Systems and methods for blockchain-based tracking and selective access to user data

A user data tracking system comprising:

• one or more hardware processors configured to:
• generate a token for a particular user on a blockchain and a key for accessing the token on the blockchain;
• provide the key to a first network site and a second network site;
• enter a first set of user data by the first network site to the token based on said providing the key to the first network site, the first network site tracking activity of the particular user on the first network site, and the first network site issuing one or more messages to the blockchain that add the set of user data to the token without action from the particular user or messaging from a device of the particular user;
• and
• customize content that is presented to the particular user at the second network site based on one or more content from a plurality of content of the second network site having attributes that match the first set of user data entered by the first network site in the token, wherein customizing the content comprises the second network site retrieving the first set of user data from the token in response to providing the key to the second network site and the second network site matching the attributes of the one or more content to the first set of user data.

A non-transitory computer-readable medium, storing a plurality of processor-executable instructions to:

• generate a token for a particular user on a blockchain and a key for accessing the token on the blockchain;
• provide the key to a first network site and a second network site;
• enter a first set of user data by the first network site to the token based on said providing the key to the first network site, the first network site tracking activity of the particular user on the first network site, and the first network site issuing one or more messages to the blockchain that add the set of user data to the token without action from the particular user or messaging from a device of the particular user;
• and
• customize content that is presented to the particular user at the second network site based on one or more content from a plurality of content of the second network site having attributes that match the first set of user data entered by the first network site in the token, wherein customizing the content comprises the second network site retrieving the first set of user data from the token in response to providing the key to the second network site and the second network site matching the attributes of the one or more content to the first set of user data.