Blurhash
Library to show colorful blurry placeholders while your content loads
... to be added as a field in a JSON object and to be stored in a database. The implementations are small and easy to port to new languages, and the end result is a smooth and interesting experience for your users. In short, BlurHash takes an image and gives you a short string (only 20-30 characters!) that represents the placeholder for this image. You do this on the backend of your service and store the string along with the image.