Which image tool do you need?

Image ResizervsImage Compressor

One changes dimensions, the other changes bytes. The resizer is where you say "make this 800 pixels wide"; the file size is then whatever it happens to be. The compressor leaves the picture at its original dimensions and re-encodes it at a lower quality, so the same image simply costs less to download.

The part people get wrong: shrinking dimensions is a weak way to shrink a file. Halving the width and height cuts the pixel count to a quarter, but the file rarely drops to a quarter — how well the format compresses that particular picture matters more than how many pixels it has. If the goal is a number in kilobytes, compress. Two honest caveats: PNG is lossless, so a quality setting does nothing to it and the compressor can only reduce a PNG by scaling it down — switch the output to WebP or JPG for real compression. And in target-size mode, the tool lowers quality first and only starts reducing dimensions if quality alone cannot reach the size you asked for.

Image ResizervsInstagram Resizer

Use the plain resizer when you already know the number: an exact width and height, or a percentage of the original. It keeps the aspect ratio and nothing is cut off.

Use the Instagram one when you know the slot but not the number — a feed post, a 4:5 portrait, a story, a reel, a profile picture. It already holds those frame sizes, and because your photo will almost never match the frame's shape, it has to decide what happens to the difference: fill the frame and crop the overflow, fit the whole image inside and pad the edges, or stretch it. You pick, and you see the result before you download.

Image ResizervsPixel Art Upscaler

Both make an image bigger, by opposite methods. The resizer interpolates: it invents in-between colors so the result looks smooth, which is what you want for a photo. The upscaler replicates: every source pixel becomes a solid square block, at whole-number factors, so no color is invented and no edge softens.

Pick the wrong one and the damage is obvious. Interpolating a 32×32 sprite to four times its size blurs every hard edge into a smear — the thing that made it pixel art is gone. Going the other way is less destructive but still wrong: block-replicating a photograph gives you visible squares. Sprites, tilesets and icons drawn pixel by pixel go to the upscaler. Photographs and smooth illustrations go to the resizer.

Image CompressorvsImage Converter

The compressor keeps the container and lowers the quality inside it: a JPG goes in, a smaller JPG comes out. The converter changes the container itself: PNG to WebP, WebP to JPG, JPG to PNG.

Convert when something else demands a particular format, or when the format is the problem — a photo saved as PNG is large because PNG is lossless, and moving it to WebP or JPG helps far more than any quality slider will. Converting to JPG also throws away transparency, which is why the converter asks for a background color to flatten it onto. The converter handles batches; the compressor works on one file and reports the before and after size.

Sprite Sheet SlicervsInstagram Grid Splitter

Both cut one image into several. The Sprite Sheet Slicer is the general one: any number of rows and columns, grid lines you can drag individually when the content is not evenly spaced, and a Magic mode that reads the transparent gaps in a sprite sheet to find the frames wherever they sit.

The Instagram splitter does one job instead: an even 3×3, 3×2 or 3×1 of square tiles for a profile grid. It gives you a crop frame first, because a profile grid only looks right if the tiles are square, and it names the exported files in the order you need to post them — last tile first — so the finished grid reads correctly. Sprite frames go to the slicer; a photo going on a profile goes to the splitter.

PDF to ImagevsImage to PDF

Direction, and people do land on the wrong one. PDF to Image takes a PDF apart: each page is rendered to a PNG or JPG, at 72, 150 or 300 DPI, for all pages or a range like 1-3, 7. Image to PDF goes the other way: a set of JPG, PNG or WebP files becomes one PDF, in the page order you choose, sized to the image itself or to A4 or US Letter.