The Fossil /doc page uses filename suffixes and the following tables to guess at the appropriate mimetype for each document. Mimetypes may be customized and overridden using the mimetypes config setting.

Default built-in mimetypes

SuffixMimetype
aiapplication/postscript
aifaudio/x-aiff
aifcaudio/x-aiff
aiffaudio/x-aiff
arjapplication/x-arj-compressed
asctext/plain
asfvideo/x-ms-asf
asxvideo/x-ms-asx
auaudio/ulaw
avivideo/x-msvideo
batapplication/x-msdos-program
bcpioapplication/x-bcpio
binapplication/octet-stream
bmpimage/bmp
bz2application/x-bzip2
bzipapplication/x-bzip
ctext/plain
cctext/plain
ccadapplication/clariscad
cdfapplication/x-netcdf
classapplication/octet-stream
codapplication/vnd.rim.cod
comapplication/x-msdos-program
cpioapplication/x-cpio
cptapplication/mac-compactpro
cstext/plain
cshapplication/x-csh
csstext/css
csvtext/csv
dcrapplication/x-director
debapplication/x-debian-package
dibimage/bmp
dirapplication/x-director
dlvideo/dl
dmsapplication/octet-stream
docapplication/msword
docxapplication/vnd.openxmlformats-officedocument.wordprocessingml.document
dotapplication/msword
dotxapplication/vnd.openxmlformats-officedocument.wordprocessingml.template
drwapplication/drafting
dviapplication/x-dvi
dwgapplication/acad
dxfapplication/dxf
dxrapplication/x-director
epsapplication/postscript
etxtext/x-setext
exeapplication/octet-stream
ezapplication/andrew-inset
ftext/plain
f90text/plain
flivideo/fli
flvvideo/flv
gifimage/gif
glvideo/gl
gtarapplication/x-gtar
gzapplication/x-gzip
htext/plain
hdfapplication/x-hdf
hhtext/plain
hqxapplication/mac-binhex40
htmtext/html
htmltext/html
icex-conference/x-cooltalk
icoimage/vnd.microsoft.icon
iefimage/ief
igesmodel/iges
igsmodel/iges
ipsapplication/x-ipscript
ipxapplication/x-ipix
jadtext/vnd.sun.j2me.app-descriptor
jarapplication/java-archive
jpeimage/jpeg
jpegimage/jpeg
jpgimage/jpeg
jstext/javascript
jsonapplication/json
karaudio/midi
latexapplication/x-latex
lhaapplication/octet-stream
lspapplication/x-lisp
lzhapplication/octet-stream
mtext/plain
m3uaudio/x-mpegurl
mantext/plain
markdowntext/x-markdown
mdtext/x-markdown
meapplication/x-troff-me
meshmodel/mesh
midaudio/midi
midiaudio/midi
mifapplication/x-mif
mimewww/mime
mjstext/javascript
mkdtext/x-markdown
movvideo/quicktime
movievideo/x-sgi-movie
mp2audio/mpeg
mp3audio/mpeg
mp4video/mp4
mpevideo/mpeg
mpegvideo/mpeg
mpgvideo/mpeg
mpgaaudio/mpeg
msapplication/x-troff-ms
mshmodel/mesh
ntext/plain
ncapplication/x-netcdf
odaapplication/oda
odpapplication/vnd.oasis.opendocument.presentation
odsapplication/vnd.oasis.opendocument.spreadsheet
odtapplication/vnd.oasis.opendocument.text
oggapplication/ogg
ogmapplication/ogg
pbmimage/x-portable-bitmap
pdbchemical/x-pdb
pdfapplication/pdf
pgmimage/x-portable-graymap
pgnapplication/x-chess-pgn
pgpapplication/pgp
pikchrtext/x-pikchr
plapplication/x-perl
pmapplication/x-perl
pngimage/png
pnmimage/x-portable-anymap
potapplication/mspowerpoint
potxapplication/vnd.openxmlformats-officedocument.presentationml.template
ppmimage/x-portable-pixmap
ppsapplication/mspowerpoint
ppsxapplication/vnd.openxmlformats-officedocument.presentationml.slideshow
pptapplication/mspowerpoint
pptxapplication/vnd.openxmlformats-officedocument.presentationml.presentation
ppzapplication/mspowerpoint
preapplication/x-freelance
prtapplication/pro_eng
psapplication/postscript
qtvideo/quicktime
raaudio/x-realaudio
ramaudio/x-pn-realaudio
rarapplication/x-rar-compressed
rasimage/cmu-raster
rgbimage/x-rgb
rmaudio/x-pn-realaudio
roffapplication/x-troff
rpmaudio/x-pn-realaudio-plugin
rtftext/rtf
rtxtext/richtext
scmapplication/x-lotusscreencam
setapplication/set
sgmtext/sgml
sgmltext/sgml
shapplication/x-sh
sharapplication/x-shar
silomodel/mesh
sitapplication/x-stuffit
skdapplication/x-koan
skmapplication/x-koan
skpapplication/x-koan
sktapplication/x-koan
smiapplication/smil
smilapplication/smil
sndaudio/basic
solapplication/solids
splapplication/x-futuresplash
srcapplication/x-wais-source
stepapplication/STEP
stlapplication/SLA
stpapplication/STEP
sv4cpioapplication/x-sv4cpio
sv4crcapplication/x-sv4crc
svgimage/svg+xml
swfapplication/x-shockwave-flash
tapplication/x-troff
tarapplication/x-tar
tclapplication/x-tcl
texapplication/x-tex
texiapplication/x-texinfo
texinfoapplication/x-texinfo
tgzapplication/x-tar-gz
th1application/x-th1
tifimage/tiff
tiffimage/tiff
trapplication/x-troff
tsiaudio/TSP-audio
tspapplication/dsptype
tsvtext/tab-separated-values
txttext/plain
unvapplication/i-deas
ustarapplication/x-ustar
vbtext/plain
vcdapplication/x-cdlink
vdaapplication/vda
vivvideo/vnd.vivo
vivovideo/vnd.vivo
vrmlmodel/vrml
wasmapplication/wasm
wavaudio/x-wav
waxaudio/x-ms-wax
webpimage/webp
wikitext/x-fossil-wiki
wmaaudio/x-ms-wma
wmvvideo/x-ms-wmv
wmxvideo/x-ms-wmx
wrlmodel/vrml
wvxvideo/x-ms-wvx
xbmimage/x-xbitmap
xlcapplication/vnd.ms-excel
xllapplication/vnd.ms-excel
xlmapplication/vnd.ms-excel
xlsapplication/vnd.ms-excel
xlsxapplication/vnd.openxmlformats-officedocument.spreadsheetml.sheet
xlwapplication/vnd.ms-excel
xmltext/xml
xpmimage/x-xpixmap
xwdimage/x-xwindowdump
xyzchemical/x-pdb
zipapplication/zip