Setting up a placeholder
Enter a width and height from 1 to 4000 pixels. The label defaults to the size, such as 1200 × 630, or you can type your own text of up to 60 characters, like Hero image or Product photo. Choose a background and text color from the swatches. The label is centered and scaled to fit, so it stays readable on a tall banner or a small thumbnail.
Nothing is uploaded: the image is drawn on the server from these settings, and the preview updates a moment after each change. Download PNG saves it with the size in the file name.
Embedding a placeholder by URL
The Use it directly box gives you an img tag with a full URL plus width and height attributes. The URL takes simple parameters: w and h for the size, bg and fg for the background and text colors as hex without the hash, and text for a custom label. Through the URL you can use any hex color, not just the swatches, and add format=jpeg or format=webp to change the file type.
Generated images are sent with long-lived cache headers, so a page that uses the same placeholder many times only downloads it once.
Why designers and developers use placeholders
Placeholders let you build and review a layout before final images exist, in wireframes, prototypes, CMS templates and email designs. With the width and height attributes set, they reserve the correct space so the page doesn't jump when the real image arrives. They are also handy for testing how responsive crops and object-fit settings behave at different shapes. Swap them for real images before launch.