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Web data access

Every web data project starts with the same problem: turning a URL into content you can actually use. That means choosing between an HTTP request and a real browser, getting served at all when a site would rather not, discovering URLs you do not have yet, and keeping the whole thing running when you move from ten pages to ten million. The terms below cover how pages get fetched, why sites refuse them, the proxy infrastructure that changes that answer, how crawlers find URLs in the first place, and what breaks when volume goes up.

Getting blocked

How do websites detect web scrapers? Websites compare what your request claims to be against what it demonstrably is, and flag the mismatches, from the TLS handshake up to the rhythm of your browsing. How do you bypass CAPTCHAs when scraping? Stop the challenge from being issued, by making the request look like an ordinary visitor across IP, TLS, headers and fingerprint, rather than trying to answer a challenge after it appears. What is a CAPTCHA solver? A CAPTCHA solver is a service that receives a challenge a site has already issued and returns an answer token, either from a model or from a person working through a queue. What is a JavaScript challenge? A JavaScript challenge is an interstitial page that runs code in your browser and only serves the real content once that code returns a valid result, which filters out clients that do not execute JavaScript. What is a web application firewall? A WAF inspects HTTP traffic before it reaches an application and blocks requests matching known attack patterns, which is why scrapers sometimes get refused by a rule that was never aimed at them. What is an anti-bot system? An anti-bot system is a layer in front of a website that scores each request on network, browser and behavioural signals, then serves, challenges or blocks it based on that score. What is an anti-detect browser? An anti-detect browser is a modified browser that presents a controllable, internally consistent fingerprint, so each profile it runs looks like a separate ordinary machine. What is browser fingerprinting? Browser fingerprinting identifies a visitor by combining dozens of properties their browser reveals, such as fonts, screen size, graphics rendering and timezone, into a signature that stays stable without needing a cookie. What is protected web access? Protected web access means reaching pages that sit behind anti-bot protection, where an ordinary HTTP request gets a block page instead of the content. What is TLS fingerprinting? TLS fingerprinting identifies your client from the exact contents and ordering of its encryption handshake, which happens before any HTTP header is sent and cannot be changed by setting a user agent.

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