page before you even click a button.

• Standout Features: The “Human Challenge” involves tracking the trajectory of your mouse, scroll speed, and keystroke micro-timing to build a behavioral fingerprint. And, because it integrates via JavaScript SDKs into websites it protects, it has full visibility into client-side execution, allowing it to flag perfect traffic that lacks the messy, chaotic movement of a real human.
• Performance: PerimeterX is mainly optimized for modern web apps and eCommerce platforms. While most security providers (like Cloudflare) check your ID at the front door, PerimeterX lets traffic flow until a critical action (like “Add to Cart”) occurs, then clamps down if the bot activity looks robotic.
• Challenge of Bypassing: The real challenge is being convincing enough for the system to pass off your requests as “authentically human. Because real human engagements are often messy, your bot can’t simply teleport the mouse to a button; it has to inject calculated noise to mimic the friction of a human hand. Even this may not be enough.

4. CloudFlare

Cloudflare sits in front of millions of sites, from hobby blogs to large enterprises, which gives it very broad visibility into IP and bot behavior across the web. Their protection ranges from free Bot Fight Mode to enterprise-grade Bot Management.

• Standout Features: It relies on the “Turnstile” challenge and rigorous TLS fingerprinting. If an IP address acts suspiciously on one Cloudflare site, it immediately loses reputation across the entire Cloudflare network.
• Performance: Detection occurs at the network edge, making it very fast. CloudFlare frequently uses “waiting rooms” to stall and frustrate bots without explicitly blocking them.
• Challenge of Bypassing: For Enterprise-protected sites, the primary blocker is the TLS handshake. Standard Python libraries get detected immediately. You’d want to use tools (like curl_cffi or specialized browsers) that can spoof the cryptographic handshake of a real web browser, if you want to even attempt breaking through.

5. Fastly

Fastly is a high-performance edge platform. Their security relies on strict adherence to web protocols rather than black box AI behavior tracking.

• Standout Features: It uses VCL (Varnish Configuration Language) to enforce logic at the edge. It’s particularly strict about HTTP request header ordering and formatting. It also supports aggressive rate limiting logic custom-written by the site admin.
• Performance: Very low latency. Because the security logic runs directly on the caching servers, it has minimal impact on site speed or user experience.
• Challenge of Bypassing: Fastly blocks based on technical protocol violations. If your scraper sends headers in the wrong order (for example, sending Accept before Host when a real browser does the opposite), it will block you. Bypassing Fastly is less about mimicking user behavior and more about ensuring your HTTP request is structurally perfect. Still, it doesn’t necessarily make it easier.

6. Amazon WAF

Amazon WAF is more of an infrastructure, rather than a managed service (unless you pay extra). Out of the box, it is a set of tools that you’d have to configure yourself.

• Standout Features: The major plus is that it integrates naturally with AWS services. While they offer a Bot Control managed rule set, it is expensive, so many site owners rely on simple rate-limiting rules instead.
• Performance: Highly scalable, but the detection logic is often static (blocking an IP address after an X number of requests) rather than purely behavioral.
• The Challenge: Generally, I consider it one of the easiest to bypass on this list. Unless the administrator can write super complex rules. Standard IP rotation and respecting rate limits are usually sufficient to bypass it.

7. open-appsec

open-appsec is an open-source web application and API security engine that relies on machine learning rather than static signatures to protect client websites. It does this by building an understanding of how your specific application normally behaves and uses that context to flag abnormal or risky traffic.

• Standout Features: open-appsec combines a supervised ML model (trained offline on millions of benign and malicious requests) with an online, environment-specific model that learns from your live traffic. This dual approach helps it detect both known and emerging attacks with fewer false positives and less manual tuning than a traditional WAF (Web Application Firewall).
• Performance: It is built for cloud-native, containerized environments, with automation that fits CI/CD workflows and infrastructure-as-code. The ML engine evaluates HTTPS requests in real time and is engineered to provide preemptive protection with little configuration overhead.
• Challenge of bypassing: Because enforcement is driven by a contextual ML model rather than a fixed signature set, there isn’t a simple list of rules for you to study and evade. The engine weighs multiple signals (request content, behavior patterns, and application context) and continuously refines its understanding of “normal,” so simple tricks like minor header tweaks or basic IP address rotation won’t slip past it.

Bot Blockers vs. Web Scraping: How to Navigate Each?

Modern bot blockers are combining machine learning, advanced fingerprinting, and all sorts of sophisticated behavior analysis to spot scrapers in real time. 

Traditional scraping scripts, regardless of the language or stack, fail because they cannot mimic the full biometric and cryptographic profile of a human user. Even the engineering overhead required to maintain a bypasser for Akamai or DataDome can often exceed the value of the data itself. The problem then isn’t code logic, but infrastructure maintenance. 

There are also issues of ethical compliance and legal barriers that can arise. The solution is to simplify web scraping using compliant tools by letting a dedicated scraping API handle proxies, browser behavior, JavaScript rendering, and CAPTCHAs for you. 

ScraperAPI is built exactly for this use case. It gives you a single endpoint that handles complete bypassing, so you can focus on data, not defense systems.

Here is how ScraperAPI resolves the detection hurdles of each bot blocker.

Real-Time ML Blockers (DataDome, HUMAN)

Our API routes your requests through a massive pool of premium residential and mobile proxies. This ensures no single IP generates enough volume to trigger a flag. Crucially, we handle the “identity management” as well, automatically handling CAPTCHAs and managing session cookies so every request appears as a unique, legitimate user with a consistent hardware profile.

Edge and CDN-Based Systems (Akamai, Fastly, Cloudflare)

ScraperAPI manages the TLS fingerprinting and header ordering to strictly match real browser standards (like Chrome or Safari). Our global proxy network ensures your requests originate from the correct geolocations to bypass regional locks. We handle the “waiting rooms” and interstitial challenges (e.g., Cloudflare’s Turnstile) on our end, so your pipeline receives only the successful, clean HTML response.

Behavior and Fingerprint Analysis (PerimeterX)

Here, we manage the full browser lifecycle behind the scenes. From JavaScript execution and cookie persistence, injecting the necessary behavioral signals to pass humanity checks, etc. You don’t need to engineer complex mouse movements or worry about header consistency; our rendering engine ensures your request passes the behavioral audit before the data is ever sent back to you.

Cloud-Native and Open-Source Security (open-appsec, Amazon WAF)

ScraperAPI integrates seamlessly with any tech stack (Python, Node.js, Java, Ruby, Go, PHP, R) to standardize your request volume. We automatically handle retries and pace your requests to keep your scraping activity within compliant usage thresholds. This prevents your IPs from being burned by static firewall rules, allowing for consistent, long-term data extraction.

Unblock your data pipelines with ScraperAPI

Whether you’re fighting Akamai’s fingerprinting or DataDome’s device checks, maintaining a DIY bypass solution is a full-time job that drains engineering resources.

ScraperAPI simplifies that battle into a simple API call. We manage the proxies, the browsers, the CAPTCHAs, and the TLS fingerprints, so you can stop debugging multiple errors and focus on the only thing that matters: the data.

Create a free account today and get 5,000 free API credits to test our solution against your toughest targets.

For large-scale projects requiring custom unblocking strategies or higher throughput, contact our sales team to discuss enterprise options.