Anyone can parse HTML. Keeping connections open, undetected, and cost effective is where senior scraper engineering pays off. The ground truth lives in network behavior and the web’s actual distribution of protocols, not hunches. Build to the numbers and your pipeline becomes durable instead of brittle.
Modern pages are locked behind encryption, inspected by CDNs, and assembled by client JavaScript. That means success hinges on how your traffic looks on the wire, how your IP space is perceived, and how your fetch stack handles concurrency. Below is a blueprint anchored in measurable web realities rather than folklore.
What the numbers mean for your scraper
If the target advertises HTTP/2, prefer it. Multiplex a small set of connections per origin rather than fanning out dozens of short lived sockets. This cuts handshake overhead and better mirrors real browsers. TLS 1.3 completes in one round trip while TLS 1.2 needs two. Favor 1.3 where offered and enable session resumption to reduce latency on repeat fetches.
Mirror browser ALPN and cipher suites. Mismatched TLS stacks are a strong heuristic for anti bot systems. Keep HTTP semantics consistent too, including header casing, pseudo header order on HTTP/2, and accept encodings that match real clients.
IP reputation and network origin
CDNs heavily weight IP origin. Clean, diverse ASNs behave very differently from concentrated data center blocks. Rotating among subnets that appear residential or consumer broadband reduces false positives. An ISP proxies provider can supply routes that align with real last mile patterns while preserving session stability.
Plan allocation by target. Heavily protected domains deserve stickier sessions from smaller pools to accumulate good reputation. Static assets and low risk endpoints can use broader rotation. Measure block rates per ASN and recycle any ranges that accrue soft blocks or challenges.
JavaScript heavy sites and resource budgeting
With 98% of sites running JavaScript, decide page by page whether to execute or simulate. Headless engines handle hydration and dynamic routes but cost CPU and memory. Where the network calls are predictable, calling the same JSON endpoints is faster and less visible. Cache script signatures and reuse precomputed render paths to avoid booting full runtimes for every URL.
Dual stack awareness
Given the scale of IPv6 adoption, enabling dual stack expands capacity and reduces collision with abused IPv4 pools. Some targets prioritize IPv6 paths differently at the CDN layer. Track success rates separately for v4 and v6, and route accordingly.
Mobile first targeting
With most page views on mobile, many sites optimize for smaller viewports and defer content differently. Maintain real mobile client profiles, including user agent, viewport metrics, and network hints. When a property gates content by device type, a mobile profile often reaches simpler markup and lighter API calls.
Practical checklist for reliable collection
To optimize web scraping, negotiate HTTP/2 where available and reuse a few long-lived connections per origin, while adopting TLS 1.3 with session resumption and browser-realistic cipher suites. Track block rates by ASN, not just IP, and retire noisy ranges quickly. Split traffic by risk, using sticky sessions for protected paths and broad rotation for static assets. Decide whether to render or simulate per route by measuring cost and coverage. Enable IPv6 and compare success metrics between v4 and v6, maintaining distinct desktop and mobile client profiles with accurate headers and hints. Instrument every request for status codes, challenge rates, and handshake timing, feeding this data back into routing decisions. Scraping pipelines fail when they ignore how the web is actually delivered; therefore, design for encrypted transports, multiplexed connections, CDN scoring, and client-side execution. Anchor decisions to these metrics, keep tight feedback loops on block signals, and your crawler will resemble normal traffic where it matters most.
