Compress · Local Processing
PDF Compressor — No Upload, Fully Private
Compress PDF without uploading your file.
Compress PDF online instantly — no upload, no signup, fully private.
✔ No upload
✔ No server processing
✔ 100% client-side
Shrink PDFs for email, form uploads, and cloud storage — all without handing the file to a server. Your browser reads the PDF, re-encodes its images at a lower bitrate, and saves the smaller copy straight to your device. No uploads. No storage. No signup, no watermark.
Scanned PDFs typically drop 70–90% in size after a compression pass; text-heavy documents drop 10–30%. The mode you pick decides the trade-off between shrinkage and fidelity — conservative modes keep text searchable, aggressive modes maximize savings. For the deeper writeup on the fidelity side of that choice, see our notes on compressing PDFs without losing quality.
memoryProcessed in your browser
cloud_offNo upload, no storage
compressUp to 90% smaller
blockNo signup, no watermark
✔ You can verify this in DevTools — no file data ever leaves your browser
If image files would suit you better, try our PDF to JPG converter — same no-upload flow.
What this compressor actually does
Four things. No fine print. This works as a private PDF compressor, where everything happens locally on your device — a practical way to compress PDF without upload.
memory
Client-side compression
Re-encoding runs in your browser's PDF engine.
cloud_off
No file storage
The PDF is never persisted on our servers.
shield
No server access to your file
The source bytes never reach our backend.
tune
Multiple compression modes
Keep text searchable, or maximize shrinkage.
How it works
Three steps. Compression runs on your device — no upload at any point.
1
Your file stays in your browser
Pick a PDF with the file picker or drag it in. Your browser reads it into memory via the File API — no network request, no temporary server copy, no server access to the file.
2
Compression happens locally
Your browser analyzes the file with PDF.js on your device, re-encodes the image streams at a lower resolution or JPEG quality, and rebuilds the PDF with pdf-lib. Your CPU does the work, so the bytes never need to travel to a server.
3
Only the smaller file is downloaded
The compressed PDF saves straight to your disk. Close the tab and nothing remains — no history, no account, no cache we can replay.
When should you use a PDF compressor?
Common use cases for compressing PDFs include email attachments, web uploads, cloud storage, archival, and fast sharing. Below are the everyday moments where shrinking a PDF is the simplest way forward.
mailEmail attachment limits
Gmail caps attachments at 25 MB, Outlook at 20 MB, and many corporate mail servers at 10 MB. A PDF compressor gets a 40-page scanned report under the cap without splitting it into multiple mails or using an external link service.
uploadWeb form upload limits
Loan applications, insurance portals, school enrolment forms, and tax-filing sites frequently enforce hard caps like 5 MB or 10 MB per document. Shrink the PDF first and the upload just works — no calls to IT, no rescanning.
cloudCloud storage quotas
Free tiers on Dropbox, Google Drive, and iCloud fill up fast with scanned PDFs. Compressing before upload reclaims space without deleting documents you want to keep.
archiveArchiving documents long-term
For receipts, invoices, and records you need to keep but rarely open, a smaller PDF keeps your archive manageable. Mixed or Smallest mode is fine here — searchability trade-offs don't matter for documents that just need to exist.
boltFaster sharing on slow connections
Travel Wi-Fi, mobile tethering, and rural broadband all reward smaller files. A PDF compressor cuts upload time proportionally — a 90% smaller file uploads 10× faster.
Compression modes — which should you pick?
Different PDFs compress best with different strategies. The right mode depends on whether you need text to stay searchable, whether the source is scanned, and how aggressively you want to trade fidelity for file size.
Keep Text & Layout
Conservative mode. Text stays searchable, vector graphics stay sharp, only embedded raster images are re-encoded. Typical savings: 10–30% on text-heavy documents. Best pick for contracts, research papers, product manuals, or anything a reader will search.
Mixed Documents
Balanced mode. Flattens pages to a single raster layer at medium DPI. Text loses selectability but visual fidelity stays strong. Typical savings: 40–60% on documents with a mix of text and images. A reasonable default when you don't know the source.
