These are the Diablo IV Side Quests found in the Estuar continent. Side Quests are identified in the map and the minimap as a blue exclamation mark. However, there are side quests that start from an item that drops from mobs, corpses, mine nodes, and treasure chests in the open world (outdoors) or within dungeons. This list contains YouTube videos I uploaded for each Side Quest.

A Cold Faith (Item)Dobrev TaigaSoutheast Foothills
Better Days (Item)Dobrev TaigaKrol Forest
Bound by BloodDobrev TaigaMargrave
Call of the AncientsSeat of the HeavensBear Tribe Refuge
Chain of Possession (Lv 5+)Sarkova PassMenestad
Cries of InnocenceFrigid ExpanseEastern Plain
Depths of DespairDesolate HighlandsKyovashad
Exorcist's Cache (Item)Frigid ExpanseThe Deep White
Faith in BloodDesolate Highlands
Gold Well Spent (Lv 5+)Sarkova PassMenestad
Gory DisplayFrigid ExpanseOlyam Tundra
Hammer of the Champion (Lv 15+)
Legacies of Light's WatchDobrev TaigaMargrave
Legacy Unmade (Lv 5+)Sarkova PassMenestad
Malady of the Soul
Desolate HighlandsKyovashad
Menestad CoffersDesolate HighlandsKyovashad
Ravenous DeadGale ValleyYelesna
Secret of the SpringFrigid ExpanseOlyam Tundra
Shattered Tribute
Seat of the HeavensBear Tribe Refuge
Sight to MadnessDesolate HighlandsKyovashad
The Beast's ChallengeSeat of the HeavensBear Tribe Refuge
The Cleansing FlameDobrev Taiga
The Sealed DoorDesolate HighlandsKyovashad
The Dread MartyrFrigid ExpanseOlyam Tundra
The Woodsman of Nevesk
Desolate HighlandsNevesk
Traveler's PrayerGale ValleyYelesna
Unwritten EndDobrev TaigaKrol Forest
Unyielding Flesh (Lv 7+)Gale ValleyYelesna
A Price to Pay(Part of "The Heretic" Questline)
At Any Cost(Part of "To Walk a Dark Path" Questline)
Bad Blood(Part of "The Heretic" Questline)
By Three They Come(Part of "To Walk a Dark Path" Questline)
Coiled Grasp (Leads to Vyeresz Stronghold)Umir PlateauZarbinzet
Glittering Abundance (Starts from Gem-ladden Geode)Umir Plateau(All Ore Nodes in Umir Plateau)
Necrotic Research(Part of "The Heretic" Questline)
Poisoned Hearts(Part of "The Heretic" Questline)
Remnants of Faith Johanna QuestUmir PlateauZarbinzet
The Heretic
Umir PlateauZarbinzet
To Walk a Dark Path
Umir PlateauZarbinzet
Turbulent Waters(Part of "To Walk a Dark Path" Questline)
RemnantsCaldeumPrison of Caldeum (Dungeon)
Left in AshesTur Dulra (Stronghold)Tur Dulra
The Diviner
Tur Dulra (Stronghold)Tur Dulra
Tending NatureTur Dulra (Stronghold)Tur Dulra