I built a free image and PDF toolkit that runs entirely in the browser
Most "free online" image compressors upload your photo to a server, process it there and send it back. That works, but it means a copy of your file sits on someone else's machine, and the site pays for bandwidth and CPU, which usually ends in a daily limit or a watermark. I wanted a toolkit where none of that happens. The result is Compressly : an image compressor, resizer, converter, background…
Many free online image compressors transmit files to a server for processing, which stores a copy on their machine and may impose bandwidth or CPU limits. This results in daily restrictions or watermarks. Compressly offers a browser-based alternative, compressing, resizing, converting, removing backgrounds, upscaling, and handling PDF and Word files without any server involvement.
Users can compress to an exact file size, shrinking pixel dimensions if necessary. The canvas API encodes JPEG and WebP at a set quality level, but Compressly uses binary search to achieve the desired target size. Encoding occurs in a Web Worker using OffscreenCanvas.convertToBlob(), allowing multiple iterations without freezing the browser.
Smaller PNGs retain transparency through median-cut quantisation and optional Floyd–Steinberg dithering. AI background removal utilizes the ormbg segmentation model in Transformers.js, providing an AI mode for complex backgrounds and a non-AI mode for logos and signatures. PDF and Word tools manually write PDF 1.4, embedding fonts, images, and text, with DOCX files unzipped using DecompressionStream and DOMParser.
The editor allows converting between PDF and DOCX formats. Feedback is invited on the target size algorithm and background removal speed and quality.
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