Alttoalternative to
Convert a PDF Tools
Free · No sign-up · Runs in your browser

Resize an image.

This free image resize tool scales JPG and PNG images by percentage or exact pixel size for faster uploads and smaller attachments — batch process as many as you like, without a single file leaving your device.

Not uploaded — nobody sees it Percentage or exact pixels Keeps PNG transparency No subscription or account
Your files are never uploaded — they’re processed right here in this browser tab, on your device. There’s no server involved, so we never see them, copy them or keep them.
How it works

Three steps, no waiting on a server

Altto's resize tool works right in your browser tab using the canvas built into every modern browser, so there's no upload queue and no “processing your file” spinner tied to someone else's servers.

01

Add your images

Drop in one or more JPG or PNG files.

02

Choose percentage or exact size

Scale proportionally, or fit within (or force) a target pixel size.

03

Save your images

One downloads directly; several come back as a .zip.

Why this runs in your browser, not on a server

Photos often contain things you'd rather not hand to a stranger's server just to resize them. Altto skips that step completely — there's no server for it to go to.

  • Nothing is uploaded, everEvery image is decoded and resized using your browser’s own canvas, because there’s no server on the other end. That also means we can’t see it, copy it or keep it.
  • No account, no email wallResize as many images as you like without signing up or handing over an email address.
  • Batch resize built inAdd a whole folder of images at once and get them all back together.
0

images stored on our servers. There’s no server involved at all — each resized image is built once, then everything happens locally.

FAQ

Frequently asked questions

The practical details on what this tool can and can’t do. Need to shrink file size instead of dimensions? See Compress Image.

Will resizing distort my image?
Only if you choose to let it. With “Fit within this size” ticked, each image is scaled to fit inside your target box while keeping its own proportions, so it never looks stretched or squashed. Untick it and fill in both width and height to force that exact size instead, which can distort an image whose proportions don't match. There's also a “Don't enlarge” option (on by default) so a small image isn't blown up past its original size and made blurry.
What image formats are supported?
JPG and PNG. The output keeps the same format as your original, so a PNG's transparency is preserved rather than flattened.
Can I resize by percentage instead of exact pixels?
Yes — switch to Percentage mode and pick 25%, 50% or 75% of each image's original size. It's applied to every image individually, so a batch of different-sized images all scale down proportionally.
Can I resize several images at once?
Yes — add as many images as you like. One downloads directly; more than one comes back as a .zip.
Is my image uploaded anywhere?
No — nothing is ever uploaded. Every image is decoded and resized entirely inside this browser tab using the canvas built into your browser. There's no server involved at all, so there's nothing for Altto to see, copy or keep.
Do you keep a copy of my images?
No. There's no upload, so there's nothing on our side to keep. See the Privacy Policy for details.
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