application/zstd

Meta's compressor that made the speed-versus-ratio trade-off mostly obsolete: gzip-class ratios at many times the throughput, standardized as RFC 8878 along with this media type. Send application/zstd for a .zst file itself; for compressed HTTP responses use Content-Encoding: zstd instead, which browsers began accepting in 2024 — mixing the two up hands users a file they did not ask to have decompressed, or one they cannot open. The frame magic was deliberately chosen to avoid bytes that could open a text file, so sniffers rarely misfire on it.

.zst is the convention on disk, though the registry carries no extension mapping for this type.

Defined by RFC 8878 · IANA registration. Registry facts from the IANA media-types registry via mime-db.