If your photo contains your face, your contract contains your salary, or your scanned PDF contains your Aadhaar — uploading them to an online tool is a privacy bet you can't verify. "Files deleted in 2 hours" is a marketing claim, not a guarantee. The only way to be sure your file isn't seen by anyone else is to use a tool that doesn't upload it in the first place.
We tested 12 image and PDF tools that process files entirely in your browser, fully offline, or via self-hosted infrastructure. Disclosure: ShrinkTo (made by us) is in this list. We've been honest about where competitors win — ImageOptim is the gold standard for Mac, Stirling-PDF has more raw features, and Squoosh has the best image fine-tuning UX.
Try ShrinkTo's privacy-first tools
Image compression + 27 PDF tools, all processing happening in your browser. Verifiable via DevTools — your file never uploads.
Side-by-side comparison (12 tools)
Quick scan of what each tool offers. ShrinkTo (our tool) is highlighted at the top — full reviews of all 12 are below.
| Tool | Type | Free tier | Privacy |
|---|---|---|---|
| ShrinkTo ⭐ | Browser-based | Unlimited | Browser-only (verifiable) |
| Squoosh | Browser-based (Google) | Unlimited | Browser-only (Google maintained) |
| ImageOptim | Mac desktop | Fully free | Fully offline |
| PDF24 desktop app | Desktop (Win/Mac) | Fully free | Fully offline |
| PDFsam Basic | Desktop (Win/Mac/Linux) | Fully free | Fully offline |
| Caesium | Desktop (Win/Mac/Linux) | Fully free | Fully offline |
| Trimage | Desktop (Linux) | Fully free | Fully offline |
| Stirling-PDF | Self-hosted (Docker) | Fully free | Self-hosted |
| Drawboard PDF | Web + native apps | Limited free | Web tools claim browser-only |
| ExifCleaner | Desktop (Win/Mac/Linux) | Fully free | Fully offline |
| Bulkresizephotos | Browser-based | Unlimited | Browser-only |
| PixelKnot / WhitelistedExifEdit (Mobile) | Mobile apps | Free | On-device |
How we tested
Each tool was verified to perform processing without server uploads using browser DevTools Network tab. We measured: privacy model (browser-based, fully offline, or self-hosted), feature breadth, free-tier limits, and ease of use for non-technical users.
Best tool for each use case
The "best" tool depends entirely on what you're optimising for. Pick from this list rather than reading every review.
Detailed reviews (12 tools)
ShrinkTo Our pick
shrinkto.comBest for: Image + PDF tools combined with browser-only privacy
Combines image compression and 27 PDF tools in one site, all running in-browser. Verifiable via DevTools Network tab — no outbound file requests. Real AES PDF encryption. Less polished than commercial alternatives but the privacy model is unmatched in scope.
- ✓ Image + PDF tools in one place
- ✓ Verifiable browser-only
- ✓ Real AES encryption
- ✓ Unlimited free
- ✕ Files >50 MB challenging
- ✕ Less polished than SmallPDF
- ✕ No native mobile app
Squoosh
squoosh.appBest for: Image compression with side-by-side compare
Made by Google's web platform team. Open-source, maintained well, single-image fine-tuning UX is excellent. The 'Made by Google' angle gives some users confidence in the privacy claim. Not a batch tool — one image at a time.
- ✓ Made by Google (audited)
- ✓ Open-source
- ✓ Best per-image compare slider
- ✕ Single-image only (no batch)
- ✕ No PDF tools
- ✕ No exact KB target
ImageOptim
imageoptim.comBest for: Mac users wanting batch image compression
macOS gold standard for image optimization. Fully offline, free, open-source. Drag a folder, walk away. Quality matches TinyPNG. The cost: Mac only.
- ✓ Completely offline
- ✓ Open-source
- ✓ Quality matches TinyPNG
- ✓ Free forever
- ✕ macOS only
- ✕ No PDF tools
- ✕ No fine-grained control
PDF24 desktop app
pdf24.orgBest for: Power users needing PDF tools without limits
25+ PDF tools in a free desktop application. No file size limits, no daily limits, no signup, no subscription. The web version uploads files; the desktop app runs entirely offline. Decline the bundled software offers during install.
- ✓ 25+ PDF tools offline
- ✓ No limits
- ✓ Free forever
- ✕ Dated UI
- ✕ Bundled software offers in installer
- ✕ Mac version less polished
PDFsam Basic
pdfsam.orgBest for: Open-source desktop PDF split/merge
Open-source desktop PDF tool focused on split, merge, rotate, extract. Doesn't try to be everything but excels at the core ops. Java-based (needs JRE). 15+ years of active maintenance.
