Best User Agent for Scraping: Essential Practices in 2025

The web in 2025 is a wild place—half the traffic isn’t even human anymore. That’s right, bots now account for nearly , and anti-bot systems are fighting back harder than ever. As someone who’s spent years building automation tools and scraping workflows, I’ve seen firsthand how a single misstep—like using the wrong user agent—can turn your data project into a digital faceplant. For sales, ecommerce, and operations teams, getting blocked by a website isn’t just annoying; it can mean missed leads, outdated pricing, or lost revenue.

But here’s the good news: you don’t need to be a technical wizard to beat these defenses. In this guide, I’ll break down why user agent strategy is now mission-critical for scraping, how to avoid rookie mistakes, and how makes user agent management so simple you might forget it’s even there. Whether you’re scraping for leads, monitoring SKUs, or just trying to keep your spreadsheets fresh, this is your playbook for staying one step ahead.

Why Choosing the Best User Agent for Scraping Matters

Let’s start with the basics: what is a user agent? Think of it as your browser’s “ID card.” Every time you visit a website—whether you’re a human or a bot—your browser sends a User-Agent string in the request headers. It’s a little intro that says, “Hi, I’m Chrome on Windows,” or “I’m Safari on iPhone” (). Here’s what a typical Chrome user agent looks like:

1Mozilla/5.0 (Windows NT 10.0; Win64; x64) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/120.0.0.0 Safari/537.36

Websites use this information for two big reasons:

1. To serve the right content (like mobile vs. desktop layouts).
2. To spot bots and scrapers.

If your user agent says “python-requests/2.28.1” or “Scrapy/2.9.0,” you might as well be wearing a “Hello, I’m a bot!” name tag. Sites keep blocklists of these obvious identifiers, and they’ll slam the door on you faster than you can say “403 Forbidden.” On the flip side, using a mainstream, up-to-date browser user agent helps you blend in with the crowd.

In short: your user agent is your disguise. The better the disguise, the more likely you are to get the data you need.

The Role of User Agent in Web Scraping Success

Why does user agent selection have such a huge impact? Because it’s the first line of defense for most anti-bot systems. Here’s what can go wrong if you get it wrong:

• Instant blocks (403/429 errors): Use a default scraping library UA, and you’ll get blocked before you even see the homepage ().
• Empty or fake data: Some sites serve up blank or “dummy” pages to suspicious user agents.
• CAPTCHAs or redirects: A bot-like UA triggers “Are you human?” challenges or endless login loops.
• Throttling and bans: Hit a site with the same UA over and over, and you’ll get throttled or IP banned.

Let’s see how different user agents play out:

The lesson? Pick your disguise wisely. And don’t forget—modern anti-bot systems don’t just look at your user agent. They check if your other request headers (like Accept-Language or Referer) match up. If you claim to be Chrome but don’t send the right headers, you’ll still get caught ().

Here’s where Thunderbit comes in. I’ve talked to so many business users—sales reps, ecommerce managers, real estate agents—who just want the data, not a crash course in HTTP headers. That’s why we built Thunderbit to make user agent management invisible and automatic.

Thunderbit: Simplifying User Agent Management for Everyone

With Thunderbit’s , you don’t have to pick a user agent at all. Our AI engine does it for you, choosing the most realistic, up-to-date browser signature for every site. Whether you’re using the (which literally uses Chrome’s real UA) or cloud scraping (where our AI rotates through a pool of current browser UAs), you’re always blending in with normal traffic.

And it’s not just about the user agent. Thunderbit sends a full, consistent set of headers—Accept-Language, Accept-Encoding, Client Hints, you name it—so your requests look and act like a real browser. No more mismatched headers, no more “bot” red flags.

The best part? You don’t have to configure anything. Thunderbit’s AI handles all the technical details behind the scenes, so you can focus on what matters: getting reliable, high-quality data.

Why Dynamic User Agent Rotation Is a Must-Have Best Practice

Let’s say you find the perfect user agent. Should you just use it for every request? Not so fast. In 2025, using the same UA over and over is a dead giveaway. Real users have different browsers, versions, and devices. If your scraper hits a site 500 times in a row with the same UA, it’s like sending in a parade of identical twins—nobody’s fooled.

That’s why dynamic user agent rotation is now industry standard. The idea is simple: rotate through a list of realistic, up-to-date user agents for each request or session. This makes your scraper look like a diverse group of real visitors, not a single automation script ().

Thunderbit’s AI-driven rotation takes this a step further. For multi-page crawls or scheduled jobs, Thunderbit automatically rotates user agents and even pairs them with different proxy IPs. If a site starts getting suspicious, Thunderbit adapts in real time—switching UAs, adjusting headers, or slowing down requests as needed. All of this happens behind the scenes, so your scraping stays undetected and your data keeps flowing.

