Image tool
Image Compressor
Compress an image in your browser to shrink its file size for the web, email, or uploads. The tool re-encodes the image as a JPEG and shows you the before/after result so you can see exactly what you are getting.
Everything runs locally — your image never leaves your device.
Privacy & data handling
Browser processingThis tool processes your input locally in your browser. Nothing is uploaded to a server or sent to an external service.
Interactive tool
Image Compressor
Choose files to process
Images are re-encoded as JPEG to reduce size. PNG transparency and original format are not preserved.
Overview
What does Image Compressor do?
This compressor re-encodes your image as a JPEG at a fixed quality level. JPEG is a lossy format that drops fine detail the eye rarely notices, which is what makes files dramatically smaller.
The output is always a JPEG. If your original was a PNG with transparency, the transparency is not preserved — the transparent area becomes a solid (usually white or black) background in the JPEG. For transparent images, keep the PNG and use a different workflow.
The tool shows your original and the compressed result side by side, including both file sizes, so you can judge the quality/size trade-off before downloading.
Under the hood
How does it work?
Your image is decoded in the browser and drawn onto a canvas — an HTML element that gives the browser direct access to pixel data. The canvas is then encoded to a JPEG blob at a quality setting of 0.7 (70%), which balances visible quality against file size.
The before/after comparison is straightforward: the original file size is measured from the file you chose, and the compressed size is the byte length of the newly encoded JPEG. Both are displayed with the image preview.
Because everything runs in the browser with the HTML5 canvas API, there is no upload, no server, and no file size limit beyond what your device can handle in memory.
Key features
Features of Image Compressor
Use cases
When should you use Image Compressor?
Website images
Shrink photos before uploading so pages load faster without visibly degrading quality.
Email attachments
Bring a 5 MB photo down to under 1 MB so it actually fits in an email.
Marketplace and form uploads
Many platforms cap image sizes. Compress before you upload and avoid rejection.
Social media posts
Smaller images upload faster on mobile connections and use less data.
Step-by-step
How to use Image Compressor
- Step 1
Upload your image.
- Step 2
Adjust the quality slider to balance size and quality.
- Step 3
Download your compressed image.
Real example
Example
Before
product-photo.png 2000 × 1500 px 4.8 MB
After (JPEG, 70% quality)
product-photo.jpg 2000 × 1500 px 1.1 MB
Illustrative example. Real savings depend on the image content — a photo with smooth gradients compresses far more than a screenshot full of sharp text.
Technical information
How the details work
JPEG compression works by discarding high-frequency detail that human vision is bad at noticing, then compressing what remains. The quality setting controls how aggressively that happens: higher quality keeps more detail at a larger size; lower quality shrinks the file but can introduce artifacts like blocking and halos around edges.
The HTML5 canvas API performs the encoding in the browser using the device's native codec. This means results can vary slightly between browsers and devices — the same image at the same quality setting may produce a marginally different size on different systems.
Two practical notes: PNG files with transparency will lose the transparency when converted to JPEG, and extremely large images (tens of thousands of pixels) can exceed canvas limits in some browsers, in which case the tool will report that the image could not be processed.
Privacy & security
Your data stays yours
Your image is compressed entirely in your browser with the canvas API. It is never uploaded or stored.
Local processing — files stay in your browser
- The image is decoded and re-encoded locally — no copy is sent to any server.
- The compressed JPEG is generated on your device and downloaded directly.
- Nothing is retained after you close the tab.
- Analytics only record the page visit.
Limitations
What this tool does not do
- Output is always JPEG — PNG transparency is not preserved.
- The quality setting is fixed at 70% in the current version.
- Lossy compression can soften fine details and introduce artifacts on text-heavy images.
- Very large images may exceed browser canvas limits.
- Screenshots and images with sharp text compress less efficiently than photos.
Frequently asked questions
Common questions about Image Compressor
How much can I compress an image?
It depends on the content. Photos usually shrink noticeably — often by a third or more — while screenshots and images full of sharp text compress less. The tool always shows your actual before/after sizes.
Will compression reduce image quality?
JPEG is lossy, so some fine detail is discarded. At 70% quality the change is usually hard to notice on photos, but text and sharp edges can soften slightly. Compare the preview before downloading.
What happens to PNG transparency?
The output is a JPEG, which cannot store transparency. Transparent areas become a solid background in the compressed file. Keep the PNG original if you need transparency.
What image formats are supported?
JPG, PNG, and WebP images can be loaded and re-encoded as JPEG. The output format is always JPEG.
Can I compress very large images?
There is no server-side limit, but very large images (tens of thousands of pixels) can exceed the browser's canvas limits. If that happens, the tool reports that the image could not be processed.
Are my images safe to compress here?
Yes. Compression happens locally in your browser and your image is never uploaded.
Why does a transparent PNG turn black or white when compressed?
This tool compresses by re-encoding images to JPEG at 0.70 quality. Because JPEG has no alpha transparency channel, transparent pixels are composited onto a solid background (typically black or white). Keep the original PNG if transparency is required.
How does browser canvas compression differ from MozJPEG or Guetzli?
Browser canvas compression uses your operating system and browser's built-in JPEG encoder. It is instant and private because it runs locally in JavaScript, whereas server-side encoders like MozJPEG run heavier iterative quantization algorithms at the expense of CPU time.
Does recompressing an already compressed JPEG reduce its size further?
Repeatedly compressing a JPEG causes generation loss (visual degradation) with diminishing size returns. For best results, always compress from the original high-resolution master image.
Can I compress vector SVG or animated GIF files?
No. Vector SVGs contain mathematical XML paths and animated GIFs contain multi-frame palettes. This tool is designed specifically for raster photo formats (JPEG, PNG, WebP).
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