Blood codes are classes that can be equipped to a player's character to alter their playstyle. Each blood code represents a different character in the world of Code Vein. Blood codes change the stats of the player's character, as well as give them access to unique abilities, both passive and active.

There are three different aspects of a Blood code:

• Blood code core
  • The base of the class. Obtaining one results in the character unlocking that class.
  • Blood code cores are awarded to the player while progressing through the game, given to the character by other NPCs after interacting with them, and found hidden throughout the game.
• Blood code vestige
  • Blood code powerups. Allows the player's character to unlock new abilities within that blood code. Some of these abilities, after being used enough, can even be used while the player's character has another blood code equipped!
• Blood code vestige parts
  • The components that make up a blood code vestige. When brought to Io, vestige parts can be used to gain access to memories from the characters that the blood code represents.
  • Blood code vestige parts are found scattered throughout the game. Some are very well hidden, so keep a close eye out for them!