A suite of free image tools that run entirely in your browser — no uploads, no accounts, no watermarks.
SlimImg is a collection of eleven image tools — compression, format conversion, resizing, cropping, rotating, watermarking, and more — built around a single constraint: your files never leave your device. Every tool on this site processes images locally in your browser, which is why there is nothing to sign up for, no queue to wait in, and no file-size subscription tier.
SlimImg is an independent project maintained by a small group of developers and designers. We started it because the image tools we relied on kept treating simplicity as an upsell: upload limits, watermarks on free output, and account walls around a five-second task. We wanted the opposite, so we built tools that do one job well, ask for nothing, and get out of the way. You can verify the no-upload claim yourself: open your browser's developer tools, watch the network tab, and use any tool on this site.
Bruce Shang
Developer of SlimImg, working on browser-based image processing and front-end performance.
SlimImg is built and maintained by Bruce Shang. Every tool is tested by hand before it ships, and the editorial guides are written from direct use of the tools rather than from second-hand sources.
The traditional online image tool has a workflow that made sense a decade ago: you upload your file to somebody's server, their software processes it, and you download the result. That workflow has real costs. Your photos — family pictures, ID scans, client work — sit on infrastructure you know nothing about. Large files take as long to upload as they would have taken to process locally. Free tiers slap watermarks on output or cap you at three images a day.
What changed is that browsers became genuinely capable. Modern JavaScript engines and the Canvas API are fast enough to decode, transform, and re-encode a photograph in milliseconds — on the same machine that was previously used only to shuttle the file back and forth. SlimImg exists because that shift makes the old upload-and-wait model unnecessary for most everyday image work.
When you drop an image into any SlimImg tool, the browser reads the file with the standard FileReader API and decodes it into a bitmap. The image is then drawn onto a <canvas> element — the same rendering surface every web page uses — and re-encoded from there at your chosen quality, format, or dimensions. The result is handed back to you as a new file, generated entirely in local memory.
At no point in that pipeline is a network request involved. You can verify this yourself: open your browser's developer tools, watch the network tab, and use any tool on the site. No image data leaves your machine. This is also why the tools keep working when your connection drops, and why processing speed tracks your own hardware rather than a shared server's load.
Our privacy promise is short because it can be: we do not receive your images, we do not store your images, and there is no account system that could associate files with you in the first place. There is no server-side copy to leak, sell, or lose — the most secure upload is the one that never happens.
A side benefit of local re-encoding is that image metadata is handled for you: EXIF data such as GPS coordinates, timestamps, and device details is not carried through to the compressed or converted output. The full details of what the site does and does not collect are in our privacy policy.
Eleven tools share the same engine and the same privacy model. Each exists because we needed it ourselves and couldn't find a version we liked.
Shrink JPG, PNG, and WebP files with a global or per-image quality slider, live before/after comparison, and batch downloads.
Crop with pixel-perfect precision, lock to any aspect ratio, or start from presets for Instagram, Twitter/X, and LinkedIn.
Resize by percentage or exact pixels with aspect-ratio locking, and process whole batches in one pass.
Convert between JPG, PNG, and WebP with adjustable quality and a live preview of the resulting file size.
Rotate by any angle or straighten in 90° steps, flip horizontally or vertically, and fix sideways phone photos for good.
Turn Apple's HEIC photos into universally compatible JPG files — batch conversion with adjustable quality, entirely on your device.
Overlay text or logo watermarks with a nine-position grid, adjustable opacity and size, and batch support.
Resize images to the exact dimensions each social platform expects, with presets for every major network.
Create QR codes from text, URLs, email addresses, and phone numbers, downloadable as PNG or SVG.
Pick colors from any image and get HEX, RGB, and HSL values by clicking a pixel — ideal for building palettes.
Rasterize vector graphics to high-quality PNG at any resolution, with custom scale and background color.
Found a bug, need a format we don't support yet, or want to tell us which tool to build next? We read everything.
support@slimimg.com