Protect PDF — Add Password to PDF
Add password protection to a PDF file.
Drop your PDF file hereTap to select a file
Supports PDF, up to 200MB
What to do next
Related tools
About Protect PDF
Protect PDF is the kind of utility you bookmark and reach for when you need it. Add password protection to a PDF file. It loads quickly, works on any modern browser, and produces a result you can download or copy in a single click.
Protect PDF sees the most use from freelancers sharing scanned receipts and researchers archiving reference papers, but the design is intentionally generic enough that you do not need a specialist background to get a good result. The defaults aim at the most common case so a first-time user can get the right output without changing any settings.
The right moment to reach for Protect PDF is when you have a focused PDF document workflow job that fits inside a browser tab. Open the page, drop in the file or paste your input, choose the options that matter, and the tool returns the result.
Protect PDF runs on the open-source pdf-lib JavaScript library — an open-source, well-audited engine that performs the PDF document workflow natively in the browser. It accepts PDF and produces output that opens in any standard PDF viewer. Per-run input is capped at 200 MB.
Protect PDF is structured so the question "where is my file processed?" has a single answer: in your browser tab. The engine, the controls, and the result panel are all on one page. Navigating away or closing the tab clears the page's memory the way it does for every other tab.
For multi-step jobs, Protect PDF sits next to Remove PDF Password, Compress PDF, and Watermark PDF. None of them depend on each other — you can use Protect PDF on its own — but together they cover the common variations of the task this page exists to handle.
The only practical limit is the 200 MB per-file ceiling, which keeps the tool responsive across a wide range of devices. Run the tool ten times in a row, run it ten thousand times — it behaves the same way and produces the same quality of result.
The transformation in Protect PDF is deterministic — the same input plus the same options produces the same result every run. That predictability matters when the result has to match an upstream specification or be reproducible later.
When the job finishes, Protect PDF hands you the result as `{name}-protected.pdf`. Filenames are derived from your input where possible, so a quick batch of jobs leaves you with a tidy folder rather than a pile of generic "output (3)" files. Nothing is auto-saved on Favtoo's side because nothing was ever sent there.
From a product perspective, Protect PDF is one of the simplest possible expressions of "do one thing well." The catalog contains dozens of related tools that each handle a slightly different PDF document workflow task, and every one is a separate page rather than a tab inside a larger app. That separation keeps each tool fast to load and easy to bookmark.
Protect PDF runs as a regular web page, so there is no install step or permission grant before the first run. The page can be audited by viewing the source or by watching the developer-tools Network tab while a job runs.
Pro tip: Protect PDF works just as well in a private/incognito window as in a normal one, which is occasionally useful when you want zero browser-history footprint of the job. Another tip: if the tool ever feels slow, it is almost always because the browser tab is competing for CPU with another tab — pausing or closing the heavy ones gives the engine room to work.
For most failure modes, refreshing the page and re-running the job is enough — the engine has no persistent state to corrupt. If the same input fails twice in a row, the input itself is most likely the problem (a truncated file, an unexpected variant of the format, or a stream the engine does not recognise).
That is the whole tool. Use Protect PDF for as long as it stays useful to you, and if it does, the catalog has many more tools built the same way. Each applies the same single-purpose discipline, so the way you used this page transfers to the next one you try.
How it works
- 1Open Protect PDF in your browser. The page loads quickly and the tool is ready to use the moment it becomes interactive.
- 2Select the PDF file you want to process — drag-and-drop and the file picker both work.
- 3Tweak the controls if the defaults are not quite right for your input. The options are kept short and labelled in plain language.
- 4Click to start the job. The engine (the open-source pdf-lib JavaScript library) processes the input in the page; you can watch the progress indicator until it completes.
- 5Download the result as `{name}-protected.pdf`. The file is generated in your browser and saved through your normal download flow.
- 6Run additional jobs as needed. The same controls and defaults apply on every run.
Common use cases
- Convert a bundle of forms into a single archival PDF using Protect PDF.
- Combine a portfolio sample into a single application packet.
- Shrink a scanned report so it fits past an email gateway.
- Send a polished, print-ready PDF to a client without watermarks.
- Add page numbers to a draft report before circulating it for review.
- Strip blank or test pages from a scanned document.
- Lock a confidential document with a password before sharing externally.
- Prepare a packet of receipts for an expense report submission.
FAQ
How strong is the encryption?
PDFs are protected with AES-256 encryption, the industry standard for document security.
Can I set different user and owner passwords?
Yes — set a user password to open the file and an owner password for editing permissions.
What if I forget the password?
There is no recovery option. Make sure to save your password somewhere safe.
What does Protect PDF do that command-line tools do not?
Desktop apps usually have more advanced features but require installation, maintenance and (often) a licence. Paid online tools are convenient but route your file through their servers and gate downloads behind accounts. Protect PDF sits in between: free, instant, and private, but intentionally narrow in scope. For one-off jobs and the common PDF document workflow operations, it is usually the lowest-friction choice; for highly specialised work, a dedicated app is still the right answer.
Do I need to install anything to use Protect PDF?
No installation is needed. Protect PDF runs as a normal web page, with no browser extension, no native helper, and no separate desktop client to download. That is partly a privacy choice — extensions can request broad permissions, while a regular page is sandboxed by default — and partly a convenience one: you can use Protect PDF on any computer you have temporary access to without leaving anything installed on it.
Why does Protect PDF feel slow on large inputs?
Most jobs finish in seconds. Speed scales with input size and with how many CPU cycles your browser tab has available — the engine runs in your browser, so it shares resources with whatever else you have open. For inputs near the 200 MB ceiling, expect anywhere from a few seconds to roughly a minute on a typical laptop. Closing other heavy tabs noticeably speeds things up.
Does Protect PDF ask for any browser permissions?
Protect PDF only needs the standard web platform — file picker access for the inputs you choose to load, and optionally clipboard access if you copy the result rather than downloading it. There is no microphone, camera, geolocation or background-permission request, because none of those are needed for the work the tool does.
Can I process multiple files at once with Protect PDF?
Protect PDF processes one input at a time by design — it keeps memory usage predictable on lower-end devices and makes results easier to verify. To handle a folder, run the tool once per file; the page stays loaded between runs and remembers your last-used settings, so the second run is essentially instant.
Why did Protect PDF reject my input?
Failures usually fall into one of three buckets: the input is in an unsupported format, the input is over the size cap, or the input is structurally malformed (a truncated download, a partial export, or a stream the engine does not recognise). The first two are easy to confirm — check that your file is one of PDF and that it is below 200 MB. For the third, opening the file in its native viewer first is the fastest way to confirm the source is intact.
Does Protect PDF need an internet connection to run?
Once the page is loaded, Protect PDF can complete jobs without an active internet connection — the engine is bundled with the page, so there is no per-job network call. The initial page load does require a connection (to fetch the static assets), but after that you can disconnect entirely and the tool will still work. This is a side-effect of the local-first architecture, not a deliberate "offline mode" feature.
Will Protect PDF keep working in a year?
Protect PDF is updated whenever the underlying engine releases an improvement or a bug fix. Because the tool is delivered as a static page, every visit fetches the latest version automatically — there is no "version" to manage on your end. If a particular release ever changes default behaviour, the change is documented on Favtoo's changelog so you can confirm what shifted.