Scanned PDF
Aggressive mode tuned for image-based PDFs — scans, photos of documents, or mobile captures. Re-encodes at higher JPEG compression, lower DPI. Typical savings: 70–90% on scanned source material. Text OCR would still work in a separate pass if needed.
Smallest File / Target Size
Maximum-reduction mode or a specific target cap (Under 1 MB, 2 MB, 5 MB). Auto-tunes DPI and JPEG quality to hit the file-size budget. Visual quality degrades gracefully — fine for archives and form uploads where hitting the cap matters more than print-quality fidelity.
Compress vs Reduce vs Optimize PDF — what's the difference?
Three terms that sound alike but mean different things when you're looking at a PDF file. Here's a plain-language comparison so you can pick the right approach for your document.
compressCompress PDF
The most common action. Reduces file size by re-encoding embedded images at lower resolution or higher JPEG compression, and rewriting the PDF structure more efficiently. Best for sharing, email, and web uploads. Trade-off: some quality loss on images depending on the mode. If maintaining visual clarity is important, consider compress PDF without losing quality before sending or archiving your file.
straightenReduce PDF size
A general term. In practice it usually means the same thing as "compress" — you end up with a smaller file — but it can also cover lighter cleanup work (removing unused objects, stripping metadata, flattening form fields). Most tools use "reduce PDF size" and "compress PDF" interchangeably, including the reduce PDF size without upload flow on this page.
tuneOptimize PDF
More advanced. Focuses on the PDF's internal structure — linearization for fast web viewing, font subsetting, downsampling only where justified, stream reordering. The goal is performance (load time, streaming over the web) rather than raw size reduction, though the optimized file is usually smaller too.
Why this is different from a typical online PDF compressor
Most tools upload your PDF to a server for processing. This one runs entirely in your browser — no network transfer of file content, no intermediate storage. Even if files are deleted later, they still pass through infrastructure you don't control. You can confirm this yourself using your browser's network tab — no file data is ever transmitted.
Why compressing PDF without uploading matters: every upload expands the privacy risk. The document ends up on a server you can't inspect, subject to its retention policy, logs, and breach exposure. Handling it in the browser keeps the data under your control — the file stays on your device, and the service you're using has nothing to store, forward, or leak. If you need to move the compressed PDF afterwards, a private file sharing flow is a better fit than a mail attachment.
Most tools upload the file
Your PDF hits a server you can't inspect. Retention policies, access logs, and breach exposure all depend on the vendor's discipline — not on anything you can check.
Everything runs locally on your device
The PDF bytes stay in your tab from start to finish. Analysis, re-encoding, and rebuild all run on your CPU through standard browser APIs — no server processing step.
You can verify this in browser DevTools
Open DevTools → Network, run a compression, and inspect every outgoing request. None of them carry your file data. The page itself loads HTML/CSS/fonts from our origin; the PDF payload never appears in the waterfall.
Works with the network disconnected
Load the page, switch to airplane mode, then run a compression. It still completes — direct proof that the file bytes never had to travel. No server round-trip is in the critical path.
When a private PDF compressor matters
Situations where running compression in the browser is worth the slight compute trade-off — because avoiding cloud uploads is the whole point.
gavelSensitive documents
Contracts, medical records, tax filings, or financial statements shouldn't travel through an unknown server just to shave a few megabytes. Compress locally, keep the source on your device, and share the smaller file through a channel you actually control.
policyPrivate files under review
Drafts, internal memos, redacted reports, or pre-release decks need to stay inside the author's device until they're cleared to go out. A client-side compressor lets you produce a smaller version for email without a round-trip to a third-party service.
wifi_offOffline workflows
Restricted networks, airplane Wi-Fi, or air-gapped research environments where uploads are blocked or slow. Because the compression runs in your browser, the tool works the same whether you're online or not.
cloud_offAvoiding cloud uploads
Policy-driven reasons (GDPR, HIPAA-adjacent workflows, company rules against third-party uploads) or simple preference. Compressing PDF without uploading means there's no server to audit, no data-processor agreement to sign, and nothing to delete afterwards.
boltQuick shrink before sending
Need to drop a large PDF under a recipient's attachment cap right now? Compressing in-browser is faster than waiting on an upload/download round trip — and there's nothing to clean up from someone else's server afterwards.
shareThen share only what you mean to
Once you have the smaller PDF, pair the tool with secure file transfer for private file sharing — the recipient gets the compressed PDF and nothing sits on a mail server as a plaintext attachment.
