100% local · no uploads · free

Compress PDF to 400KB

Hit an upload limit? Shrink your PDF to about 400KB while keeping text crisp and selectable.

Many web forms, court filing systems, and document management platforms cap uploads between 200KB and 500KB. Insurance claims and HR portals are frequent offenders.

The compressor rasterizes pages and re-encodes embedded images at progressively lower quality until the file fits. Text and vector elements remain sharp because they are preserved as-is wherever possible.

All compression runs entirely on your device using WebAssembly, so confidential contracts, financial documents, and medical records never leave your browser.

Compress PDF to 400KB →
  • Files never leave your device
  • No size limits
  • Free, no sign-up

How to compress pdf to 400kb

  1. 1
    Upload your PDF

    Drop your PDF into the secure browser dropzone. The file stays on your device — nothing is uploaded.

  2. 2
    Set 400KB as target

    Choose target-size mode and enter 400 KB as your limit. The engine will iterate to hit this cap.

  3. 3
    Download compressed PDF

    Click compress, wait a few seconds, and download the optimized file. Text stays selectable and sharp.

Frequently asked questions

Will text stay readable at 400KB?

Yes — the compressor targets embedded images specifically. Text and vector graphics (charts, logos, line art) remain perfectly sharp and selectable.

Is it private?

Absolutely. Everything runs locally in your browser via WebAssembly. Your PDF and its contents are never uploaded to any server.

What if my PDF is already under 400KB?

If your PDF is already smaller than 400KB, no compression is applied. You will get the original file back unchanged.

How does target-size mode work?

The engine iteratively adjusts image quality and resolution of embedded images, testing the output size after each step, until the result is at or below your 400KB target.

Can I compress multiple PDFs at once?

Currently the tool processes one PDF at a time, but you can quickly drop another file after the first finishes.

The real difference

Why KuroPDF exists

Every other PDF tool uploads your files to their servers. We think that is broken. Here is what we do differently - and what the alternatives actually cost you.

Nothing leaves your device

Files are processed in your browser using WebAssembly. Open DevTools → Network tab and verify: zero upload requests. Ever.

What competitors do instead:

Smallpdf, iLovePDF, and Adobe Acrobat all upload your files to their servers - your contracts, bank statements, and medical records pass through third-party infrastructure.

No file size limits, no daily caps

Process a 500-page PDF or batch-convert 200 photos. No cap, no throttle, no upgrade wall. Your device is the only limit.

What competitors do instead:

Smallpdf limits free users to 2 tasks per day. iLovePDF caps file sizes at 100MB. Adobe requires a $19.99/mo subscription for basic features.

Works completely offline

Install KuroPDF as a progressive web app. After the first visit, every tool works with zero internet - on a plane, in a bunker, wherever.

What competitors do instead:

Every cloud-based PDF tool stops working the moment your Wi-Fi drops. No connection = no work.

Real encryption, not security theatre

Password protection uses AES-256 encryption via a WebAssembly build of qpdf. The password never leaves your machine - there is no server to intercept it.

What competitors do instead:

When you 'protect' a PDF on Smallpdf or iLovePDF, your unencrypted file and password travel to their server, get processed, then get sent back. That is not security.

Free forever, no account needed

No login wall, no email harvesting, no 'continue with Google' popup. Open the site, use the tool, close the tab. Done.

What competitors do instead:

Adobe charges $239/yr. Smallpdf charges $108/yr. iLovePDF charges $84/yr. All require account creation to use basic tools.

Professional-grade codecs

MozJPEG for JPEG, OxiPNG for PNG, AVIF and WebP encoders - the same codecs used by Google and Mozilla. Not generic re-encoding.

What competitors do instead:

Most cloud tools use basic server-side encoders with less optimization control. You get worse compression at lower quality.

0 Files uploaded
0 Accounts required
$0 Price, forever
30+ Professional tools

Related tools

All PDF tools