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The Complete Guide to Handling 403 Errors When Scraping

As a seasoned web scraping veteran, I‘ve helped hundreds of clients debug and overcome those pesky 403 forbidden access errors. From e-commerce sites to social media platforms, these access denied messages can grind your scraping efforts to a halt.

But fear not! With the right strategies and scraping etiquette, you can circumvent bot blocks and resume scraping with minimal interruptions. This comprehensive guide will give you a complete understanding of 403 errors, why they happen, how to avoid triggers, and smart techniques to prevent your scraper from being labeled a bot and denied access.

Whether you‘re scraping for market research, monitoring prices, compiling news articles, or aggregating social data – you need to scrape smarter to scrape longer. Follow these tips and treat websites respectfully to keep the content flowing!

What Exactly is a 403 Status Code?

When you attempt to programmatically retrieve content from a URL and get back a 403 error, it means the server has denied your access to that resource.

These errors are incredibly common when scraping or crawling websites, hence why I encounter them on a daily basis!

According to the HTTP standard RFC 7231, the 403 status code means:

"The server understood the request, but is refusing to fulfill it."

In other words, the website recognized what you were asking for, but has explicitly blocked you from accessing that content. This is different from a 404 error, where the page simply couldn‘t be found.

403 errors can happen on public pages and sections of sites that are normally visible to anyone. The key distinction is that the site has identified your script or bot and labeled it unwanted traffic.

Some key facts about 403 forbidden codes:

  • They indicate denial of access to a web page or endpoint that normally exists.
  • 403s are very common when sites detect scraping or crawling attempts.
  • You‘ll get a 403 even on public pages if flagged as a bot.
  • A 403 doesn‘t mean the site is down – you are just blocked from accessing it programmatically.

When you encounter a 403 in web scraping activities, it means one of your scrapers has likely been detected and flagged as malicious or abusive. But with the right approach, you can turn things around quickly!

Why Do 403 Errors Happen When Scraping or Crawling Sites?

There are range of reasons you could suddenly start getting 403 access denied messages when your scrapers were previously functioning fine:

Your Scraper Has Been Identified as a Bot

The most common trigger is that your web scraping tool or script has been detected by the site‘s bot mitigation defenses. Clever bot protection services analyze visitor patterns and behaviors to label scrapers.

Once identified, you‘ll be served 403s to block automated access. Some common "tells" they look for:

  • Request User-Agent – Looks robotic rather than a real device
  • High request frequency – No human clicks that fast!
  • Repeated predictable paths – Sign of a scripted crawler
  • No mouse movements or scrolling – Bots don‘t interact like humans

You‘re Missing Required Headers, Cookies, or Credentials

Modern websites implement authorization tokens, CSRF protections, and other validation requirements in headers and cookies. If your scraper is not properly handling these:

Cookie: sessionId=8y349hf98dhf
Authorization: Bearer ksjdhf8y3489hf

And instead making plain requests like:

GET /products

You will frequently run into 403 access errors, since the backend expects certain headers and cookies to allow access.

You‘re Sending Too Many Requests Too Quickly

If your scraper is pounding a site with a huge volume of rapid requests, you can easily trigger protections for abuse and bandwidth limit violations.

I‘ve seen cases where reasonable request levels (e.g. 8/sec) worked fine, but spiking traffic to 50/sec or 100/sec triggered immediate 403 rate limiting and blocks. Slow down!

The Site‘s Layout or Logic Has Changed

Websites regularly change URLs, page structures, required parameters, and access control logic. If you haven‘t updated your scraper, suddenly it will start generating invalid requests and 404/403 errors.

For example, a product URL that was previously:


Might change to:


Your scraper needs to monitor and adapt to site changes to avoid hiccups.

Troubleshooting the Cause of 403 Errors

When you start seeing 403 forbidden messages, how do you know exactly what triggered it? Here are some troubleshooting tips:

Check your headers – Inspect the headers your scraper is sending. Do they look like a real browser? Are you missing any required Cookies or tokens that could cause authentication failures?

Review recent changes to the site – Has the site changed URLs, page structures, or login processes recently that could now be breaking your scraper logic?

Check your IPs – Are all requests coming from a small pool of known scraper IPs? Varying IPs helps avoid blocks.

Look for rate limiting – Is there a spike in traffic that could have crossed a volume threshold? Check for rate limit warnings.

Read your user agent – Does your scraper identify obviously as a script or bot vs mimicking a real browser?

Check for new UI features – Did the site add new intermediate pages, popups or interstitials that may be hindering your scraper?

Is JavaScript required? – Does the site now rely on JavaScript to render page content that your script isn‘t executing?

With a bit of focused troubleshooting, you can usually identify what triggered the 403s and take steps to resolve it.

Strategies to Avoid 403 Errors When Scraping Sites

Once you understand the cause of those pesky 403 access denied errors, here are some proven techniques to avoid and overcome them:

Use Proxies and Rotate IPs Frequently

One of the best ways to mask scraper traffic is to route requests through residential proxy services or pools of IPs. By scraping through different IPs, you appear more like many real users than one aggressive bot.

Important tips when using proxies:

  • Fully randomize and rotate IPs with each request – no patterns.
  • Use geo-distributed proxies from different regions.
  • Always scrape via SSL for encryption.
  • Authenticate proxies to avoid anonymity flags.
  • Avoid poor quality, slow, banned or suspicious proxies.