- ✓ Open-source (Apache 2.0)
- ✓ Cross-platform
- ✓ Reliable for 15+ years
- ✕ Free tier excludes compress/OCR/convert
- ✕ Java requirement
- ✕ Functional UI
Caesium
saerasoft.com/caesiumBest for: Cross-platform offline image compression
Open-source desktop image compressor for Windows, Mac, Linux. Slider control, batch processing, preview window. Quality close to ImageOptim. The cross-platform option for users not on Mac.
- ✓ Cross-platform
- ✓ Open-source
- ✓ Batch processing
- ✕ Requires installation
- ✕ UI is utilitarian
- ✕ No PDF tools
Trimage
trimage.orgBest for: Linux users wanting drag-and-drop image compression
Linux-focused (Windows/Mac builds exist but rarely updated). Runs the standard PNG/JPG compression toolchain automatically. Drag a folder, click compress. Quality matches ImageOptim.
- ✓ Open-source
- ✓ Genuine offline
- ✓ Quality matches ImageOptim
- ✕ Linux primarily
- ✕ Bare-bones UI
- ✕ No fine-tuning
Stirling-PDF
github.com/Stirling-Tools/Stirling-PDFBest for: Developers/teams wanting Adobe-class PDF tools self-hosted
50+ PDF features rivaling Adobe Acrobat Pro. Open-source, self-hosted via Docker. Privacy comes from running on your own infrastructure. Not realistic for individuals — but excellent for IT teams and small organisations.
- ✓ 50+ features
- ✓ Open-source (15k+ stars)
- ✓ Self-hosted = full control
- ✕ Requires Docker / server
- ✕ Setup time
- ✕ Not for non-technical users
Drawboard PDF
drawboard.comBest for: Annotation-heavy PDF workflows
Microsoft Surface-favoured PDF tool. Their web Quick Tools claim browser-only processing for compress/merge/split. The full Drawboard PDF app is paid but excellent for annotation. Privacy claim is reasonable but less verifiable than open-source alternatives.
- ✓ Annotation-focused
- ✓ Surface integration
- ✓ Browser-based web tools
- ✕ Paid app for full features
- ✕ Less open than alternatives
- ✕ Limited tool variety
ExifCleaner
exifcleaner.comBest for: Removing image metadata before sharing
Niche but important — strips EXIF data (camera info, GPS coordinates, timestamps) from images before sharing. Open-source, offline, drag-and-drop. Most general image compressors don't strip GPS data; this tool's only job is to do that thoroughly.
- ✓ Open-source
- ✓ Offline
- ✓ Strips metadata thoroughly
- ✕ Single-purpose (only metadata)
- ✕ No compression
- ✕ No PDF support
Bulkresizephotos
bulkresizephotos.comBest for: Quick batch resize without upload
Browser-based batch resize tool. Privacy is genuine (verifiable via DevTools). Compression options are basic compared to ShrinkTo or Squoosh. Good for resize-only workflows.
- ✓ Browser-based
- ✓ Batch processing
- ✓ Free no signup
- ✕ Resize-focused (basic compress)
- ✕ No PDF tools
- ✕ Limited format support
PixelKnot / WhitelistedExifEdit (Mobile)
guardianproject.info / VariousBest for: Privacy-conscious mobile photo prep
Mobile alternatives that process photos on-device. Useful for users who only have a phone. Less powerful than browser/desktop alternatives but maintain the no-upload principle.
- ✓ On-device processing
- ✓ Mobile-native
- ✓ Privacy-focused
- ✕ Mobile only
- ✕ Less powerful than desktop
- ✕ Smaller user base
Frequently asked questions
Why does privacy matter for image / PDF tools?
How can I verify a tool is really browser-only?
Is browser-based really safer than 'we delete files in 2 hours'?
Are open-source tools always more private?
What about EXIF data and metadata leakage?
Does browser-based mean slower?
Can I use these tools offline?
- Tested in May 2026 against the workflow described in "How we tested"
- Free tier limits verified directly on each tool's pricing/limits page
- Privacy claims for server-based tools sourced from each provider's published privacy policy
- Browser-only privacy verified via Chrome DevTools Network tab
Last verified: January 2, 2026. Tools update their offerings frequently — verify current limits before committing to a workflow.
Skip the comparison — just try ShrinkTo
Image compression + 27 PDF tools, browser-based privacy, no daily limit, no signup. Free forever.
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