Can I blur just a part of an image?

Regional blur is available via the selection tool in the advanced panel. Draw a rectangle, set the radius, and only that area is affected.

Image · Blur

Blur in, blur out.
Not a pixel uploaded.

Drop a JPEG, PNG or WebP. Set the radius, pick the mode, download. Runs locally in your browser — no upload, no server.

Zero server requests — WebAssembly only
Gaussian, motion and radial modes
Batch up to 50 images at once

Blur an image See how it works

★★★★★ 4.8 / 5 · 9,284 reviews Zero uploads, always

blur.kindatool colosseo.jpg 2752 × 1536

Radius

14 px

Passes

3 ×

Sigma

4.0

Gaussian σ 4.0

Supports →

JPEG PNG WebP AVIF HEIC

→ Output: JPG · PNG · WebP

Trusted by 890K people · 3.1M images blurred every month

No upload endpoint. Processing runs locally — your images stay in the browser tab.

890K

Monthly users

Server requests

Blur modes

What people say

License plates, faces, client mockups.

★★★★★

I blur license plates, faces and emails in screenshots before sharing. Drag in, set the radius, download — no steps in between.

Marcus R.

★★★★★

Background blur on portrait batches. Drop a folder, set the radius, grab the ZIP. Much faster than doing it one by one in Photoshop.

Sophie B.

★★★★★

Blurring faces in social media posts used to mean uploading to some sketchy site. Now I just drag the file in and it's done. Private and instant.

Lucas M.

★★★★★

Batch background blur on 40 portraits — set the radius, drop the folder, download the ZIP. Done before the coffee was ready.

Anna T.

★★★★★

I use this to redact client screenshots before adding them to reports. The blur runs in the tab — nothing leaves the machine.

David N.

★★★★★

We redact sensitive document photos before publishing. This replaced our Photoshop workflow entirely — no installs, no subscription, no uploads.

Frances C.

★★★★★

The radial blur for hero section backgrounds is exactly what I needed. Clients love the depth-of-field effect and I can deliver it in under a minute.

Thomas P.

★★★★★

I blur faces, logos and text in mockups before sending over for review. Precise enough for tight crops and quick enough to not slow down the process.

Helen V.

★★★★★

I blur license plates, faces and emails in screenshots before sharing. Drag in, set the radius, download — no steps in between.

Marcus R.

★★★★★

Background blur on portrait batches. Drop a folder, set the radius, grab the ZIP. Much faster than doing it one by one in Photoshop.

Sophie B.

★★★★★

Blurring faces in social media posts used to mean uploading to some sketchy site. Now I just drag the file in and it's done. Private and instant.

Lucas M.

★★★★★

Batch background blur on 40 portraits — set the radius, drop the folder, download the ZIP. Done before the coffee was ready.

Anna T.

★★★★★

I use this to redact client screenshots before adding them to reports. The blur runs in the tab — nothing leaves the machine.

David N.

★★★★★

We redact sensitive document photos before publishing. This replaced our Photoshop workflow entirely — no installs, no subscription, no uploads.

Frances C.

★★★★★

The radial blur for hero section backgrounds is exactly what I needed. Clients love the depth-of-field effect and I can deliver it in under a minute.

Thomas P.

★★★★★

I blur faces, logos and text in mockups before sending over for review. Precise enough for tight crops and quick enough to not slow down the process.

Helen V.

Anatomy · 01

The kernel — and why the center matters most.

Gaussian blur works by convolving every pixel with a weighted kernel. The center pixel carries the highest weight; influence falls off with distance according to the Gaussian curve. That's what makes it look natural — gradual, not abrupt.

σ (sigma)
Standard deviation of the curve
Higher sigma = softer spread for the same radius. The default σ 1.4 mirrors how the human eye perceives blur falloff.
Radius
How far the kernel extends
A radius-12 kernel is 25×25 pixels wide. We pad the image edges to avoid hard borders — invisible to you, invisible to your audience.
Passes
3× separable passes for performance
A 2D Gaussian separates into two 1D passes. Three passes converge on the true result while running 6× faster than a naive 2D loop.

Privacy masking faces · plates · documents

privacy

Background bokeh portrait depth-of-field

artistic

UI & hero backgrounds frosted-glass · soft fills

design

Anatomy · 02

Not just artistic — deeply practical.

