The "X25519" algorithm provides tools to perform key agreement using the X25519 function specified in [RFC7748]. The "X25519" algorithm identifier can be used in the SubtleCrypto interface to access the implemented operations: generateKey, importKey, exportKey, deriveKey and deriveBits.
The lack of a native implementation of the X25519 key agreement algorithm in Chrome's WebCrypto APIs forces web developers to rely on external libraries in order to get the advantages of the secure curves like Curve25519. In addition to wasting bandwidth shipping algorithms that are already included in browsers that implement TLS 1.3, this practice also has security implications, e.g. side-channel attacks as studied by Daniel Genkin et al.
Docs: https://github.com/WICG/webcrypto-secure-curves/blob/main/explainer.md https://docs.google.com/document/d/1fDTUY3HVAXehi-eSfbi7nxh8ZPw4MpSKM8U1fMdqJlU/edit?tab=t.0#heading=h.9w6b5q5ro96v
Samples: https://github.com/WICG/webcrypto-secure-curves/blob/main/explainer.md