PDF Compress

No, your PDF never leaves your device. WikiPlus PDF Compress runs entirely in your browser using pdf-lib combined with an HTML5 canvas re-render pipeline. When you drop your file onto the tool, the browser reads it from your local file system into tab memory, parses the internal PDF structure, processes embedded images through the canvas encoder at whichever quality level you selected, and writes the compressed PDF back into browser memory for download. Not a single byte of your document travels over the network. There is no backend API, no cloud processing queue, and no analytics pipeline that ever touches your file content. All processing happens in your browser — nothing leaves your device. This local-only design is critical for the documents people most commonly compress: contracts containing confidential commercial terms, invoices listing pricing and banking details, medical records subject to privacy regulations, and scanned identity documents that are prime targets for theft. Sending any of these to a third-party compression service, even one that claims to delete files after processing, introduces a risk you cannot independently verify. With WikiPlus there is nothing to trust because there is no transmission at all. You can confirm this yourself: load the page, disconnect from the internet, then drop your file. Compression completes successfully because the entire pipeline runs offline after the initial page load. Reconnecting is only needed to visit the site in the first place.

The three levels control how aggressively embedded raster images inside the PDF are re-encoded. Text, vector graphics, and drawn shapes remain completely lossless at every level because they are stored as drawing commands rather than bitmap data. Low compression re-encodes images at a quality setting that is visually near-identical to the original. It is the right choice for printed brochures, design portfolios, or any document where photos will be scrutinised at full zoom. Expect file-size reductions of roughly 20 to 40 percent on image-heavy PDFs. Medium compression applies a moderate quality reduction that is unnoticeable at normal reading zoom but trims significantly more data. This is the recommended default for office documents, reports, and contracts that will be read on screen. File size typically drops 40 to 65 percent. High compression applies the strongest reduction, encoding images at the minimum quality that keeps text legible. It suits scanned forms, internal memos, or reference copies that will never be printed. Reductions of 65 to 80 percent are common. PDFs that consist almost entirely of vector text and no photos will see minimal size change regardless of the level selected, because there are no raster streams to re-encode. In those cases the size difference between levels may be only a few kilobytes. As a practical tip, try Medium first and check the preview — it covers most use cases without any visible quality loss.

No. WikiPlus PDF Compress targets only the raster image streams embedded within your PDF. The text layer, embedded fonts, vector drawings, annotations, hyperlinks, interactive form fields, and document metadata all pass through the pipeline completely untouched. The output PDF opens in any reader with exactly the same layout, font rendering, and page geometry as the original. Characters remain selectable and searchable. Copy and paste from the compressed file works identically to the source. This is an important distinction from other compression approaches, such as printing the PDF to a virtual printer driver, which rasterises every page into a bitmap and permanently destroys the text layer. WikiPlus compresses at the image-stream level inside the existing PDF structure, so the document remains a proper structured PDF rather than a collection of flat page images. One caveat applies to scanned documents: if your PDF was created by photographing or scanning a physical page without running OCR, every page is itself a raster image. Compressing at Medium or High levels will visibly reduce the quality of those scanned page bitmaps. If the scan is already borderline legible, use Low compression to preserve readability. For scanned documents where you need both small file size and a searchable text layer, run OCR first using a dedicated tool such as Adobe Acrobat or an open-source OCR application, then compress the resulting searchable PDF.

WikiPlus PDF Compress imposes no hard file-size limit. The practical ceiling is determined by the available RAM in your device, because the entire PDF must be loaded into browser memory for processing. On a modern laptop with 8 GB of RAM, PDFs of several hundred megabytes process without issues. The vast majority of documents people need to compress fall well below 50 MB: multi-page contracts, invoices, scanned ID documents, photo-rich reports, and marketing brochures all typically range from 2 MB to 30 MB. The tool is optimised for these common sizes and processes them in a few seconds, depending on the number of embedded images and the CPU speed of your device. If you try to compress an unusually large file and the browser becomes sluggish or the tab crashes, close other browser tabs to free RAM and retry. If the file is genuinely enormous, split it into smaller chunks using our PDF Split tool, compress each part separately, and merge them back with our PDF Merge tool. There is no daily quota, no account required, and no subscription to maintain. You can compress as many PDFs as you need in a single session and the tool remains free permanently. Password-protected PDFs that require a password to open are not supported — remove the password first with our PDF Unlock tool before compressing.