WebP was formally specified in which RFC in November 2024?

WebP was formally specified in RFC 9649, published in November 2024.

RFC 9649 is titled “WebP Image Format” and is an Informational RFC from the Internet Engineering Task Force. It defines the WebP image format and registers its media type, documenting the container and image technologies that had already become widely used in software and on the web.

WebP is built around the RIFF container and can support both lossy and lossless compression, transparency, and animation. Its lossy format is associated with the VP8 bitstream, while its lossless format uses a separate WebP lossless bitstream. A WebP file commonly begins with a RIFF signature and identifies its format with the WEBP brand.

The RFC number is easy to confuse with older image-related standards. RFC 2083 specifies PNG, while RFC 8259 specifies JSON; neither formally specifies WebP. RFC 9649 is also Informational rather than Internet Standards Track, so “formally specified” does not mean that WebP became a mandatory web standard. The RFC records and standardizes the format’s technical definition and media-type registration.