Free Resource

Art

• OpenGameArt (2D + 3D)
• Unity Asset Store (2D + 3D + Sound)
• Kenney (2D + 3D)
• Game-Icons (2D)
• Textures.com (Textures)
• Poliigon (Textures)
• Poly.pizza (3D)
• Mixamo (Animations)
• Kaylousberg (3D)
• Craftpix (2D)

Fonts

• Fontsource (Fonts)
• Font Squirrel (Fonts)
• Google Fonts (Fonts)

Audio

• Incompetech - Royalty Free Music (Music)
• Free Music Archive (Music)
• Freesound (SFX)
• OpenGameArt (Music + SFX)
• Kenney (Music + SFX)
• Soniss (SFX)
• artlist
• mixkit 
• freesound
• pixabay

Tools

• BitFontMaker2 (Fonts)
• Photopea (Art)
• sfxr (SFX)
• Chiptone (SFX)
• Bosca Ceoil (Music)
• BeepBox (Music)
• Lospec (Palettes)
• Easy Releasy (itch.io page designer)

Tiny Tools (More!)