How does ASP.NET Core decide which endpoint handles a request?

How does routing select an endpoint in ASP.NET Core?

Explains endpoint routing, route templates, HTTP method matching, endpoint metadata, and ambiguity problems.

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ASP.NET Core matches the incoming request path and HTTP method against the endpoints registered in the app. Controllers use attributes like [HttpGet("{id}")], while minimal APIs use mappings like MapGet. The selected endpoint carries metadata such as authorization policies, filters, and parameter binding rules. If multiple routes match equally well, the app can fail with an ambiguous route problem.

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Route templates, HTTP method constraints, endpoint metadata, ambiguity, and API route design.

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Why this question matters
Routing is both framework mechanics and API contract design. A good answer explains how matching works and why route choices affect clients, authorization, OpenAPI, and future compatibility.
ASP.NET Core matches the incoming request path and HTTP method against the endpoints registered in the app. Controllers use attributes like [HttpGet("{id}")], while minimal APIs use mappings like MapGet. The selected endpoint carries metadata such as authorization policies, filters, and parameter binding rules. If multiple routes match equally well, the app can fail with an ambiguous route problem.
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In practice, I design routes around resources and clear operations. For example, reads one order and filters the collection. The trade-off is that very clever routes can become hard to maintain, so I prefer explicit route templates and predictable conventions. I also check how routes appear in OpenAPI docs and how they interact with authorization policies.

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Creating overlapping route templates.
Using verbs in every route instead of resource-oriented design.
Forgetting route constraints for IDs, slugs, or enums.
Designing routes that make versioning awkward.
Ignoring how routes appear in OpenAPI.

How does ASP.NET Core decide which endpoint handles a request?

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