Image converter that resizes as well as converts, entirely in your browser

No, and nothing is fetched either. Every step, including the resizing, runs on your own device using the browser's built in image handling. There is no upload, no sign up and no external library loaded, which is also why the tool cannot stop working because somebody else's server did.

Resizing is where nearly all of the saving comes from, and this tool does both in one pass. Converting a six thousand pixel photograph to a modern format still leaves a six thousand pixel photograph. Take the longest edge to 1920 for a website and the file falls dramatically before the format has contributed anything.

WebP for almost everything, because it is widely supported, holds transparency and compresses well. AVIF when you want the smallest possible file and can accept slower encoding. JPEG for email and older software. PNG only when you genuinely need lossless quality or transparency, since it produces much larger files than the alternatives.

Eighty to eighty five per cent suits most web images, where the loss is hard to see outside a side by side comparison. Below about seventy you start to notice banding in smooth gradients such as skies. If you have a file size to hit instead, use the target size field and the tool finds the highest quality that fits.

JPEG cannot store transparency, so those pixels must become a solid colour. Most converters fill them black without asking, which is rarely what anyone wants. This tool asks and defaults to white. To keep the transparency, choose WebP or PNG instead, since both support it.

No, and that is deliberate. Camera model, timestamp and any GPS coordinates are dropped during conversion. For web use that is what you want, since a photograph taken at home can otherwise publish your address. If you need metadata kept for archival purposes, use a desktop tool rather than this one.

AVIF achieves its smaller files by doing considerably more work per pixel, which takes time in a browser where a build server would not notice. On a large batch the difference is obvious. WebP gives you most of the size benefit for a fraction of the processing, which is why it is the default here.

The tool tests whether your browser can encode AVIF and disables the option when it cannot, rather than letting you select it and fail. Older browsers and some managed corporate devices are the usual cause. WebP is the right choice in that situation and the difference in file size is smaller than most people expect.

Fifty at a time, though the practical limit is your own device. Very large images or long batches consume memory, and a phone will struggle before a laptop does. Twenty at a time is comfortable almost anywhere. Files are processed one after another rather than all at once, specifically so a large batch does not overwhelm the browser.

Search engines read image filenames as a signal of what the picture shows, and a camera gives you a serial number that says nothing. Renaming is easy at this stage and awkward afterwards, because changing a filename on a live site breaks every link pointing at it. Type a description once and the whole batch is renamed in order.

Instagram square is 1080 by 1080, portrait is 1080 by 1350, and stories and Reels covers are 1080 by 1920. Facebook and LinkedIn posts sit around 1200 by 630, Pinterest suits 1000 by 1500 and a YouTube thumbnail is 1280 by 720. All are presets here, and each crops from the centre so you decide what survives rather than the platform deciding for you.

Some information is discarded by JPEG, WebP and AVIF, which is how they achieve their file sizes, but at the recommended settings the difference is not visible in normal viewing. PNG discards nothing at all. Resizing also removes detail by definition, which is why the presets never enlarge an image that is already smaller than the target.