Related tools
Frequently asked questions
Can I compress PDF online without uploading?
Yes. Your file stays entirely in your browser: the PDF is read via the File API, analyzed with PDF.js, re-encoded at a lower resolution or bitrate, and rebuilt locally with pdf-lib. No request carries the file bytes, so there is no server access to the document at any point — a true in-browser flow you can verify in DevTools → Network.
Does my file leave my browser?
No, the file never leaves your browser. It lives in memory for the duration of the compression and is discarded when you close the tab. There is no upload, no temporary server copy, and no server access at any point — the only outbound requests the page makes are for its own static assets (HTML, CSS, fonts, icons).
Is client-side PDF compression safe?
Yes — it's safer than the server-side alternative. Because there is no upload, there is no server that can log, retain, or accidentally leak your PDF. Every transformation happens in your browser, so the usual risks of online PDF compressors (vendor retention, breach exposure, access logs you can't audit) don't apply. Endpoint security still matters — keep your browser up to date and avoid running the compressor on a machine you don't trust.
Is this a private PDF compressor?
Yes, this is a private PDF compressor in two concrete senses. First, no upload: your browser processes the file locally, so the PDF bytes never reach our infrastructure. Second, no account: there is no login, no server-side history, and no cached copy of what you compressed. A page refresh brings you back to an empty compressor, and nothing about the session is recoverable from our side — because we never had it.
What happens to my file after compression?
After compression, nothing remains on our side. The PDF is held only in your browser's memory during the run and is released when you close or reload the tab. The compressed PDF downloads straight to your device's Downloads folder. We don't keep the source PDF, don't keep the compressed copy, and don't maintain a session history — there is no server access to any of it.
How much can this reduce PDF file size?
Typical reductions depend on the source. Scanned PDFs commonly shrink 70–90% because their embedded images have the most room for re-encoding. Text-heavy PDFs shrink 10–30% because the text stream is already small. Mixed documents land in between — usually 40–60%. Running the conservative "Keep Text & Layout" mode first and switching to "Smallest" only if needed is a good rule of thumb.
Does compression reduce quality?
It depends on the mode you pick. The "Keep Text & Layout" mode preserves searchable text and vector graphics — text stays crisp and selectable, only embedded images are re-encoded. More aggressive modes (Mixed, Scanned, Smallest) flatten pages to images and re-encode at lower bitrates, which trades visual fidelity for file size. Because this is a private PDF compressor running entirely in your browser, you can experiment with modes without re-uploading anything. For the deeper writeup on fidelity-preserving compression, see compress PDF without losing quality.
Is there a size limit?
The practical limit is your device's available RAM, not a hard-coded cap. Very long PDFs (hundreds of pages) or high-resolution scans may slow down or stall on memory-constrained machines. If that happens, process the document in smaller ranges or pick a less aggressive mode. Because compression runs locally, there is no server-side upload size or request-timeout restriction.
How do I share the compressed PDF privately?
Send it through an end-to-end encrypted link instead of attaching it to email. For private file sharing, the server only ever holds ciphertext, the recipient decrypts in their own browser, and the link can be set to expire or self-destruct on first read.
How to compress PDF on Windows?
Open this PDF compressor in any modern browser on Windows — Chrome, Edge, or Firefox all work the same way on Windows 10 and Windows 11. Pick a PDF with the file picker or drag it into the page, choose a compression mode, and download the smaller file to your Downloads folder. There is no Windows installer, no administrator permission, and no driver setup — everything runs inside the browser's tab. If you also need to combine several PDFs before compressing, merge them online first.
