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Image · Resize

Scale images. Pixel‑perfect.

Set exact dimensions, lock the ratio, pick Lanczos3 or Mitchell. Watch a real-time before/after — then download. No upload, no account, no blur.

  • Lanczos3 resampling preserves edges sharper than any bicubic tool.
  • Aspect-ratio lock on by default — enter one side, the other follows.
  • Batch up to 50 images. Runs locally — zero bytes leave your device.
Input →
JPEG PNG WebP AVIF HEIC TIFF
→ Output: same or WebP / PNG

Used by 900K people · 6M images resized every month

Zero files uploaded · Runs on your CPU in a Web Worker · No account, no watermark, no nonsense.

900K
Monthly users
47%
Avg. scale
0
Files uploaded
What people say

Trusted by people who want precise pixels.

★★★★★

I've tried five different online resizers. This is the only one that doesn't turn my product photos into soft blurs. Lanczos3 is a real difference.

MR
Marcus R.
★★★★★

Batch resized 80 photos for a client deck in under 3 minutes. Aspect ratio locked perfectly the entire time. Nothing uploaded anywhere.

SL
Sarah L.
★★★★★

The before/after preview is so useful. I can compare at a glance whether the output still holds detail. No other free tool does this client-side.

AT
Andrea T.
★★★★★

Cover / Contain / Fill modes saved my workflow for creating social thumbnails. Exactly what I needed and it stays in the browser.

JK
Julia K.
★★★★★

I process screenshots for documentation every week. This tool respects retina ratios, gives me exact pixel control, and runs offline. Perfect.

DN
David N.
★★★★★

I resize documentation screenshots every week. The exact pixel control and ZIP export save me a lot of time compared to doing it manually.

FC
Frances C.
★★★★★

Switched from Photoshop "Export As" for quick resizes. Lanczos3 output is indistinguishable and I save minutes every day. Bookmarked forever.

TP
Thomas P.
★★★★★

Resized my entire portfolio to 1920px wide in one batch. All still look crisp at retina. The ZIP download is a thoughtful touch.

HV
Helen V.
★★★★★

I've tried five different online resizers. This is the only one that doesn't turn my product photos into soft blurs. Lanczos3 is a real difference.

MR
Marcus R.
★★★★★

Batch resized 80 photos for a client deck in under 3 minutes. Aspect ratio locked perfectly the entire time. Nothing uploaded anywhere.

SL
Sarah L.
★★★★★

The before/after preview is so useful. I can compare at a glance whether the output still holds detail. No other free tool does this client-side.

AT
Andrea T.
★★★★★

Cover / Contain / Fill modes saved my workflow for creating social thumbnails. Exactly what I needed and it stays in the browser.

JK
Julia K.
★★★★★

I process screenshots for documentation every week. This tool respects retina ratios, gives me exact pixel control, and runs offline. Perfect.

DN
David N.
★★★★★

I resize documentation screenshots every week. The exact pixel control and ZIP export save me a lot of time compared to doing it manually.

FC
Frances C.
★★★★★

Switched from Photoshop "Export As" for quick resizes. Lanczos3 output is indistinguishable and I save minutes every day. Bookmarked forever.

TP
Thomas P.
★★★★★

Resized my entire portfolio to 1920px wide in one batch. All still look crisp at retina. The ZIP download is a thoughtful touch.

HV
Helen V.
Anatomy · 01

The kernel decides how sharp your pixels land.

Every resampling algorithm is a mathematical kernel — a weighted average of neighboring pixels. The choice changes everything: blocky staircases, soft halos, or clean edges. We default to Lanczos3 because it is the gold standard for downscaling photos.

  • NN
    Nearest Neighbor
    Fastest and ugliest. Each output pixel copies its closest input neighbor — diagonal edges become pixelated staircases. Useful only for pixel art.
  • BILIN
    Bilinear interpolation
    Smooth but blurry. Weights the four surrounding pixels linearly. Better than nearest, but softens fine detail at scale.
  • LZ3
    Lanczos3 (default)
    Windowed sinc kernel over 3 lobes. Preserves edges, text and fine texture sharper than any bicubic — at minimal computational cost in WebAssembly.
Anatomy · 02

Fit mode is the decision the resizer makes when ratios don't match.

You want 1080×1080 from a 16:9 photo. The pixels don't divide cleanly. Three different answers exist — and the right one depends entirely on what the image is for.

