Target by radius from ZIP code

[BenCirillo]

Only other thread I found on this topic was from 2015, so I thought it might be worth a repost:  

Is there a feature - or clever workaround - that lets you target by radius from a ZIP code? The email system we're migrating from had this as a feature. If I wanted to target the Chicago metropolitan area, I could set a filter for within 50 miles of 60613. That would pull in Chicago and all the suburbs (including Northwest Indiana), but not downstate. Is there a way to do something like this in Marketo that doesn't involve manually adding either every ZIP code or every city in the area I want to target? 

[SanfordWhiteman · Accepted solution]

Nothing built-in. You'd have to use a webhook to do this.

The Google Maps Platform API, for example, can see if 2 locations are in the same KML circle. And there may be other geo APIs that have this kind of query built-in and are webhook-compatible (i.e. can be called directly using Call Webhook as opposed to calling custom code that in turn calls the service).