Protect PDF
Add an AES-128 password that is needed to open the PDF, with optional restrictions. Passwords are used in this browser tab and never uploaded.
- No file upload
- No sign-up
- No daily limit
This early version works with a limited set of PDFs up to 32 MB (25 MB on iPhone and iPad), including PDFs with an AES-128 password. Forms, comments, layers, attachments, newer compression and AES-256 aren't supported yet. Your original is never changed.
What's supported?
This version accepts PDF 1.x with complete classic cross-references, and stream lengths stored directly or, in unencrypted files, in a separate object. Files with later edits saved on top are accepted when they are unencrypted and every edit uses that classic form in a way this version has qualified; only their latest version is used, and earlier versions are checked but never copied. Object streams, cross-reference streams, hybrid files, other forms of later edits and PDF 2.0 are refused. Files with forms, layers, attachments or annotations other than links are refused until preservation is qualified, and so are bookmarks, links, tags and metadata streams in forms this version has not qualified. Inline images in forms this version has not qualified, pages that set default colour spaces, unsupported content encodings and incomplete inspection also cause a refusal. Encrypted input is limited to Standard R4 AES-128 with matching string and stream filters; AES-256 and other unqualified routing are refused. Passwords in this compatibility profile use single-byte characters and the first 32 bytes. Full rewrites create a new file identity. Unsupported inputs are not converted.
Files containing any of these are refused:
- digital signatures or signature fields
- XFA forms
- interactive form fields
- tags or marked content, in forms this version has not qualified
- document or object metadata streams, in forms this version has not qualified
- output intents (the colour profiles that PDF/A archival and PDF/X print files often carry)
- embedded files or file attachments
- associated-file relationships
- optional content layers
- page annotations, in forms this version has not qualified
- bookmarks, destinations or document navigation, in forms this version has not qualified
- custom page labels, in forms this version has not qualified
- document actions or multimedia, in forms this version has not qualified
- externally stored stream data
- document features outside the current supported profile
Drop PDFs here
or choose them from your device
Checking this device's limit…
Request-body observations · Observation unavailable
Request-body observation scope
Observed window APIs: none. Calls are counted since observation started. Measured sizes describe supported supplied bodies at the API call, before native conversion, including failed attempts; delivery is not measured. Multipart values are a lower bound, and streams or unmeasurable bodies have unknown sizes. Other APIs, workers, service workers, headers and earlier traffic are outside this counter. This is not a total network-byte count.
How to password-protect a PDF
- Drop one PDF onto the box above.
- Type the open password twice.
- Optionally, set a separate permissions (owner) password, then choose what people with only the open password may do — printing, copying, editing, commenting. Without a permissions password, no restrictions are added.
- Download the encrypted file.
The size limit is 32 MB per PDF (25 MB on iPhone and iPad), and the file selector shows the figure for your device.
This is AES-128, and we will not call it 256
This tool writes AES-128 in CBC mode using the standard PDF revision 4 security handler. The result panel reports the profile written by the engine. Ordinary strings and stream data are encrypted, and the complete output is checked before the download becomes available.
AES-128 is an explicit compatibility choice for this version's restricted PDF 1.x profile. AES-256 requires a separately qualified revision 6 handler and is not currently offered by this tool. Dependency defaults cannot change the selected algorithm.
Revision 4 is a legacy compatibility profile: the current PDF 2.0 specification deprecates older handlers and recommends revision 6. Choose software with qualified AES-256 support if you require that profile. The PDF specification's encryption guidance explains this distinction.
Use a long, unique password. This legacy profile accepts single-byte characters and uses only the first 32 bytes of the password. Files outside the declared input profile are refused without producing an output.
Restrictions are a request to PDF readers, not a lock. The printing, copying, editing and commenting restrictions are flags in the file that each PDF reader decides whether to apply; they are not enforced by cryptography. As of October 2026, Chrome and Edge apply only the printing and copying flags, and Firefox's built-in viewer ignores them by default. Restrictions need a separate owner password, which the tool calls the permissions password: without one, this tool adds no restrictions, because a file whose owner password equals its open password gives full rights to anyone who can open it. Even with an owner password, anyone with the open password can remove the restrictions, including with Verso's own Unlock. The open password is the part that genuinely keeps people out. We leave accessibility extraction permanently allowed regardless of your other choices, because switching it off blocks screen readers while stopping nobody.
Common questions
Can you recover my password if I forget it?
No, and that is a consequence of the design rather than a policy. Your file and your password are both handled entirely inside your browser — neither is ever sent to us, so there is nothing on our side to recover from. Write it down before you close the tab. The same goes for a permissions password: to change the restrictions later, unlock the file and protect it again.
Is the password sent anywhere to encrypt the file?
No. The encryption happens in a Web Worker on your machine. This is the practical argument for local processing: on an upload-based service your password and your plaintext file both arrive on someone else's server, which rather defeats the point of encrypting it.
What happens to fillable forms and bookmarks?
This version refuses files with form fields, bookmarks or page annotations before encryption. Tags, layers, attachments and metadata/profile streams are also outside the restricted page-content profile. Saving those features has not been qualified, and encryption cannot preserve PDF/A conformance. The page on why a PDF is refused explains each refusal reason.