The owner of the technical blog Wandering Thoughts (part of the CSpace wiki) has implemented a defensive measure familiar to many web operators in 2025: aggressively blocking HTTP requests bearing generic or suspicious User-Agent headers. This move, explicitly attributed to combating a "plague of high volume crawlers" feeding Large Language Model (LLM) training datasets, underscores a growing infrastructure challenge.

The Trigger: Indiscriminate Scraping for AI

The blog owner states bluntly: "as of early 2025 there's a plague of high volume crawlers (apparently in part to gather data for LLM training) that behave like this." The sheer volume and often poorly configured nature of these crawlers – frequently using extremely generic identifiers like Go-http-client/1.1 – forces resource-constrained site operators into defensive postures.

"All HTTP User-Agent headers should clearly identify what they are, and for non-browser user agents, they should identify not just the software involved but also who specifically is using that software."

This stance reflects a hardening attitude. Generic User-Agents, once merely a minor annoyance, are now seen as inherently suspicious and potentially indicative of automated scraping operations lacking proper attribution or respect for robots.txt directives.

Collateral Damage for Developers

The blog notice explicitly addresses users encountering the block – often developers or sysadmins running custom scripts, CLI tools (like curl without a custom UA), or niche applications. The message implies these legitimate users are unintended casualties caught in a necessary defensive action against unsustainable bot traffic. This highlights a practical problem: distinguishing between malicious/abusive crawlers and benign automation is increasingly difficult at scale.

The Bigger Picture: Web Infrastructure Under Siege

This individual blog's policy is a microcosm of a widespread issue:

  1. Resource Drain: LLM-focused crawlers consume significant bandwidth and server resources, impacting site performance and operational costs for independent operators.
  2. Opaque Operations: Many crawlers provide minimal identification, making it hard to contact operators or understand their scraping policies.
  3. The Attribution Imperative: The demand for detailed User-Agent strings (software + responsible entity) signals a push for accountability in web scraping activities.
  4. Escalating Defenses: Blocking based on User-Agent is a blunt instrument, but often a necessary first line of defense when facing overwhelming, poorly behaved traffic.

Implications for the Ecosystem

  • Developers & DevOps: Custom scripts and tools using default HTTP libraries are increasingly likely to be blocked. Best practice now demands setting a unique, descriptive, and contact-inclusive User-Agent string.
  • LLM Training Pipelines: Reliance on indiscriminate web scraping faces growing technical friction, potentially pushing the industry towards more structured data acquisition methods or formal agreements with content providers.
  • The Open Web: The tension between accessibility and sustainability intensifies. Can the open web model survive if every independent publisher needs to erect significant barriers against resource-hungry AI data harvesting? The notice on Wandering Thoughts is a small but telling sign of the strain.

The silent blockade implemented by this single blog serves as a stark reminder: the infrastructure of the open web is groaning under the weight of the AI gold rush, and developers are finding themselves on both sides of the barricades.