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Image Optimizer & Converter
Compare appearance and file size before you save.
How to use
- Choose the images to convert.
- Choose the output format, quality and size, then convert.
- Inspect the images and file sizes, then save individually or as a ZIP.
Add images
Add up to 20 JPEG, PNG, or WebP images at once.
Drop images here
or
Supported: JPEG / PNG / WebP (up to 40 MB and 40 megapixels per image)
Your images are processed locally in your browser and are not uploaded to Rakuruno.
Settings are saved for 30 days. Image files are not saved.
Before and after preview
Select an image to preview it
Select an image to preview it
The converted preview will appear here
File size comparison
- Original
- —
- Converted
- —
- Difference
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Conversion settings
You can adjust every setting after choosing a preset.
Not saved
About this tool
- Images are opened, converted, and added to ZIP files locally in your browser. Image data is not sent to an external service.
- Converted images do not retain GPS location, EXIF, or other metadata. EXIF orientation is applied before re-encoding.
- Transparent areas are filled with white when you convert an image to JPEG.
ZIP creation uses fflate under the MIT license.
Try a use case and check the result
Check pixel resizing separately from the white background used when converting transparency to JPEG.
Example buttons replace the inputs and settings above with synthetic data and process it. Restore previous input steps back one example at a time. After trying multiple examples, repeat restore to return to your original input. This history is lost when the page closes.
Halve a solid red image
Input and settings
Solid red 64×32 px; PNG; 32×16 px bounds with aspect ratio retained.
Expected result
Saved PNG: 32×16 px; all 512 pixels are opaque red. PNG ignores the quality value.
Convert transparency to JPEG
Input and settings
Fully transparent 64×32 px PNG; JPEG quality 90.
Expected result
Saved JPEG: 64×32 px and white throughout. JPEG has no alpha channel, so the original transparency cannot be recovered.
How to read the result
Judge optimization by the actual input/output byte difference. A tiny PNG can grow when converted to JPEG. Bounds, aspect ratio and prevention of enlargement are separate settings.
Scope and limits
JPEG/PNG/WebP; up to 20 images, 40 MB and 40 megapixels each. Saved ZIP is limited to 96 MiB. JPEG/WebP are lossy and quality does not guarantee a fixed size. PNG ignores quality. Color management and resampling can change appearance; retain originals.
Compare every saved PNG RGBA value and decoded JPEG pixel against independent expectations. After multiple Undo steps, verify original files, selection, settings and converted outputs.
Continue with the next task
Resize 4000 × 3000 pixels without changing the aspect ratio
With both maximum dimensions set to 1600 pixels and aspect ratio preserved, a 4000 × 3000 image becomes 1600 × 1200 pixels. It fits inside the size limit rather than being cropped to a square.
Add an image, choose settings and convert it. Compare text, edges and file size before downloading. If you change settings, convert again to check the new result.
Frequently asked questions
Are my images uploaded to a server?
No. Images are opened, converted, previewed, and saved locally in the browser running this page.
Should I use JPEG or PNG?
JPEG is commonly used for photographs. PNG is useful when you need transparency or have graphics with text and sharp edges. Compare both appearance and file size before choosing.
Does the converted image keep location data?
No. Re-encoding removes GPS location, EXIF, and other metadata from the converted file.
Can I convert several images at once?
Yes. Add up to 20 images and process them in sequence with the current settings. Download all converted images together as a ZIP file.
Will conversion always make an image smaller?
No. The result depends on the image content, original format, quality, and dimensions. The tool warns you when the converted file is larger.
What happens to PNG transparency when I convert to JPEG?
JPEG cannot store transparency, so this tool fills transparent areas with white before encoding the JPEG.
Related tools
Share this tool
Share only the tool name and public URL. Your input and results are not included.
Inputs and storage
Keep any inputs or results you need before clearing. This browser saves only output format, quality, dimensions and related settings, not your working data or generated results. Site-data deletion or storage restrictions may remove settings. Settings are not restored when read 30 days or more after the last save.
Favorites and language preferences are stored separately and may be lost when site data is cleared. Tool resets and site-data deletion do not delete files already downloaded to your device.