Placeholder Image Generator
Generate a downloadable placeholder image at any size, colour and format.
Overview
The Placeholder Image Generator produces a downloadable PNG, JPEG, WebP or SVG of any size, colour and label, no external service required. Set the width, height, background colour and optional caption, choose a format, and the tool emits a binary file you can drop straight into a mockup, an empty CMS field or a unit-test fixture.
The generator is aimed at designers blocking out layouts, frontend developers needing offline placeholders without an external CDN call and content editors waiting on photography. Long-tail searches like "offline placeholder image generator", "custom size dummy image png" and "self-hosted placeholder service alternative" all resolve here.
How it works
For raster formats the tool draws on a server-side image surface (ImageSharp on .NET), fills the rectangle with the chosen background, measures the caption against a built-in sans-serif font and centres it. The result is encoded with the appropriate codec — image/png for lossless, image/jpeg with quality control, image/webp for smaller payloads. For SVG, the tool emits a one-element <svg> with an inline <rect> and centred <text>, which is the smallest possible output and renders crisply at any zoom.
Contrast for the caption is computed from the luminance of the background using the standard sRGB-to-luminance formula; if the background is light, the caption switches to dark text and vice versa. Dimensions are clamped to a sensible upper bound to prevent runaway allocations, and the request never leaves the server, so there is no external service to depend on.
Examples
800 x 600 PNG, slate background → 800x600.png ready for download
1200 x 630 social-card SVG → og-placeholder.svg
512 x 512 JPEG with caption "Cover art" → cover.jpg
2000 x 200 banner WebP → small payload, sharp at retina sizes
FAQ
Is there a maximum size?
The tool caps dimensions at a few thousand pixels per side to keep responses snappy and prevent abuse. SVG output is unbounded because it is vector.
Why does the caption switch colour?
The tool computes the background luminance and picks black or white text whichever offers better WCAG contrast, so the caption is always legible.
Can I omit the caption?
Yes. Leave the label blank and you get a clean colour swatch with no text.
Which format should I pick?
PNG for lossless mockups, JPEG for small file sizes when artefacts are acceptable, WebP for the smallest modern raster payloads, SVG for resolution-independent scaling.
Is the output safe to commit to source control?
Yes — the images are generated locally and contain no embedded metadata or external references.