About this tool

Why it exists

Almost every “free” online PDF tool works the same way: you upload your document to a server, wait for a queue, then download the result. That is fine for a public brochure. It is uncomfortable for a signed contract, a payslip, a medical letter or a passport scan — files that people merge every day.

Modern browsers are capable enough to do the job locally. So this tool does exactly that: your PDF is opened, merged and saved on your own device. There is no upload step, because there is no server involved in the merge at all.

How it works

The page loads a small JavaScript engine called pdf-lib, which is self-hosted on this site. When you click merge, the engine reads each PDF, copies its page objects into a brand-new document and hands the result back to your browser as a download. Nothing is transmitted.

Because pages are copied rather than re-rendered, the merge is lossless: text stays selectable, fonts stay embedded, and images keep their original resolution. The optional A4 mode is the one exception — it deliberately scales pages onto a uniform canvas when you ask for it.

What we deliberately do not do

• No watermarks, no page limits, no daily quotas.
• No account, no email wall, no newsletter pop-up.
• No uploads, no file storage, no “your file will be deleted in one hour”.
• No selling of documents or metadata — there is nothing to sell.

How this tool is funded

The tool costs a one-time $9.99. That single payment covers hosting and the work of keeping the merger running as browsers change — it is not a subscription and there is no renewal. There is no advertising on the tool page, and your PDFs never reach an advertising system, because they never leave your device.

About klzth

klzth is a small, independent software studio, and Merge PDF Online is the first tool it ships. The name is abstract on purpose: it is a studio identity rather than a product name, which leaves the tools underneath free to keep plain, descriptive names. klzth is the name you will see on your receipt and in our policies.

The studio started from a specific irritation — that merging a PDF online so often means handing a private document to a server you know nothing about. Everything klzth builds is meant to avoid that trade: the work happens on your own device, the price is stated up front, and the limits are written down instead of hidden.

The plan is deliberately narrow. One unglamorous job done properly is worth more than ten half-finished utilities, so new tools only get added when they can meet the same bar: local processing, no watermark, no account, and a page that tells you plainly what the tool cannot do.

What is coming next

The same local-processing approach extends naturally to other everyday PDF jobs. On the roadmap: splitting a PDF into separate files, extracting a page range, rotating pages, removing pages and converting images to PDF. If you have a request, please get in touch.

Contact

Questions, bug reports and feature ideas are welcome — see the contact page. For details about privacy, read our privacy policy.