Coinbase's responsive alerts

Coinbase is a platform where people can buy, sell and transfer digital money. Out of the thousands of cryptocurrencies that can be traded, Coinbase only supports three: Bitcoin, Litecoin and Ethereum. These three currencies are among the most popular and regarded as the most secure, which is something that Coinbase takes seriously. Moreover, with fewer options available, the complexity of using Coinbase is reduced, making it an easy entry point for newcomers to cryptocurrencies. 

The biggest problem Coinbase has in acquiring and retaining users is the risk associated with cryptocurrencies. Bitcoin, for example, is highly volatile and has experienced drops in value of up to $2.5k in a single day. Rapid change means users who've invested money via Coinbase need to react fast to changes in prices, which Coinbase supports with a price alert function. The function is customizable, so users can set price change alerts that are relevant to their goals. As a result, the user feels more comfortable with the risks associated with cryptocurrencies because they know they'll be notified and can react to changes that matter to them.

Why this is really good UX:

• The price alert function uses elements of a dial face with a pointer, scale marks and numbers at equal intervals. The familiarity of the dial face provides users with an affordance—strong cues on how to use it. As a result, users understand what to do just by looking at it.
• The layout of the alert function conforms to the mental model of how numbers ascend if written in order: the values on the right are higher than the left. Matching the interface to work in a way that people expect it to work—from their pre-existing knowledge—helps create a frictionless experience.
• To dispel ambiguity when using the function, the user's actions are instantly communicated through the state of the “above” and “below” text in relation to the current price. If the user moves the dial towards the right, the text “above” changes to a bold state. This helps the user take the appropriate action to set the right price.