image tool
Image compressor
The only honest test of a compression setting is the picture itself. The original and the compressed copy share one frame under a divider you drag, with both file sizes printed on top of them, so you decide by looking rather than by guessing at a slider.
Runs on your device. Nothing is uploaded.
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How to use it
- 1
Drop the images
A compressed copy appears immediately at the default quality. There is no button to press to see a result.
- 2
Drag the divider
Original on the left of the line, result on the right. Drag it across the areas you care about, then use View at 100 per cent for fine detail.
- 3
Set the quality, or ask for a size
Around 0.8 is where most people stop seeing a difference on photographs. The advanced options take a target in kilobytes instead.
- 4
Compress and download
Every image goes through the same settings, and each row shows what it cost with its own save button.
The picture is the test, not the number
A quality value means nothing on its own. The same 0.8 produces an invisible change on a soft photograph and obvious mush on a screenshot full of text, because lossy encoders throw away high frequency detail first and text is nothing but high frequency detail. Putting the two versions in one frame under a divider is how Squoosh made this legible, and it is the only way to answer the actual question, which is whether anyone will notice.
Resizing beats compressing
A three thousand pixel photograph shown in a five hundred pixel column carries roughly six times more data than the screen can use. Capping the longest edge to about the size it will be displayed at usually saves more than any quality setting and costs nothing visually, because the pixels being thrown away were never going to be drawn. Do that first, in the advanced options here or in the resizer, and then compress what is left.
Asking for a size in kilobytes
Sometimes the requirement is a number, not a look: an upload form that refuses anything over 200 KB, or a page budget you have to fit. Give the tool a target and it searches for the highest quality that fits underneath it. When no quality setting is low enough, which happens with noisy photographs at full resolution, it starts giving up pixels as well and tells you the size it landed on, rather than quietly missing the target.
Why AVIF is not on the list
Every current browser can display AVIF, and none of them can write one from a canvas. Encoding is simply not exposed by the canvas API, which is why tools that offer AVIF ship a compiled encoder of their own weighing megabytes. This tool refuses to pretend: if your browser ever gains the ability, the button appears by itself, because the list is built by asking the browser what it can actually encode.
Limits
- Compression is lossy. Push the slider far enough down and you will see blocking around edges and text before you see it anywhere else.
- Re-compressing a file that was already compressed adds a second round of damage. Always start from the original.
- JPEG has no alpha channel, so transparency is filled with white when you choose it.
- No browser can write AVIF from a canvas, so only WebP and JPEG are offered where the browser supports them.
- Twenty four images in one go, held in your device's memory.
What it does not do
- It does not do lossless PNG optimisation, so a flat graphic is better left as the PNG you already have.
- It does not build a zip. Files save one at a time.
- It does not keep EXIF, GPS or colour profiles. Everything outside the pixels is dropped.
Questions people ask
What quality should I use?
Around 0.8 for photographs, which is roughly where the eye stops noticing on ordinary content. Go lower for a background image nobody studies, and higher for anything with fine text, logos or hard edges, because that is where lossy artefacts appear first. The comparison divider settles it faster than any rule of thumb.
Why did my PNG get bigger as a WebP?
Because a flat graphic with few colours compresses extremely well as PNG, and pushing it through a photographic encoder can cost more than it saves. Logos, icons, diagrams and screenshots of text belong in PNG. This tool tells you when the output grew, and the right answer in that case is to keep the file you already had.
Does compressing twice make it smaller?
A little, and it damages the picture each time. Lossy compression discards information permanently, so a file compressed three times carries three rounds of artefacts stacked on each other. Always compress from the original rather than from a previous export, and keep the original somewhere, because there is no way back.
How close does the target size get?
It searches the quality range for the highest setting that lands at or under your number, so the result never exceeds what you asked for and normally sits within a few per cent of it. If quality alone cannot get there, the pixel size comes down too, and the tool says so rather than silently returning something too large.
Is WebP safe to use everywhere?
On the web, yes, every current browser displays it. The exceptions are older software outside the browser: some print workflows, some content systems and some email clients still expect JPEG. If you are handing the file to a system rather than to a page, JPEG remains the safe choice, and the size difference is usually small.
Will it strip the location data from my photos?
The image is decoded and redrawn onto a canvas, which holds pixels and nothing else, so EXIF, GPS and colour profile blocks are not written into the output. The advanced panel names what the source was carrying so you can see what was dropped. If removing location is the whole point, confirm with a metadata viewer.
Is my photo uploaded?
No. Everything runs in this page, and after it has loaded no network request is made at all. The encoding happens in a background worker on your own device, which is also why a large batch makes your laptop fan spin rather than somebody else's server.
Use the smaller image
Take what you made here into flyers.
Create a flyer with OneCraftRelated tools
- Image resizerResize a batch of images to an exact width, height or percentage. Fit, fill or stretch, with a stepped downscale that keeps detail. Nothing is uploaded.
- Convert an imageSee your own picture measured in PNG, JPEG and WebP before you choose, then convert. Transparency is handled deliberately, and HEIC is explained.
- Image to base64Turn an image into a data URI for CSS, HTML, Markdown or JSON, with the character count, the gzipped cost, and a verdict on whether it should be inlined.
- Extract a frame from a videoOpen a video, jump with a filmstrip, step one frame at a time and save the exact frame as PNG, JPEG or WebP at full resolution. Nothing is uploaded.
Written and checked by the OneCraft team. Last checked .