Definition
NLWeb is an open specification for adding a natural language interface to a website. Introduced by Microsoft in 2025 under the direction of R.V. Guha—who previously worked on RSS and Schema.org—it lets a site expose a conversational endpoint that agents can query directly, rather than forcing every AI system to crawl, render, and infer structure from HTML built for human eyes.
The interface is intentionally small. An ask method submits a natural language request, and an await method handles long-running work, with responses returned as structured objects and optional streaming over server-sent events. NLWeb is transport-agnostic: the same JSON structures work over HTTP, WebSockets, or inside MCP, which means an NLWeb endpoint can effectively function as an MCP server for the site.
Conceptually NLWeb continues the lineage of structured content formats. Schema.org told crawlers what an entity was; llms.txt told AI systems which content mattered; NLWeb lets the site answer questions about itself. Sites already publishing good schema markup have a head start, since that structured data is what an NLWeb endpoint typically serves.
For GEO teams the appeal is control and fidelity. When an agent retrieves through a site's own endpoint, the site decides what is returned, keeps inventory and pricing current, and avoids the misreadings that come from parsing rendered pages. The trade-off is that adoption is still early and uneven, so an NLWeb endpoint supplements—rather than replaces—the fundamentals of being crawlable, structured, and citable.
Examples of NLWeb
- A retailer exposes an NLWeb endpoint so agents can ask about stock and sizing directly instead of scraping product pages.
- A documentation site serves its existing schema data through NLWeb, letting assistants answer version-specific questions accurately.
- An agent queries a site's NLWeb endpoint over MCP and receives structured results rather than rendered HTML.
- A publisher uses NLWeb streaming responses so an assistant can start summarizing an answer before the full result set is assembled.