How to compress PDF on Mac?
On macOS, open the compressor in Safari, Chrome, or Firefox and drop your PDF into the page. The compression runs locally on the Mac's CPU using standard browser APIs, so there is no Mac app to install, no menu bar helper, and no upload to a server. The compressed PDF lands in your Mac's Downloads folder like any other file save. This is also a practical way to shrink a PDF on Mac without opening Preview, Automator, or a third-party desktop tool.
Can I compress PDF offline?
Yes. Load this page once with an active connection, then switch to airplane mode or disconnect your network — the PDF compression keeps working. All analysis and re-encoding happen in your browser, so after the initial page load the compressor does not need internet access to process files. This also serves as a direct demonstration that your PDF isn't being uploaded anywhere: if it were, offline compression wouldn't succeed.
Is PDF compression safe?
Yes — PDF compression is safe when it runs on your device instead of on a remote server. With this tool, the PDF never leaves your browser, so there is no upload log, no server retention window, and no third party that can read, replay, or leak the file. The compressed output is a standard PDF that opens in any PDF reader without risk. Endpoint hygiene still matters: keep your browser up to date and avoid running the compressor on a shared or untrusted machine.
Is this PDF compressor free?
Yes, this PDF compressor is free to use — compress PDF free, with no daily limit, no paywall, no signup, and no watermark on the compressed file. Because the compression runs in your browser, there is no server cost per job, which is why the free tier has no artificial caps. If you need images from the PDF instead, PDF to JPG and PDF to PNG are free under the same terms.
Can I compress large PDF files?
Yes, you can compress large PDF files — the practical limit is your device's available memory rather than a server-side upload cap, because the entire compression runs in your browser. A few hundred scanned pages is typical on a modern laptop; for very long dossiers, compress in smaller ranges or pick a less aggressive mode. If you're assembling several PDFs into one before compressing, merge them online first — the merge itself is also client-side.
Does it work on mobile?
Yes, the PDF compressor works on mobile — any modern browser on iOS (Safari, Chrome) or Android (Chrome, Firefox) can run the compression. Drop your PDF into the page, pick a mode, and the compressed PDF saves to your device's Downloads folder. Because everything happens in the mobile browser, there is no app to install and no account to create. Memory is tighter on phones than laptops, so for very long PDFs consider compressing in ranges.
What is the best PDF compressor?
The best PDF compressor for most people is one that respects your document. A good PDF compressor should offer multiple compression modes, preserve text searchability when you pick the right mode, be free and watermark-free, and should not upload your file to a server. This compressor covers all four: compression runs entirely in your browser, four modes are available (Keep Text, Mixed, Scanned, Smallest), exports carry no branding, and there is no signup or paywall. Use it as a general-purpose PDF compressor whenever you need smaller files without handing the source over to a third party.
How does PDF compression work?
PDF compression reduces file size by re-encoding the image streams inside the PDF (usually the biggest contributor to size), lowering their resolution or increasing their JPEG compression level. Text and vector graphics are usually already well-compressed by the PDF format itself, so the largest savings come from scanned pages or photo-heavy content. In aggressive modes, the tool re-renders each page as a lower-DPI image and replaces the original — this flattens text but maximizes shrinkage. The PDF structure itself (fonts, metadata, object streams) is also tightened up as part of the rewrite.
Can I compress PDF online safely?
Yes — safety depends on where the work actually happens. Uploading your PDF to a remote server for processing means the file lives (even briefly) in infrastructure you can't audit. Running the job in-browser removes that risk entirely: the PDF bytes never leave your device, so there is no upload log, no retention window, and no third-party server that could be breached. Open DevTools → Network and verify for yourself that no request carries your file. Endpoint hygiene still matters — use a trusted device and keep your browser up to date.
Compress your PDF without uploading it.
Open the compressor, pick a mode, download the smaller PDF. No uploads. No storage. No server access to your file.
compressOpen the Compressor