With robust, reliable, well-managed proxies, you can cloak your scraping activities and avoid tripping bot triggers.

Introduce Random Time Delays Between Requests

No human sits clicking links hundreds of times per minute. By introducing randomized delays in your scraper, you can throttle traffic to natural human levels.

  • Add 2-7 second random delays between requests.
  • Occasionally insert longer 15-30 second delays.
  • Scrape pages in a fully randomized order – no patterns.

This helps greatly reduce volume and bot signals to avoid crossing thresholds.

Spoof and Randomize User Agents

Most scrapers have very conspicuous user agents like:

Mozilla/5.0 (compatible; Googlebot/2.1; +

Or other robotic identifiers. Sites look for these!

Instead, spoof real desktop and mobile browser user agents like:

Mozilla/5.0 (Windows NT 10.0; Win64; x64) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/74.0.3729.169 Safari/537.36

Mozilla/5.0 (iPhone; CPU iPhone OS 13_3 like Mac OS X) AppleWebKit/605.1.15 (KHTML, like Gecko) Version/13.0.4 Mobile/15E148 Safari/604.1 

Rotate randomly between many real user agents to appear like different devices.

Check for and Handle Required Headers, Cookies, Tokens

As discussed above, missing authentication headers and cookies is a common trigger for 403 errors.

When scraping modern sites, always:

  • Inspect headers from real browsers to identify requirements.
  • Extract tokens and session keys programmatically.
  • Re-check and handle cookies and headers before each request.

Handling these properly helps you seamlessly authenticate just like a real user browsing the site.

Monitor Sites for Changes

Don‘t just set and forget your scrapers! Websites regularly change structure, URLs, and access controls.

To avoid hiccups:

  • Occasionally scrape sample areas to check for issues.
  • Follow site change logs and announcements.
  • Build scrapers in a modular, maintainable way.
  • Adjust to new requirements as they arise.

Keeping scrapers flexible prevents breakage when sites evolve.

Consider Using Headless Browsers

Tools like Selenium and Playwright allow you to programmatically drive real Chrome, Firefox and WebKit browser instances.

Because these emulate a real browsing environment, they can bypass some basic bot blocks.

Downsides are complexity and lower throughput. But they‘re robust options when your scripts hit walls.

Seek Permission from Site Owners

When possible, it can be worthwhile to directly reach out the website owner and explain your data scraping needs. Many are willing to whitelist applications generating valuable insights without harm.

Be fully transparent about:

  • Who you are
  • What data you need to access
  • How it will be used

Often sites will grant limited access or work to find a mutual win rather than just blocking arbitrarily.

Back Off Exponentially, Don‘t Retry Aggressively

When your scraper hits spikes in 403 errors, back off. Limit retry attempts and use exponential back off waiting increasing amounts of time between retries.

Aggressive rapid retries will only exacerbate limits and get you blocked faster. Slow down and wait patiently if hitting issues.

Web Scraping Best Practices to Maintain Access

Beyond specific countermeasures, following general web scraping best practices will help avoid crossing lines into unwanted bot territory:

Limit Overall Request Volume

Only scrape data you actually need, when you need it. Don‘t recklessly pull down entire sites if you only require small slices of content. Moderation is key for ongoing access.

Distribute Requests Over Multiple Proxies and IPs

Don‘t bottleneck all your traffic through a few IPs. Spread it out over a large, distributed pool of proxies from different providers and regions.

Vary User Agents with Every Request

Use random user agent spoofing to give the impression of many real visitors, not automation.

Implement Polite Scraping Etiquette

Use delays, honor robots.txt, back off when issues arise. Fast aggressive scraping raises red flags. Take it slow.

Solve CAPTCHAs and Handle Other Challenges

Leverage services to bypass CAPTCHAs and phone verification steps when possible.

Obtain Site Owner Permission

Build trust through transparency about your needs. Many will provide API access if you ask nicely!

What Happens If You Ignore those 403 Errors?

It can be tempting to disregard sporadic 403 errors, but this opens up significant risks, such as:

  • Permanent IP bans – Ignoring blocks can escalate to full blacklisting of your IPs.

  • Wasted resources – You‘ll burn resources and time trying blocked IPs and proxies.

  • Loss of data – Your scrapers will miss new content and updates.

  • Legal action – Copyright and CFAA allegations can arise from unauthorized access.

  • Reputational damage – You or your company may get labeled "bad actors".

The stakes are high! Stay attentive and respond quickly to 403s. Don‘t give sites a reason to drop the banhammer.

In Closing – Overcoming 403s for Smooth Scraping

HTTP 403 errors are a fact of life when running scrapers to harvest web data. But they don‘t need to kill your crawlers! With a smart, polite approach you can avoid crossing the line into unwanted bot territory and continue collecting the data you need.

Now you‘ve got a complete understanding of what causes those pesky access denied messages, as well as proven techniques to minimize and recover from them quickly when they occur:

  • Troubleshoot triggers
  • Use proxies
  • Add delays
  • Monitor sites
  • Scrape respectfully

Follow the strategies I‘ve compiled based on hundreds of successful scraping projects, and you‘ll be prepared to overcome 403 errors and keep your scrapers chugging smoothly!

Need personalized help solving your specific web scraping errors and blocks? Just reach out! I offer affordable consulting to get your scrapers back up and running, no matter how complex the site.

Happy hassle-free scraping!

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