Blur protects. Blur focuses. Blur creates. The same algorithm underpins three entirely different intentions — and the right radius for each differs by an order of magnitude.

r 2–6
Subtle depth
A light touch on backgrounds draws the eye forward without erasing the scene. Portraits, product shots, e-commerce cards.
r 12–24
Clear redaction
License plates and faces need enough blur to be unrecognisable at 1× but not so much the image looks edited. r14 σ4 is the forensic-standard threshold.
r 40+
Full abstraction
Hero section backdrops, frosted overlays, noise reduction on flat color fields. The image becomes texture — beautiful texture.

Blur Modes

Four kinds of soft.

Different algorithms. Different intentions. Pick the one that matches the effect you're after — or let the preset suggest.

01 · Gaussian

The universal standard.

Weighted average across a bell-curve kernel. Even, natural, predictable — the default for portraits, backgrounds, and privacy masking. Every other mode is derived from this one.

02 · Motion

Directional. Intentional.

Averages pixels along a specific angle — 0° to 360°. Used for speed effects on cars or sport photos, and for simulating long-exposure light trails. Axis and distance are both adjustable.

03 · Radial

Soft from the outside in.

Intensity increases from center to edge. Perfect for depth-of-field simulation where you want a sharp subject and progressively blurred surroundings — without masking anything manually.

04 · Box

Flat kernel. Fast result.

Unweighted average over a rectangular region — every pixel in the kernel counts equally. Slightly harsher than Gaussian but runs faster on very large radii. Ideal for noise reduction and pixel art aesthetics.

How it works

Three steps. Zero uploads.

Drop the file, set the radius, take the result. The entire pipeline runs in a Web Worker on your machine — nothing routes through us.

01 / DROP

Drop the image onto the zone.

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

02 / SET

Set the radius. Watch the preview.

Slide the radius control and watch the result update live. Switch between Gaussian, motion, and radial modes from the same panel.

Blur radius12px

Gaussian · σ 3.2

03 / KEEP

Download. Batch-zip the lot.

One click. Single file or ZIP for batches. No email, no account, no watermark burned into your work.

colosseo-blurred.jpg
Gaussianr12 · 2752×1536

The honest comparison

kindatool vs. the ones that upload.

Because "free online blur" usually means your image goes somewhere first.

Feature comparison

★ Best pick kindatool

Photoshop

Canva

Fotor

Runs entirely in your browser

Yes

Desktop app

Server

No account, no email, no sign-up

Never

Adobe ID required

Required

Gaussian + Motion + Radial modes

All 4

All

Gaussian only

Partial

Batch processing

Up to 50 / batch

Actions (complex)

1 at a time (free)

No watermark

Never

Free plan

Price

Free, forever

$10.99–$69.99/mo

Free / $15/mo pro

Free / $8.99/mo pro

Things people ask

Common questions about blur.

Does kindatool upload my images to blur them?

No. Every pixel is processed locally in your browser using a WebAssembly build of the blur engine. Open DevTools → Network and you'll see zero outbound image requests. We literally don't have a server to send your file to.

What blur modes are available?

Gaussian (standard soft blur), Motion (directional, angle-adjustable), Radial (center-sharp falloff), and Box (flat-kernel, fast on large radii). All four are adjustable by radius and, for Gaussian, by sigma. Motion blur also exposes an angle control from 0° to 360°.

What's the difference between radius and sigma?

Radius sets how many pixels out the kernel extends — the physical size of the blur window. Sigma (σ) controls the standard deviation of the Gaussian curve within that window. A higher sigma with the same radius makes the blur softer at the edges and more concentrated at the center. A good starting point: σ ≈ radius / 3.

Can I blur just a specific region of an image?

Yes. Regional blur is available via the selection tool in the advanced panel — draw a rectangle over the area you want to affect, set the radius, and only that region is blurred. The rest of the image is left untouched. Particularly useful for privacy masking faces and plates.

Is there a maximum blur radius?

Up to 100px. Beyond that the result approaches a flat color and the extra computation isn't worth it. The tool warns you if the chosen radius exceeds 25% of the shorter image dimension — at that point you're blurring more pixels than exist to average from the edges.

How is this different from Photoshop or Canva Blur?

Photoshop is $20/month and requires a desktop install — it's the full standard, but overkill if you just want to blur an image. Canva uploads your files to their servers, runs the blur there, and is limited to Gaussian on the free tier. kindatool is local, batched, free, and exposes all four blur modes — no subscription, no upload, no install.

Pair it with