🔒 100% Private — Files Never Leave Your Device

Compress PDF Online — Reduce File Size Free, No Upload

Reduce PDF file size directly in your browser — choose Light cleanup for text-based documents (preserves vectors and text selection) or Smaller file mode for scans and photo-heavy PDFs (up to 90% reduction). Set optional size targets, compress multiple PDFs in batch, compare before-and-after sizes, and download individually or as ZIP. Unlike iLovePDF, Smallpdf, and Adobe Acrobat Online, your files are never uploaded to any server — all compression runs locally on your device.

✓ Batch files ✓ Size comparison ✓ Works offline ✓ No watermarks

Uses pdf-lib and PDF.js (open-source libraries) for browser-based compression. No server uploads, no file retention. Last updated: April 2026.

1. How should we shrink your PDF?

Keeps text sharp and selectable — good for forms and reports. The file may only get a little smaller.

Optional target (smaller file mode only)
or

Leave blank to use the strength buttons above. If you fill both, max MB is used. Targets can take longer.

Quick guide

  1. Choose a mode — Light cleanup is safest for text. “Smaller file” helps most with scanned or photo PDFs.
  2. Add PDFs — They stay on your computer until you compress.
  3. Click Compress PDFs — Wait for the size comparison, then download.
  4. Try again? — Change options and compress again; your files stay in the list until you remove them.

Light cleanup tidies the file but often saves only a little space. Smaller file redraws each page as a picture — much smaller for scans, but text may look softer and copy/paste can get worse. Skip “smaller file” for important contracts unless you’ve checked the preview.

2. Add PDFs
📄
Drop PDFs here or click to browse
Nothing runs yet — files are only listed until you press Compress PDFs below.

Add at least one PDF, then click here. You can change options above and compress again without re-uploading.

Understanding PDF compression on this page

PDFs mix vector text, fonts, embedded images, and metadata. Light cleanup rewrites the document with pdf-lib, clears common metadata fields, and saves with object streams — vectors stay vectors, so savings are often small if the file was already lean. Smaller file uses PDF.js to render each page and embeds JPEGs — often dramatic for scans and photo-heavy PDFs, but pages become images, so text can look softer and copy/search may suffer.

For a longer privacy-focused guide, read how to compress a PDF on the DoItSwift blog.

Light cleanup vs Smaller file

Comparison of Light cleanup and Smaller file compression
Mode Best for Trade-off
Light cleanup Forms, reports, crisp text Often modest file reduction
Smaller file Scans, photos, huge attachments Lossy JPEG pages; check output before deleting originals

Optional targets (max MB or shrink %) apply only in Smaller file mode; they trigger extra passes to approach your goal. If both fields are filled, max MB wins. Light cleanup ignores those fields.

How Much Can You Compress? Typical Results

Typical compression results by PDF type and mode
PDF type Original size Light cleanup Smaller file (balanced) Smaller file (maximum)
Text-heavy report (50 pages) 2-5 MB 1.5-4 MB (10-30%) 1-2 MB (40-60%) 500 KB-1 MB (70-80%)
Scanned document (20 pages) 10-30 MB 9-28 MB (minimal) 2-5 MB (70-85%) 1-3 MB (85-95%)
Photo-heavy presentation 15-50 MB 12-45 MB (10-20%) 3-10 MB (60-80%) 2-5 MB (80-90%)
Simple form / letter 100-500 KB 80-450 KB (5-15%) Similar or slightly larger Similar or slightly larger
Merged multi-source PDF 5-20 MB 4-15 MB (15-30%) 2-5 MB (50-70%) 1-3 MB (75-85%)

Key insight: Light cleanup works best when the PDF has redundant metadata, duplicate fonts, or uncompressed object streams. Smaller file mode works best on scans and photo-heavy PDFs where rasterizing to JPEG yields dramatic savings. Already-optimized PDFs may not shrink much with either mode.

When You Need to Compress a PDF

Email attachment limits

Gmail caps attachments at 25 MB, Outlook at 20 MB, and many corporate email servers at 10 MB. Compress your PDF to fit within these limits instead of using external file-sharing links that may expire or require accounts.

Government and university portals

Online submission portals frequently limit uploads to 2-5 MB per file. Passport applications, visa forms, university admissions, job portals, and tax filing systems all impose strict size limits. Compress scanned documents to meet these requirements.

