Data Limit for Custom Contact Data
Previously, the amount of custom JSON data that could be stored alongside every contact was unlimited. It’s now possible to store up to 8 KB of custom data for every contact.
While 8 KB might not sound like a lot of data, it should be more than sufficient for almost any purpose. 8 KB are equivalent to a 1,000 word text document or a JSON document with 500 data points, depending on the structure of the data.
The newly introduced campaign data feature allows for twice as much data with 16 KB per campaign.