appkiro.com

プレースホルダー画像生成

Images & Assets

任意のサイズ・背景色・文字色・ラベルでプレースホルダー画像を生成し、モックアップ・ワイヤーフレーム・開発に活用できます。

Width

Height

Background

Text

Custom Text (optional)

Preview

Placeholder Generator creates simple filler images at any size you need. Set the dimensions, pick colors, add optional label text, and download a PNG or SVG — all in the browser, with no account or upload required.

What it is

A placeholder image is a blank, labeled graphic used to hold space in a layout before real content is ready. This tool generates them on demand: you define the width, height, background color, text color, and an optional label, then export as a raster PNG or a scalable SVG. The preview updates live as you change any setting.

What it is useful for

Filling image slots in wireframes and mockups so the layout reads correctly before photography or design assets are ready.
Prototyping UI components — cards, hero sections, avatars, banners — with realistic proportions.
Providing developers with correctly sized stand-in images during front-end development so they can test responsive behavior without waiting for final assets.
Creating labeled test images for automated visual regression tests or screenshot comparisons.
Generating quick reference images for presentations and documentation where exact content does not matter yet.

When to use it

Reach for this tool any time you need an image of a specific size but the real asset is not available yet. Common moments include early-stage wireframing, handing off a component to a developer before the design is finalized, building a demo or prototype for a client review, or writing documentation that needs visual examples without using real user data.

How to use it

Enter a Width and Height in pixels, or click one of the preset buttons — HD (1920×1080), Square (1000×1000), Banner (1200×400), Thumbnail (300×200), Social (1200×630), or Avatar (400×400).
Choose a Background color using the color picker or by typing a hex value directly.
Choose a Text color the same way. The default combination of light gray background and medium gray text is intentionally neutral so placeholders do not distract from the surrounding layout.
Optionally type a Custom Text label. If you leave this empty, the tool displays the dimensions (e.g. 800 × 600) automatically.
Select PNG or SVG as the output format.
Click Download to save the file, or Copy Data URL to copy a base64-encoded data URI you can paste directly into HTML or CSS.

PNG vs SVG

PNG — a raster image at the exact pixel dimensions you set. Use it when you need a fixed-size file that behaves like a regular image everywhere.
SVG — a vector file that scales to any size without losing sharpness. Use it in web projects where the placeholder needs to be responsive, or when you want a tiny file size regardless of dimensions.

Tips

Use the Data URL option to embed the image directly in an <img src="..."> tag or a CSS background-image without needing a separate file.
For responsive mockups, SVG is the better choice — it renders crisply at any display size or resolution.
Color-code placeholders by type (e.g. blue for hero images, green for avatars) to make wireframes easier to read at a glance.
Add a short label like Product photo or Team headshot so collaborators know what the slot is for.

Frequently asked questions

Is there a maximum image size?

The width and height inputs accept values up to 4096px. Very large PNG files may take a moment to generate since the canvas has to fill every pixel in the browser.

What does Copy Data URL do?

It copies a base64-encoded version of the image as a data URI — a self-contained string that starts with data:image/png;base64,... or data:image/svg+xml;base64,.... You can paste it directly as an image source in HTML, CSS, or design tools that accept data URIs, without needing to host the file anywhere.

Can I use a custom font or add more styling?

The tool uses a monospace font and centers the text automatically. For more complex placeholder designs — custom fonts, borders, icons — an SVG editor or a design tool would give you more control.

Why does the preview look smaller than the actual dimensions?

The preview is scaled down to fit the panel. The downloaded file is always at the exact pixel dimensions you entered — the preview is just a visual reference.

Can I use these images in production?

Technically yes, but placeholder images are meant to be temporary. They carry no licensing restrictions since they are generated entirely in your browser, but they are not a substitute for real content in a finished product.

Does the tool store or upload my images?

No. Everything is generated locally using the browser Canvas API. Nothing is sent to any server.