After merging multiple PDFs

Merged PDFs accumulate duplicate fonts and metadata from every source file, making the output larger than expected. A 5+3+4 MB merge can produce a 15 MB file instead of 12 MB. Compress after merging for significant savings — typically 30-60% reduction. Use our PDF Merger first, then compress the result.

Website and app uploads

CMS platforms, e-commerce product listings, and document management systems often have PDF size limits. Compressing PDFs before upload reduces storage costs and improves download speed for end users.

Archiving and backup

Compressing PDFs before archiving saves significant storage space over time. A company generating 100 PDFs/month at 5 MB each saves 30+ GB/year with even modest compression.

WhatsApp and messaging

WhatsApp limits document sharing to 100 MB, but large PDFs are slow to send on mobile data. Compressing scanned documents from 20 MB to 2-3 MB makes sharing instant even on slower connections.

Which Compression Mode Should You Use?

Recommended compression mode by document type
Your PDF type Recommended mode Why
Contract or legal documentLight cleanupPreserves text selectability and search
Scanned pages / receiptsSmaller file (balanced)Already images — rasterizing loses nothing
Photo-heavy reportSmaller file (balanced)Biggest gains on embedded photos
Tax / government formLight cleanupMust preserve form fields and text clarity
University assignmentLight cleanup first, Smaller file if still too largeTry preserving quality first
Portfolio / design workSmaller file (custom, high quality)Adjust quality slider to balance visuals vs size
Merged multi-document PDFLight cleanupRemoves duplicate fonts and metadata from merge
Email attachment too largeSmaller file + target sizeSet target to match email limit (e.g., 5 MB)

General rule: Start with Light cleanup. If the result isn't small enough, try Smaller file at Balanced strength. Only use Maximum or set aggressive targets when file size matters more than visual quality.

How Browser-Based PDF Compression Works

Most PDF compressors (iLovePDF, Smallpdf, Adobe) upload your documents to cloud servers for processing. Your contracts, financial statements, identity documents, and medical records travel across the internet and are processed on someone else's infrastructure. For sensitive documents, this is a privacy risk.

DoItSwift compresses PDFs entirely in your browser:

Light cleanup mode

  1. The pdf-lib JavaScript library reads your PDF in browser memory
  2. It rewrites the document structure, removing redundant metadata and optimizing object streams
  3. Vector text, fonts, and images are preserved — the output is structurally identical but cleaner
  4. A new, smaller PDF is generated and offered for download

Smaller file mode

  1. PDF.js renders each page to an HTML Canvas at your specified quality
  2. Each rendered page is exported as a JPEG image at the selected compression level
  3. A new PDF is built from these JPEG pages using pdf-lib
  4. The result is typically 50-90% smaller but pages are now images (text becomes non-selectable)

Privacy proof: Disconnect your internet and try compressing a PDF. It works — because no server communication happens at any point. Server-based tools fail instantly when offline.

DoItSwift vs Other PDF Compressors

Feature comparison: DoItSwift vs iLovePDF, Smallpdf, Adobe Acrobat Online
Feature DoItSwift iLovePDF Smallpdf Adobe Acrobat Online
Files stay on device Yes — never uploaded No — server processed No — server processed No — Adobe cloud
Compression modes 2 (Light + Raster with quality control) 3 levels (no control) 2 levels 3 levels
Quality/sharpness control Yes — sliders for both No No No
Target file size Yes — set max MB or min % reduction No No No
Batch compression Yes — unlimited Limited (free tier) 2/day free Limited
Before/after comparison Yes — per file Yes Yes Yes
ZIP download Yes Yes Limited No
Works offline Yes No No No
Free tier limits None — fully free Daily caps 2 tasks/day Requires login

Where DoItSwift wins: Privacy (no upload), quality control (adjustable sliders), target file size, and unlimited batch processing. No other popular compressor offers all four simultaneously.

Where others win: Server-based tools handle extremely large files (100+ MB) faster and can apply advanced compression algorithms that aren't available in browser JavaScript. Adobe Acrobat also preserves PDF/A compliance and metadata more reliably. For everyday compression of documents under 50 MB, DoItSwift is faster, more private, and offers more control.

Split, merge, or export images

Still too big? Try Split PDF and compress parts separately, or Merge PDF after shrinking pieces. To get pictures out of a PDF, use PDF to JPG.

Related tools

Related guides

Frequently Asked Questions

Is Compress PDF free and unlimited?

