tool time

Quickly compress your PNGs (and use more 24-bit PNGs because of it!) https://tinypng.com/

Compress JPGs (although photoshop save for web with optimization options should be your first choice so you can visually see the image quality) https://tinyjpg.com/

dynamic placeholder images with a simple url syntax https://placeholder.com/

quickly find out if that tip, trick or technique works in every or any browser https://caniuse.com/