yarlpattern vs. aiohttp.web.UrlDispatcher

The aio-libs ecosystem already ships a mature URL pattern matcher in aiohttp.web.UrlDispatcher — stable since 2016, used by every aiohttp web service in production. The two tools have different scopes and are best at different jobs.

	aiohttp.web.UrlDispatcher	yarlpattern
Spec lineage	path-to-regexp (Flask / Werkzeug family)	WHATWG URLPattern Standard
Pattern syntax	{name} / {name:regex}	:name / :name(regex) / * / {group}?
Matches against	Path component only — protocol / host / port are determined by the running web server	All eight URL components: protocol, hostname, port, pathname, search, hash, username, password
Operating mode	Dispatch-oriented: register routes with handlers; route an incoming request to them	Predicate-oriented: compile a pattern, ask .test(url) or .exec(url)
Standalone use	The class is technically usable outside aiohttp, but its API is shaped around request handling	The pattern is the API; no server context needed
Cross-language portability	Python-specific syntax	Same pattern string works in browsers, Deno, Bun, Cloudflare Workers

If you're building an aiohttp web service, use UrlDispatcher. If you're matching URLs outside a server context (crawler, classifier, analytics pipeline, CLI), or you need to constrain on hostname / port / scheme alongside path, or you want patterns that match what browsers implement, yarlpattern is the closer fit.