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Marvin's Toolbox.

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Image Cropper & Resizer

Crop any image with rule of thirds, golden ratio and golden spiral overlays, snap to preset aspect ratios or set your own, then resize the result to exact pixel dimensions and export it as PNG or JPEG.

Everything runs locally in your browser. Your data never leaves your device.

Image

Drop an image here

PNG, JPG, WebP… Click to choose a file, or press Ctrl+V to paste one.

It never leaves your browser.

Next steps

Send this tool's output straight into another tool.

JPG Image Compressor

Shrink any image with as little quality loss as possible. Pick a WhatsApp, Instagram or Discord preset, or switch to Custom to hit a hard file size or a fixed quality, downscale with aspect-locked resolution sliders, and keep or strip EXIF metadata. Live preview, multiple images at once.

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Image Converter

Convert images between JPEG, PNG, WebP and AVIF. Drop in as many as you like, pick a format, and dial in the quality for the lossy ones. When you convert to JPEG, choose the colour that fills any transparency. Live previews, download one or all at once.

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EXIF Editor

See and edit the EXIF metadata inside a photo, then download it with your changes or save a copy with all metadata removed, GPS included. It reads JPEG, PNG, HEIC and more, and edits JPEG files.

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EXIF Transfer

Copy the EXIF metadata from one photo onto another without changing the destination's pixels. That covers camera model, lens, focal length, exposure, GPS and more. Choose to replace all metadata or only fill in what the source provides.

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Image Annotator

Draw arrows, boxes, text, highlights and numbered steps on a screenshot, blur or pixelate anything private, crop the result and add a watermark. Undo works as you expect, and the finished image downloads as PNG or JPG or goes straight to your clipboard.

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Hash Generator

Hash text or a file with MD5, SHA-1, SHA-256, SHA-512, SHA-3, BLAKE2, BLAKE3, CRC32 and more, all computed live as you type. Compare against an expected checksum and copy any digest.

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Checksum Validator

Verify a checksum online: drop a file, paste the expected checksum and see instantly whether they match. The hash type is detected from the checksum itself, covering MD5, SHA-1, SHA-256, SHA-512, BLAKE3, CRC-32 and more, and sha256sum lines or whole checksum files can be pasted as-is.

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Data Compressor

Compress text or a file with gzip, deflate, brotli or Zstandard and see the size before and after, the compression ratio and how long it took. One click tries every method and recommends the smallest result.

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Data Decompressor

Decompress gzip, deflate, brotli or Zstandard data from a file or pasted Base64 and read the result as text or download it. Detects the format from the magic bytes where possible, with a manual override.

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About the Image Cropper & Resizer

This tool cuts an image down to exactly the frame you want. Drop in a photo or screenshot, drag the crop handles, and watch composition guides like the rule of thirds or the golden spiral help you place the subject well.

The crop can run free, snap to a preset aspect ratio like 1:1, 16:9 or 9:16, or follow a ratio you type yourself. Before cropping you can rotate the image in 90 degree steps and flip it, and after cropping you can scale the result to exact pixel dimensions and save it as PNG or JPEG.

What you can do

  • Crop an image to a preset aspect ratio like 1:1, 4:3, 3:2, 16:9, 9:16, 21:9 or 4:5, or type a custom ratio.
  • Compose the crop with rule of thirds, golden ratio, golden spiral, diagonal or center guides.
  • Set the crop rectangle to exact pixel values for position and size.
  • Rotate a photo in 90 degree steps or flip it before cropping.
  • Resize the cropped result to exact pixel dimensions, with the aspect ratio locked or free.
  • Export the crop as PNG, or as JPEG with a quality slider.

How to use the Image Cropper & Resizer

  1. 1Drop an image, click to choose one, or paste it with Ctrl+V.
  2. 2Rotate or flip the image if it needs straightening first.
  3. 3Pick an aspect ratio, or stay on Free and drag any shape you like.
  4. 4Adjust the crop with the handles, the arrow keys, or the exact pixel inputs, using a composition guide if it helps.
  5. 5Set the output size, keep it locked to the crop's proportions or unlock it, and pick PNG or JPEG.
  6. 6Download the result or copy it to the clipboard.

Composition guides

The guides draw inside the crop selection and move with it. The rule of thirds splits the frame into nine equal parts, and placing the subject on a line or an intersection usually reads better than centering it. The golden ratio grid does the same with the lines pulled closer to the middle, at about 38 and 62 percent. The golden spiral suggests a path for the eye toward its smallest winding, and you can rotate it in quarter turns or mirror it so it matches your subject. Diagonal and center guides round the set out for symmetric or dynamic framings.

Resizing and formats

The output size starts at the crop's own pixel size, and the quick percent chips scale it in one click. Shrinking an image keeps it sharp. Enlarging it beyond the crop cannot invent detail, so the tool warns you when the output would be upscaled. PNG keeps transparency and every pixel exact. JPEG is smaller for photos but has no transparency, so see-through areas turn white.

If the file needs to hit a size limit before you share it, send the result to the JPG Image Compressor. For formats beyond PNG and JPEG, the Image Converter takes it from here.

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Color Blindness Simulator

See any image the way people with a color vision deficiency see it. Upload a picture and preview protanopia, deuteranopia, tritanopia, the milder anomalous forms and monochromacy next to the original, then download any simulation as a full resolution PNG.

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Color Palette Extractor

Pull the dominant colors out of any image as a ready-to-copy palette. Choose how many colors you want, copy each one as HEX, RGB or HSL, and export the whole palette at once.

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EXIF Editor

See and edit the EXIF metadata inside a photo, then download it with your changes or save a copy with all metadata removed, GPS included. It reads JPEG, PNG, HEIC and more, and edits JPEG files.

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EXIF Transfer

Copy the EXIF metadata from one photo onto another without changing the destination's pixels. That covers camera model, lens, focal length, exposure, GPS and more. Choose to replace all metadata or only fill in what the source provides.

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Favicon Generator

Turn any image into a complete favicon set: a multi-size favicon.ico, PNG icons in every common size, Apple touch and Android icons, a web manifest and the HTML tags to paste into your page. Download everything as a zip.

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