IANA Protocol Registries
IANA
Specs define behavior; IANA registries define the allowed code points. Wrong port or MIME type? Check here.
What It Is
Authoritative registries for protocol parameters: ports, HTTP codes, media types, DNS record types, TLS extensions, RTP payload types, URI schemes, and hundreds more.
Taxonomy
Alphabetical A–Z index grouped by protocol name
Top-Level Categories
Master Catalog
Authoritative registry for protocol parameters: ports, HTTP status codes, media types, DNS record types, and many other code points. Not a spec body — a registry body.
View all bodies →Curated specs from IANA
Correct Content-Type headers drive content negotiation, browser rendering, and API behavior. Wrong types cause security and parsing bugs.
Every upload, download, attachment, and asset pipeline crosses these layers. Misunderstanding header vs envelope causes MIME spoofing bugs, parser differentials, and broken file validation. Start here before diving into individual format specs.
Extension spoofing (`virus.exe` → `photo.jpg`) and MIME spoofing are common attack vectors. Magic-byte detection is the first line of defense in upload validation, antivirus, and content sniffing.