PDFs grow large for predictable reasons. Scanned documents embed full-resolution images for every page. Presentations carry high-DPI graphics and photographs. Reports exported from design tools include uncompressed assets. The result is a file too big for an email attachment, too big for a government portal, and slow to load on a phone. PDF Cloak compresses your files locally in the browser — free, no signup, and the file never leaves your device. You can even tell it the exact size you need and let it find the settings for you.

When to use this tool

Upload limits are the top motivator. Job applications, visa portals, exam registrations, insurance claims, and government forms routinely demand files under a specific size — 100 KB, 200 KB, 500 KB, or 1 MB. You do not control the original file's size, but you can compress it to fit before submission. That is exactly what Target size mode is for.

Email attachments are the second trigger. Most providers cap attachments between 10 and 25 megabytes, and a scanned multi-page document blows past that easily. Compression brings the file under the limit without splitting it across multiple emails.

Long-term storage also benefits. If you archive receipts, manuals, or records as PDFs, compressing them first saves meaningful disk space over hundreds of files. Web publishing rounds out the use cases: a 15 MB product datasheet that compresses to 2 MB loads noticeably faster for your visitors.

Pick the right mode

The tool offers four modes, and the honest tradeoff between them matters more than any slider:

Lossless. Strips metadata and repacks the file structure. Nothing visible changes, and text stays fully selectable and searchable. Gains are modest — typically a few percent — but they cost nothing. Use this for contracts, anything you'll need to copy text from, or files that are only slightly over a limit.

Balanced. Rebuilds each page as a 150 DPI image at good JPEG quality. Scanned documents and image-heavy files often shrink 60 to 90 percent, and pages still look sharp on screen and in standard printing. Text in the output is no longer selectable.

Strong. Same approach at 96 DPI and lower quality. Maximum squeeze for when size matters more than crispness — think portal uploads where the document just needs to be legible.

Target size. You enter the size you need in KB. The tool first checks whether a lossless pass already fits (if it does, you keep your text layer — the best possible outcome). If not, it samples a few pages at several resolution and quality combinations, estimates the full document size at each, and encodes at the strongest settings that fit under your target. If even the most aggressive settings can't reach the number you asked for, it says so plainly and hands you the smallest file it could make. No silent failures, no fake results.

How the compression actually works

In the image-optimized modes, each page is rendered to a high-quality canvas in your browser, re-encoded as a JPEG at the mode's resolution and quality, and rebuilt into a fresh PDF. This is the same technique professional tools use for scanned-document optimization, and it is why the reductions can be dramatic: a 600 DPI scan stored at full resolution carries far more pixels than anyone needs for reading.

It is worth being honest about limits. Text in a PDF takes up almost no space — a page of body text might be 2 to 5 kilobytes. A 50-page text-only contract has nothing large to shrink, and rebuilding it as images would make it bigger, not smaller. The tool detects this: if the image rebuild comes out larger than the lossless pass, it returns the lossless result automatically. Compression is most effective on files where images dominate — scanned paperwork, photographic reports, presentations, and image-to-PDF conversions.

Common issues

Text not selectable after compressing. This is the expected behavior of Balanced, Strong, and Target size modes — pages are rebuilt as images, and images have no text layer. If you need selectable text, use Lossless mode, or keep the original alongside the compressed copy.

Visible quality loss on photos. Strong mode and low targets will show JPEG artifacts in photographs at high zoom. The Balanced default is chosen to be visually transparent for screen reading and ordinary printing. If you are compressing for print, check the output at full zoom before committing.

Re-compressing an already optimized file. Running the tool again on its own output yields little further reduction and adds another round of lossy encoding. If you want to try a different setting, start from the original file.

The target seems impossible. A 40-page document cannot become 50 KB — there is a physical floor to how small legible pages can get. When the tool reports the target as unreachable, the floor-quality file it produced is still the smallest version possible; consider splitting the document and compressing the parts separately.

What to expect from our tool

Load your PDF, pick a mode, and press compress. In Target size mode you'll see quick presets for the common portal limits (100 KB, 200 KB, 500 KB, 1 MB) or you can type any number. A progress bar tracks each page as it is processed; multi-pass target searches show which pass is running.

Processing happens entirely on your device. A 20-page scanned document typically finishes in a few seconds. Image-heavy files with 100 or more pages may take longer, depending on your hardware. You will see a progress indicator but no upload bar — there is no network traffic at all, which you can verify in your browser's developer tools.

The result downloads as a new PDF with a before/after size comparison and the exact settings used. Your original is never modified. If the first attempt was too aggressive, pick a gentler mode and run it again from the original file.