resize_image

Resize an image locally using the sharp library. This tool does not require an API key and works entirely on your machine.

Arguments

Argument	Type	Required	Default	Description
image	string	Yes	—	Input image as a base64 string, data URI (data:image/png;base64,...), local file path, or URL.
width	number	No	—	Target width in pixels.
height	number	No	—	Target height in pixels.
scale	number	No	—	Scale factor, for example 0.5 for 50%.
fit	string	No	cover	How to fit the image when both width and height are provided.
output_path	string	No	—	If provided, saves the resized image to disk and returns the file path.
format	string	No	—	Output format: jpeg, png, webp, avif, gif. Defaults to the input format.
quality	number	No	—	Quality for lossy formats (1–100).

You must provide at least one of width, height, or scale.

Fit modes

• cover — Crop to fill both dimensions, preserving aspect ratio.
• contain — Fit within both dimensions, preserving aspect ratio; may add empty space.
• fill — Stretch to exactly match both dimensions.
• inside — Fit within the given dimensions; result may be smaller than requested.
• outside — Cover the given dimensions; result may be larger than requested.

Output behavior

• If output_path is omitted, the resized image is returned as a base64 string.
• If output_path is provided, the image is saved to that path and the path is returned.
• When only width or height is provided, the original aspect ratio is preserved.
• When format is omitted, the output format matches the input image format.

Examples

Scale by width from a data URI

{
  "image": "data:image/png;base64,iVBORw0KGgo...",
  "width": 800
}

Resize an image from a local file path

{
  "image": "/path/to/photo.jpg",
  "width": 800,
  "height": 600,
  "fit": "cover"
}

Resize an image from a URL

{
  "image": "https://example.com/photo.png",
  "scale": 0.5,
  "format": "webp",
  "quality": 85,
  "output_path": "/tmp/resized.webp"
}

Best practices

• Provide only width or height when you want to preserve the aspect ratio.
• Use fit: "cover" for thumbnails and fit: "contain" when you need the entire image visible.
• Set quality between 70 and 90 for a good balance of size and visual quality.