Here is the Google Inbox user interface created with Sketch app. Freebie released by Erika Ito.
The Android Lollipop UI kit created with Sketch app. It contains 45 useful elements. Created by Jerry Cao.
Android Lollipop UI kit
Tethr UI kit for iOS is now available for free! It’s got over 250 of the most common UI elements to make prototyping that much faster.
Tethr – Free UI kit for iOS
Teracy is a wireframe kit for Sketch app created to help speed up your wireframing process. Created and released by hoatle.
Teracy wireframe kit for Sketch
A set of 4 hand drawn sketch mockups. High quality photos and hand sketch generator. Released by Alex Byrne.
Free PSD hand drawn sketch mockups
A nice little set of vector-based health related icons for Adobe Illustrator CS and Sketch 3.1+. Freebie released by Creativedash.
25 health icons – AI + Sketch
More than 100 simple line icons and provided in many different formats (PSD, Sketch, SVG, PNG and ESP). Freebie created by Mirko Monti.
100+ simple line icons – PSD + Sketch + SVG
Jellycons is a free pack of pixel-perfect iOS8 app icons created with Apple Sketch by LoveUI.co.
Jellycons – 30 Sketch iOS8 icons
Silver iPhone 6 & 6 Plus mockups created with Sketch vector shapes. A freebie released by Hudson-Peralta.
iPhone 6 & 6 Plus mockups – Sketch
Here is a clean and minimal UI kit made with Sketch app. Freebie created and released by Mateusz Dembek.
Clean UI Kit for Sketch
Here is a set including 440 free icons, provided in both line and solid versions. They are all available in PSD, EPS and Sketch formats.