Image Converter, Resizer & Compressor at a glance
- What it does
- Resize images, compress them and convert between PNG, JPEG and WebP in your browser. Photos are never uploaded - all processing is local.
- Where it runs
- Entirely in your browser — no data is uploaded
- Works offline
- Yes, once the page has loaded
- Cost
- Free, with no account and no usage limit
- Category
- Design & Colors
How to use the image converter
- Choose an image file from your device.
- Set the dimensions you need, or leave them to keep the original size.
- Pick an output format and adjust quality if you are exporting JPEG or WebP.
- Download the result. The original file is untouched.
Choosing a format
| Format | Best for | Transparency |
|---|---|---|
| WebP | Almost everything on the web. 25-35% smaller than JPEG at equal quality. | Yes |
| JPEG | Photographs where maximum compatibility matters - email, older software. | No |
| PNG | Screenshots, logos, line art, anything with sharp edges or transparency. | Yes |
| AVIF | Best compression available, but slower to encode and not universally supported. | Yes |
| SVG | Logos and icons, at any size. Not applicable to photographs. | Yes |
The rule of thumb: photographs to WebP or JPEG, anything with text or hard edges to PNG or WebP, logos and icons to SVG. Saving a screenshot as JPEG produces visible ringing around text and is the single most common format mistake.
What the quality setting does
JPEG and WebP are lossy: they discard detail the eye is least likely to notice. The quality slider controls how much.
The useful range is narrow. Quality 100 is nearly always wasteful - it typically doubles the file size for a difference nobody can see. Quality 80 to 85 is the sweet spot for photographs and is what most optimisation tools default to. Below 70, artefacts start showing around edges and in flat areas of sky.
One important caveat: lossy compression is not reversible, and re-saving compounds. Each edit-and-save cycle on a JPEG degrades it further. Keep an original in a lossless format and export lossy copies from it, rather than repeatedly editing the exported file.
Getting the dimensions right
Serving a 4,000-pixel photograph into a 600-pixel column wastes most of the bytes you send. The browser scales it down and the user pays for the difference.
Resize to roughly twice the display size to look sharp on high-density screens - a 600-pixel column wants a 1,200-pixel image. Beyond 2× the returns effectively vanish, and 3× is measurable only under scrutiny.
Practical maximums: full-width hero images rarely need more than 1,920 pixels wide; content images 1,200 to 1,600; thumbnails 300 to 600. If you need several sizes, generate them and use srcset so the browser picks the appropriate one.
Images and page speed
Images are usually the largest thing on a page, so they dominate the Largest Contentful Paint metric that Google uses as a ranking signal. Four things matter most:
- Correct dimensions - the single biggest saving available on most sites.
- Modern format - WebP over JPEG is a free 25-35%.
- Explicit width and height attributes, so the browser reserves space and the page does not jump as images load. Layout shift is itself a ranking factor.
- Lazy loading for images below the fold, using
loading="lazy". Never on your hero image, which should load as early as possible.
Why local processing matters for images
Photographs carry more than pixels. EXIF metadata routinely includes the exact GPS coordinates where a photo was taken, the device that took it, and the timestamp. Uploading an image to an online converter hands all of that to a third party along with the picture itself.
This tool reads the file with the browser's File API and re-encodes it through a canvas, entirely on your device. Nothing is transmitted. As a side effect, canvas re-encoding strips EXIF metadata, so exported images do not carry location data - useful before publishing a photograph taken at home.
Frequently asked questions
No. The file is read and re-encoded in your browser. Nothing is transmitted, which also means the tool keeps working offline.
WebP for the web - it is 25-35% smaller at comparable quality and every current browser supports it. Keep JPEG for email attachments and older software that may not read WebP.
80 to 85 for photographs. Quality 100 roughly doubles the file for no visible benefit. Below 70 the artefacts become noticeable.
Making an image smaller is fine - detail is discarded, not degraded. Enlarging cannot add detail that was never captured, so an upscaled image looks soft.
Yes, as a consequence of re-encoding through a canvas. Location and camera metadata do not survive, which is usually what you want before publishing.
Nothing you enter here leaves your browser
Image Converter, Resizer & Compressor does its work in JavaScript running on your own device. The page loads once, and after that there is no upload step and no server involved — which matters here because images carry metadata, and unreleased artwork should not be uploaded to convert it.
You can verify this rather than taking our word for it: load the page, disconnect from the internet, and the tool keeps working. Our privacy policy sets out what is and is not collected, and this guide explains why the distinction matters.