Colour pallets:
Coolors: https://coolors.co/
Color Hunt: https://colorhunt.co/
Color Hex: https://www.color-hex.com/
Pallet List - Lospec: https://lospec.com/palette-list
Audio:
SoundBible.com: http://soundbible.com/
freesound: https://freesound.org/
Youtube Audio Library: https://www.youtube.com/audiolibrary/music?nv=1
Assets:
OpenGameArt.org: https://opengameart.org/
Kenney: https://kenney.nl/assets
Assets - itch.io: https://itch.io/game-assets
3D Models:
TurboSquid: https://www.turbosquid.com/
Poly: https://poly.google.com/
Textures:
Texture Haven: https://texturehaven.com/
Fonts:
DaFont: https://www.dafont.com/
Google fonts: https://fonts.google.com/
Font Squirrel: https://www.fontsquirrel.com/
Images:
Pixabay: https://pixabay.com/
Unsplash: https://unsplash.com/
Story Generator:
Seventh Sanctum: https://www.seventhsanctum.com/generate.php?Genname=storygen
Steampunk Random Story Generator: https://www.magatsu.net/generators/steampunk/index.php
Management:
Trello: https://trello.com/
Milanote: https://app.milanote.com/