1Your documents
2Watermark text
Add the recipient: “…, Martin Agency”.
Appearance
Typeface
Colour
File password
AES-256 (PDF 2.0): quantum-resistant, and opened by current phones and computers. The preview stays visible; only the download is protected. An image is delivered as an encrypted PDF.
3Review, then download
Drop a document to get started.
How it works
- 1
Drop your document
A PDF or a photo, even one taken on an iPhone. Several at once if you need.
- 2
Say what it's for
For example “Rental application, Martin Lettings, 11/10/2026”. Ready-made templates are included.
- 3
Check, then download
The preview shows exactly what you'll get. The watermarked file is saved to your device.
Your documents never leave your device
Most watermark websites upload your ID to their servers. Cachety doesn't: all the work is done by your browser, on your own phone or computer.
Processed on your device
Your files stay in your device's memory. Close the tab and everything is gone.
Blocked by design
The page forbids your browser from sending data to any other website. Even if something went wrong, your files couldn't leave.
No account, no tracking
No sign-up, no tracking cookies, no visitor analytics, no ad networks.
Open source and verifiable
The code is public. Anyone can read it, check it, or host their own copy of the site.
Check it yourself: the airplane-mode test
Open this page, then switch off the internet (airplane mode). Drop in a document: Cachety still works. Proof that nothing goes over the internet.
Everything you need to protect a copy
Watermark across the page
Repeated diagonally and blended into the image: it can't be deleted by simply editing the PDF.
Black out information
Hide an account number, a tax reference or a photo. The content is really removed, not just covered.
Traceable copies
A date and a unique reference on every copy: if one turns up somewhere, you'll know where it came from.
One version per recipient
A personalised version for each agent or bank, in a single download.
Password
Lock the PDF with strong AES-256 encryption, the standard banks use.
Hidden data removed
Selectable text, metadata and the GPS location of photos are stripped from the final file.
Maximum file size
1, 2, 5 or 10 MB per file, for websites that limit upload sizes.
Works on your phone
iPhone and Android, HEIC photos included. Add Cachety to your home screen like an app.
Free, open source, made in France
Cachety is free, open-source software (AGPL licence). Its code is open to everyone and will stay that way. It builds on Filigrane Local and Filigraneur, two open-source French projects.
Designed and maintained by Amir Moradi · GitHub
Support Cachety
Cachety is free and will stay free. But it takes time, and the domain name and development tools cost money. If Cachety helped you, a small donation keeps it going.
Make a donationOptional. Payment happens on GitHub Sponsors, outside this site.
Frequently asked questions
Are my files uploaded to a server?
No, never. The site doesn't even have a server that could receive a file. Your browser does all the work, and the page technically forbids it from contacting any other website. The airplane-mode test proves it in ten seconds.
Is it really free? What's the catch?
There isn't one: no account, no paid version, no data collected. Because nothing is processed on a server, hosting the site costs almost nothing, and the open-source code guarantees it stays free. To fund its development, Cachety relies on optional donations, and may one day show a few hand-picked sponsored links (encryption tools, open-source software…). Never ads that track you, and never anything based on your documents.
Which files can I watermark?
PDFs and images: JPG, PNG, iPhone photos (HEIC), WebP, GIF, BMP and AVIF. Up to 200 MB per file and 500 pages per PDF, several files at once.
Can the watermark be removed?
Not by editing the PDF: the watermark is part of the image of each page. To be honest, nothing stops someone photographing or retouching a document. A watermark discourages reuse and lets you trace where a leak came from.
What should I write in the watermark?
Three things: what the copy is for, who you're sending it to, and the date. For example “Rental application, Martin Lettings, 11/10/2026”.
Does it work on my phone?
Yes, on iPhone and Android. Open cachety.com in your browser, tap the drop area and pick a photo or a PDF. You can also add Cachety to your home screen.
Practical guides
Step-by-step help for everyday situations.
- How to watermark your ID and documents for a letting agent or landlordRenting a flat? Watermark your passport, payslips and bank statements for a letting agent in a minute, free, without uploading them anywhere.
- How to watermark a copy of your passport or driving licence before emailing itWatermark a copy of your passport or driving licence before you email it. Free, no account, and your photo never leaves your phone or computer.
- How to send bank statements and payslips safelyNeed to send bank statements or payslips? Learn what to watermark and what to black out, like account numbers, before you hit send. Free and private.
- How to properly redact a PDF or image for freeRedact a PDF for free and make sure hidden text is really gone. Why black boxes often fail, and how to black out details safely in your browser.
- How to watermark documents on an iPhone or Android phoneWatermark documents and photos on your iPhone or Android phone, free and without an app store download. HEIC photos supported, nothing uploaded.
- How to password-protect a PDF for free, without uploading itPassword-protect a PDF for free, right in your browser. Strong encryption, a one-click password generator, and your file is never uploaded.