  • cover
    Cover — fills the frame, crops edges
    Perfect for social thumbnails and hero images. The subject stays centered; excess pixels are cut. No letterboxing, no distortion.
  • contain
    Contain — fits entirely inside, adds padding
    Product photography and documents. The full image is always visible; transparent or solid bars fill the gaps.
  • fill
    Fill — stretches to exact dimensions
    Use intentionally for abstract textures or when distortion is acceptable. Always delivers the exact pixel count you asked for.
How it works

Three steps. Exact dimensions.

Drop your file, enter a target size, take the pixels home. Everything runs in a Web Worker on your device — never our server.

01 / DROP

Drag the image onto the folder.

JPEG, PNG, WebP, AVIF or HEIC. Up to 50 at a time. Or pick from Finder, Photos, anywhere on your device.

02 / SCALE

Set the target dimensions.

Enter width, height, or a percentage. The chain keeps your ratio locked. Hover to watch a 4K photo resize to 1080p in real time.

Width
4096 1920 px
Height
2731 1080 px
Scale 100% 47%
4096 × 2731 px ✓ 1920 × 1080 · WebP
03 / KEEP

Download. Or batch-zip the lot.

One click. EXIF stripped by default. Single file or ZIP for batches — never an email, never a watermark, never an account.

colosseo_1920.webp 1920 × 1080 Lanczos3 · WebP
The honest comparison

kindatool vs. the ones that need a server.

Not because the others are bad — because they don't have to be your default.

Feature comparison
★ Best pick kindatool
Preview (macOS)
Photoshop
ResizeImage.net
Runs entirely in your browser
Yes
Local app
Local app
Server
No account, no email
Never
N/A
Required
No login
Lanczos3 resampling
Default
Lanczos2
Yes
Bilinear only
Batch processing
Up to 50 / batch
One at a time
Actions / scripts
3 files (free)
Cover / Contain / Fill modes
All 3
Canvas size
Price
Free, forever
Free (macOS only)
$10.99–$69.99/mo
Free
Things people ask

Common questions about resizing.

Does kindatool upload my images to resize them?
No. Resizing runs entirely in your browser using the HTML Canvas API and a WebAssembly resampling kernel. Open DevTools → Network and you will see zero outbound requests during a resize. Your images stay on your device from start to finish.
What is Lanczos3 and why is it the default?
Lanczos3 is a windowed sinc interpolation kernel that samples a 6×6 neighborhood of pixels (3 lobes on each side) and weights them with a sinc function. It produces sharper edges than bilinear or bicubic resampling at similar speeds. It is the default in most professional image tools — Lightroom, GIMP, FFmpeg — and now available in your browser at zero cost.
How does the aspect-ratio lock work?
When the lock is on (default), entering a width automatically recalculates the height to preserve the original aspect ratio, and vice versa. You can also enter a scale percentage and both dimensions update together. Unlock it when you intentionally want to distort the image — for example, fitting a 16:9 photo into a 1:1 frame using Fill mode.
What is the difference between Cover, Contain, and Fill?
Cover scales the image so it fills the target frame entirely, then crops the overflow — the image is never distorted, but some pixels are cut. Contain scales it to fit inside the frame with no cropping, adding transparent or solid padding on the shorter axis. Fill stretches width and height independently to exactly match the target — distortion is intentional.
Can I resize a batch of images at once?
Yes. Drop up to 50 images at once. They are processed in parallel across available CPU cores inside a Web Worker pool. When all are done, click Download ZIP to get all resized files in a single archive. No watermark, no per-file limit.
Will resizing strip my EXIF metadata?
By default we strip EXIF, GPS and thumbnail metadata for privacy. From the advanced panel you can keep camera orientation, ICC colour profile, or the full EXIF block. The canvas resize itself does not require metadata, so the choice is entirely yours.
Pair it with

More image tools.

Compress
SSIM-aware encoder, up to −90%.
Open →
Convert
HEIC, AVIF, WebP, PNG, JPEG.
Open →
Crop
Free-form, ratio-locked, circle.
Open →
Watermark
Text or logo, batch overlay.
Open →
Blur
Gaussian, motion, faces.
Open →

Drop your images. Get exact pixels back.

Or paste a URL — we will fetch it client-side and run the same Lanczos3 pipeline. Nothing routes through our servers.

No upload No account No watermark Lanczos3