User Agent and Request Headers: The Power of Consistency

Here’s a pro tip: user agent is just one piece of your request’s “fingerprint.” Modern anti-bot systems check if your UA matches up with other headers like Accept-Language, Accept-Encoding, and Referer. If you claim to be Chrome on Windows but send a French Accept-Language from a New York IP, that’s a red flag ().

Best practice:

• Always send a full set of headers that match your user agent.
• Keep Accept-Language and Accept-Encoding consistent with your UA and (if possible) your IP geolocation.
• Use browser developer tools to inspect real requests and copy the full header set for your chosen UA.

Thunderbit handles all of this for you. Our AI ensures every request is a perfect match—user agent, headers, and even browser fingerprinting. You get a human-like request profile without lifting a finger.

Avoiding Common Pitfalls: What NOT to Do with User Agents

I’ve seen a lot of scraping projects fail for the same reasons. Here are the biggest mistakes to avoid:

• Using default scraping library UAs: Strings like python-requests/2.x, Scrapy/2.9.0, or Java/1.8 are instant block triggers.
• Outdated browser versions: Claiming to be Chrome 85 in 2025? Suspicious. Always use current browser versions.
• Mismatched headers: Don’t send a Chrome UA with missing or mismatched Accept-Language, Accept-Encoding, or Client Hints.
• Known crawler UAs: Anything with “bot,” “crawler,” “spider,” or tool names (like AhrefsBot) is a red flag.
• Blank or gibberish UAs: Sometimes allowed, but often suspicious and unreliable.

Quick checklist for safe user agents:

• Use real, up-to-date browser UAs (Chrome, Firefox, Safari).
• Rotate through a pool of UAs.
• Keep headers consistent with your UA.
• Update your UA list monthly (browsers update fast).
• Avoid anything that screams “automation.”

Thunderbit in Action: Real-World Scenarios for Sales and Operations

Let’s get practical. Here’s how Thunderbit’s user agent management helps real teams:

One sales team using Thunderbit scraped thousands of websites for leads and saw only ~8% email bounce rate—compared to 15–20% from purchased lists (). That’s the power of fresh, human-like scraping.

Step-by-Step: How to Scrape with the Best User Agent Using Thunderbit

Here’s how easy it is to get started with Thunderbit—no technical skills required:

1. Install the .
2. Navigate to your target website. Log in if needed—Thunderbit works on logged-in pages too.
3. Click “AI Suggest Fields.” Thunderbit’s AI scans the page and suggests the best columns to scrape.
4. Review and adjust fields if you want. Rename, add, or remove columns as needed.
5. Click “Scrape.” Thunderbit extracts the data, rotating user agents and headers behind the scenes.
6. Export your data. Send it straight to Excel, Google Sheets, Airtable, Notion, or download as CSV/JSON.

No need to pick or update user agents—Thunderbit’s AI does it all, adapting to each site for maximum success.

Comparing Thunderbit with Traditional User Agent Management

Let’s see how Thunderbit stacks up against the old-school, manual approach:

Thunderbit is built for anyone who wants reliable, scalable scraping—without the technical baggage.

Key Takeaways: Building a Future-Proof User Agent Strategy

Here’s what I’ve learned (sometimes the hard way) about user agent management in 2025:

• Never use default or outdated user agents. They’re the #1 reason scrapers get blocked.
• Rotate user agents dynamically. Diversity is your friend—don’t let your scraper look like a robot parade.
• Keep headers consistent and realistic. Your user agent is only as good as the company it keeps.
• Stay up to date. Browser versions change fast; so should your UA list.
• Let AI handle the hard stuff. Tools like Thunderbit bake best practices right in, so you can focus on results, not requests.

If you’re tired of getting blocked, troubleshooting scripts, or just want to scrape like a pro without the hassle, . Our AI web scraper is trusted by thousands of users worldwide and is designed to make web data accessible to everyone—no technical headaches required.

For more tips, tutorials, and deep dives into web scraping, check out the .

FAQs

1. What is a user agent, and why does it matter for web scraping?
A user agent is a string sent with every web request that identifies your browser and operating system. Websites use it to serve the right content and spot bots. Using the right user agent helps your scraper blend in and avoid blocks. 2. Why shouldn’t I use the default user agent from my scraping library?
Default user agents like python-requests/2.x are well-known bot signatures and are often blocked instantly. Always use realistic, up-to-date browser user agents. 3. How does Thunderbit handle user agent rotation?
Thunderbit’s AI automatically rotates through a pool of current, realistic browser user agents for each request or session. This makes your scraping look like real, diverse user traffic. 4. Do I need to set headers like Accept-Language or Referer manually with Thunderbit?
Nope! Thunderbit’s AI ensures all headers are consistent and match your user agent, so your requests look and act like a real browser. 5. What happens if a site starts blocking my requests anyway?
Thunderbit detects blocks or CAPTCHAs and adapts in real time—switching user agents, adjusting headers, or retrying as needed. You get reliable data without the manual troubleshooting.

Ready to scrape smarter? and let our AI handle the user agent cat-and-mouse for you. Happy scraping!

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