Chromium now recognizes all valid JSON MIME types as defined by the WHATWG mimesniff specification. This includes any MIME type whose subtype ends with “+json”, in addition to the traditional application/json and text/json. This change ensures that web APIs and features relying on JSON detection behave consistently with the web platform standard and other browsers. A key motivation for this change is to fix JSON module import behavior, where previously valid JSON MIME types like text/html+json and image/svg+json would fail to load as modules. Draft CL: https://chromium-review.googlesource.com/c/chromium/src/+/6525687 Related Issues: https://github.com/whatwg/mimesniff/issues/112. The consensus was to retain the broad definition of JSON MIME types—including all */*+json.
Without this change, developers must rely on inconsistent MIME sniffing behavior across browsers, which can lead to incorrect content handling. Aligning with the spec ensures predictable behavior and improves interoperability.