Font licences for the fonts bundled with Thumbnailr (all files in /fonts/ are subsets of these fonts).

SIL Open Font License 1.1
  Anton ............. Anton-OFL.txt
  Bangers ........... Bangers-OFL.txt
  Bebas Neue ........ BebasNeue-OFL.txt
  DM Sans ........... DMSans-OFL.txt         (site text)
  Inter ............. Inter-OFL.txt
  Montserrat ........ Montserrat-OFL.txt
  Poppins ........... Poppins-OFL.txt
  Russo One ......... RussoOne-OFL.txt
  Silkscreen ........ Silkscreen-OFL.txt     (site labels)
  Unbounded ......... Unbounded-OFL.txt      (site headings and the Thumbnailr wordmark, as outlines)

Apache License 2.0
  Luckiest Guy ...... LuckiestGuy-Apache-2.0.txt
  Permanent Marker .. PermanentMarker-Apache-2.0.txt

The fonts are unmodified apart from subsetting to Latin characters and conversion to WOFF2
(the same kind of subsets Google Fonts serves). Copyright notices are in each licence file.
Sources: https://github.com/google/fonts