Show HN: Open-Sourcing InboxSDK (YC S11) – Build Apps in Gmail Hi HN! We’re Aleem, Chris, Borys, Meichen and Zach from Streak (YC S11) and today we’re open sourcing our InboxSDK https://ift.tt/2H5FlBq , which makes it easy to build apps for Gmail. Over 1.8B users spend their days in Gmail! Having your app built into the Gmail workflow is a better user experience and gives you great user retention. InboxSDK gives you a high-level, declarative API to insert your UI into Gmail without having to directly manipulate the DOM yourself. End users install a browser extension to use your app. The SDK can add UI to multiple areas of Gmail. For example, adding a button is as simple as: composeView.addButton({ title: "My Nifty Button!", iconUrl: 'https://ift.tt/InEHRut', onClick: function(event) { event.composeView.insertTextIntoBodyAtCursor('Hello World!'); }, }); InboxSDK enables you to add info to the sidebar on threads, add items in the left navigation tree, insert res...