KeroTools

Compress PDF Online — Reduce File Size Free & Private

Shrink a PDF to a smaller file size — right in your browser. Your file never leaves your device, and there are no watermarks or sign-ups.

No uploads — 100% privateRuns in your browserFree, no account needed

Drop PDF here or click to browse

PDF files only

Your file never leaves your device

Nothing to delete later

Secure connection

Works in every modern browser

How it works

  1. 1

    Add your PDF

    Drop the PDF onto the page or click to browse and select it.

  2. 2

    Compress

    Press Compress — the file is optimized in your browser to a smaller size.

  3. 3

    Download

    Save the smaller PDF instantly; compare it against the original size shown.

Why use this tool

Smaller files, fast

Cut a PDF down so it fits email limits and uploads in seconds.

Private by design

Compression runs locally in your browser — the file is never uploaded to a server.

Keeps it readable

Text stays sharp and selectable; images are optimized, not destroyed.

No watermark

The compressed PDF is clean — nothing is stamped onto your pages.

Works on any device

Phone, tablet, or computer — it runs in the browser you already have.

Instant download

The smaller file is ready in seconds and downloads straight to your device.

What does compressing a PDF do?

Compressing a PDF reduces the size of the file in megabytes while keeping the document itself intact — same pages, same order, same text. Most of a large PDF’s weight comes from embedded images and fonts, so a compressor re-encodes those more efficiently: high-resolution photos are down-sampled to a sensible size, redundant data is removed, and the file is rewritten in a leaner structure. The result is a document that looks the same on screen but takes far less space to store, email, or upload. Because this tool works entirely in your browser, the file is optimized on your own device and never sent anywhere.

When should you compress a PDF?

Compression is the answer whenever a PDF is too big for where it needs to go. Email providers reject attachments over a limit (often 20–25MB); job portals and government forms frequently cap uploads at 2–5MB; and a scanned document full of photos can balloon to tens of megabytes. Compressing brings the file under those limits. It also speeds up sharing over slow connections and saves storage when you archive many documents. If you have just merged several PDFs into one large file, compressing afterwards is the natural next step.

How to get the best results

The biggest savings come from PDFs that contain photos or scanned pages — those compress dramatically. A PDF that is mostly text is already small and will shrink less, which is normal. If the file must stay razor-sharp for printing, keep a copy of the original before compressing, since reducing image resolution is a trade-off between size and detail. For scanned documents, compressing after scanning (rather than scanning at an unnecessarily high resolution in the first place) usually gives the cleanest balance of size and legibility.

Limitations to be aware of

Compression cannot work miracles: a PDF that is already optimized, or one that is purely text, has little left to remove, so do not expect a huge drop every time. Reducing image quality too aggressively can make photos look soft, which is why a balanced level is used by default. Password-protected PDFs must be unlocked before they can be compressed, because the tool needs to read and rewrite their contents. And compression changes the file’s internal structure, so a digital signature that certifies the exact original bytes may show as invalid afterwards — that is inherent to how signatures work.

Common mistakes and how to avoid them

A frequent mistake is expecting a text-only PDF to shrink like an image-heavy one — it will not, and that is fine. Another is compressing a file that needs print-quality images and then being surprised the photos look softer; keep the original if print fidelity matters. People also try to compress a protected file and hit an error — unlock it first. Finally, running the same file through a compressor twice rarely helps; the second pass has almost nothing left to optimize and can even add a little overhead.

Using it on mobile and desktop

On a computer, drag the PDF straight from a folder and compress it before attaching it to an email — ideal for staying under size limits. On a phone, pick the PDF from your files or cloud storage; the whole process runs on the device, so you can shrink a document and upload it to a form without a computer. The layout adapts to the screen, and because there is no app to install, the same link works everywhere.

Why compress here instead of another site?

Most online PDF compressors upload your file to their servers, shrink it there, and promise to delete it later. This tool never uploads your file at all — the compression happens inside your browser, so a document that might contain a contract, an ID scan, or private records stays on your device from start to finish. There are no watermarks, no account walls, and no daily limits. It is also faster in practice, because you skip the upload-and-wait round trip entirely.

How it compares

FeatureThis toolTypical online PDF tools
File uploaded to a serverNever — compressed in your browserUsually uploaded
Watermark on outputNoSometimes
Account or sign-upNot requiredOften required
Daily / size limitsNoneCommon on free tier
PriceFreeFree / paid tiers
Works offline after loadYesNo

Features

One-click compression

No confusing settings — add the file and press compress.

Size before / after

See the original and reduced size so you know exactly what you saved.

Image optimization

Large embedded images are the main cause of bloat and are optimized first.

Keeps text selectable

Real text stays as text — it is not flattened into a picture.

No installation

Nothing to download or install — it works on the open web page.

Offline-capable

Once the page has loaded, compression works even without internet.

Arabic & RTL friendly

Full interface in eight languages, including right-to-left Arabic.

Secure by default

Served over HTTPS, with no file tracking and no third-party upload.

Who uses it

Job seekers & students

Get a CV or assignment under a portal’s strict upload limit without losing readability.

Office & admin teams

Send heavy reports and scans by email without hitting attachment-size caps.

Freelancers

Deliver a lighter proposal or invoice that opens quickly for the client.

Everyday users

Shrink a scanned document to upload to a government form — without sending it to anyone.

Frequently Asked Questions

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