Alternatively:

    gs -dBATCH -dNOPAUSE -q -sDEVICE=pdfwrite -sOutputFile=output.pdf input1.pdf input2.pdf input3.pdf [...]

I use something similar on linux pdfunite input1.pdf input2.pdf output.pdf

or pdftk

Seems like it's not working without the internet connection. I wanted to be sure that PDFs are not uploaded and disconnected network just before selecting them. The error in the console was:

GET https://pdfwrench.com/_nuxt/pdf.worker.498fee0.worker.js net::ERR_INTERNET_DISCONNECTED

Why make an account on a website when this is something you should be able to do locally? This is a perfect use case for a CLI tool.

https://github.com/stlehmann/pdftools

No uploads, open source so fewer privacy concerns, just a simple python package.

Disclosure: this is an open source project I've contributed to recently.

First class PDF merge and split is built into OSX Preview app.

Just show thumbnails, drag them around including between windows, then to merge, select all pages and drag to folder.

Firefox not supported.

It in fact screams at me to "update" my browser "to the lates [sic] version" of Chrone, Brave, and Opera in an alarming red banner:

Sorry, your Browser does not support the latest features we use. Our Application was tested on the following Browsers: Chrome, Brave and Opera. Please, update your browser to the lates version of one of supported browsers.

I'll just stick to the CLI commands I managed to cobble together for the same purpose. I've even managed to get OCR down with Tesseract[0]

Photo: https://imgur.com/a/wrqUs93 [0]: Tesseract: https://github.com/tesseract-ocr/tesseract

Anything for password protecting PDFs without any file upload?

qpdf: http://qpdf.sourceforge.net/

It has other neat features too (like stripping print/edit restrictions).

So it's javascript? The website does not say.

pdfjam is my goto for stuff like this. It’s a suite of commandline tools for editing pdfs.

Merging is done with pdfjoin. I also often use pdf90 to rotate.