Yes. You can compress as many PDFs as your device can handle with no signup, watermarks, or daily task limits. There is no paid tier hiding features — batch queue, ZIP download, and optional size targets are all included. Practical limits are your RAM, CPU, and patience for very large files. Because processing stays in the browser, there is no server-side quota to enforce.

Are my PDFs uploaded to DoItSwift servers?

No. pdf-lib and PDF.js run entirely in your browser; bytes are read with the File API and never sent to DoItSwift. You can disconnect from the internet after the page loads and compression still works for files already in the queue. That behavior is different from most online PDF tools that upload to cloud workers. Clear downloads and close the tab on shared computers if the documents are sensitive.

What is the difference between Light cleanup and Smaller file?

Light cleanup rewrites the PDF structure with pdf-lib, clears common metadata, and saves with object streams while copying existing pages — vectors and text stay selectable, but savings are often modest. Smaller file renders each page to a canvas and embeds JPEGs in a new PDF, which can slash size for scans and photos but makes pages raster images. Choose Light cleanup when fidelity and search matter; choose Smaller file when attachment size is the priority. The UI always shows before and after sizes so you can compare.

Will every PDF get smaller?

Usually, but not always. Already-lean PDFs may barely shrink in Light cleanup because there is little redundant structure left to remove. In Smaller file mode the output can occasionally be larger than the original if the source was highly optimized or if JPEG settings are too gentle for the content. The results list shows original size, new size, and percent change so you can spot outliers. Smaller file uses lossy JPEG per page. Keep originals until you have verified the compressed file opens and looks acceptable.

How do optional target size goals work?

In Smaller file mode you can optionally set a maximum output size in megabytes or a minimum shrink percentage. The tool may run multiple compression passes, adjusting JPEG quality (and related settings) to approach the goal when possible. If both fields are filled, the max megabytes goal takes precedence over the percentage goal. These targets are ignored in Light cleanup mode because that path does not rasterize pages. Large targets on huge inputs can take noticeably longer.

Can I compress multiple PDFs at once?

Yes. Add several PDFs to the queue, choose your mode and strength once, then click Compress PDFs to process the whole batch. Each finished file gets its own download link with a before-and-after size line. When you have more than one success, use Download all as ZIP to fetch compressed-pdfs.zip in one step. You can change options and run again without re-adding files until you clear the queue or results.

What are the output filenames?

Each output keeps the original base filename and adds -compressed.pdf before the extension so you do not overwrite your source by accident. If the input lacks a .pdf suffix, the tool still appends the suffix pattern to a sensible stem. Rename after download if your portal requires a specific naming pattern. Keeping the stem makes it easy to match outputs back to originals in a folder.

Do password-protected PDFs work?

Encrypted or password-protected PDFs may fail to load in the browser libraries until they are unlocked. Use Unlock PDF when you have the password, or decrypt with a trusted desktop tool, then compress the unlocked copy here. Do not share passwords in screenshots or support tickets. If unlock is not possible, you will need an authorized copy from the document owner.

What about very large PDFs?

The interface warns when you add a file over about 50 megabytes because raster mode can be slow and memory-heavy on long, high-resolution documents. Very large jobs may make the tab unresponsive for a while; avoid closing the tab until processing finishes. On low-RAM devices, try fewer files per batch or use Light cleanup first. If the browser crashes, split the PDF with Split PDF and compress parts separately.

Is there a monthly limit or account required?

No accounts are required and there is no monthly cap or premium gate. The tool is fully client-side, so there is no server-side metering of tasks. You still need a modern browser with JavaScript enabled and enough local resources for your file sizes. Corporate proxies that block CDN scripts may prevent PDF.js from loading — allowlist the CDN or try another network if raster mode never starts.

How do I compress a PDF to under 1 MB or 2 MB?

Use "Smaller file" mode and set an optional target in the "Try to stay under" field — enter 1 or 2 for your MB target. The compressor will adjust JPEG quality automatically across multiple passes to approach your target. For very large PDFs (20+ MB), you may need to use Maximum strength alongside the size target. Note that extremely aggressive compression may reduce text readability — always check the output before discarding the original.

Does compressing a PDF reduce quality?

Light cleanup mode does not reduce visual quality — it only removes redundant data and metadata while preserving the document exactly as-is. Smaller file mode converts pages to JPEG images, which introduces lossy compression. At Balanced strength (default), quality loss is minimal on screen. At Maximum strength, text may appear softer and gradients may show banding. The quality and sharpness sliders give you precise control over this trade-off. For important documents, always preview the compressed output before using it.