How to Make a PDF Read Only (Free, No Acrobat)

"Read only" means four different things for a PDF, and each has a different fix. A password to open the file needs the [Protect PDF](/protect-pdf) tool. Form fields and comments that can no longer be changed need flattening with [Flatten PDF](/flatten-pdf). A permission flag that disables editing, printing or copying is an owner password, and PixelTools does not set one. A non-editable copy you simply send is the fourth option: a flattened or image-based file, covered below. Decide first what you are protecting against. Stopping a stranger from opening the file is a password job. Stopping a client from altering a filled-in form is a flattening job. Stopping a determined person from editing text is not something a PDF can fully promise, as the sections below explain.

Use [Protect PDF](/protect-pdf): drop in the file, type a password twice, and download the locked copy. The password is applied as AES-256 encryption, and the tool reads the result back and refuses to give you a file that is not really AES-256, so a failed lock never produces a silently unprotected download. Everything runs in your browser, so neither the file nor the password is uploaded. Be clear about what this is: an open password, not a read-only flag. Anyone who has the password can open the file, and the tool does not set print, copy or edit restrictions. The password cannot be recovered if you lose it, so keep an unprotected original. If the file already has a password, the tool says so and asks you to remove it with [Unlock PDF](/unlock-pdf) first.

Flattening is the closest thing to genuinely read only for a completed document. [Flatten PDF](/flatten-pdf) offers two modes. Form mode draws each field's current value onto the page and removes the form layer, so the file stays lossless and its text stays selectable. Whole-document mode redraws every page as an image, which also bakes in comments, highlights and signature stamps. The trade is real: text can no longer be selected or searched and the file usually grows. If the tool finds no fields and no visible annotations it tells you there is nothing to flatten instead of returning an identical file. For a full walkthrough see [how to flatten a PDF](/blog/how-to-flatten-a-pdf), and fill the form first with [how to fill out a PDF form online](/blog/fill-out-pdf-form-online).

An owner password sets permission flags on a PDF, such as no printing, no copying text and no editing. The file still opens with no prompt, which is why it is not the same as an open password. These flags are advisory: a viewer chooses whether to honour them, and the [Unlock PDF](/unlock-pdf) tool can write out a copy without them when you leave the password box blank, as explained in [how to remove a password from a PDF](/blog/how-to-remove-password-from-a-pdf). PixelTools Protect PDF deliberately sets only an open password and its own FAQ says print and copy restrictions are not real protection. If you need those flags specifically, use a desktop PDF editor that exposes them, and treat them as a deterrent for honest users, not security.

For most everyday cases, send a flattened copy. Fill in the form, add your signature with [Sign PDF](/sign-pdf), then flatten with whole-document mode so the signature and every entry become part of the page. The recipient sees the finished document and cannot click into fields or drag the signature away. Order matters: flatten after signing, never before. This is how to make a PDF read only for an invoice, a completed application or a signed agreement. Keep your editable original under a different name, because flattening is one-way. If the recipient also needs to be unable to open it without your say, add an open password afterwards with Protect PDF. See [how to sign a PDF](/blog/how-to-sign-a-pdf) for the signing step.

Open the finished file in a different viewer from the one you made it in and test it. For a flattened file, click where the form fields were, try to select a signature, and search for a word you know is on the page. In form mode text should still be found; in whole-document mode search finds nothing, which is expected. For a password-protected file, confirm the prompt appears and your password works before you email it, and share the password through a different channel from the file. If you need the text back after a whole-document flatten, run [OCR PDF](/ocr-pdf) on the copy, covered in [how to OCR a PDF](/blog/how-to-ocr-a-pdf). If sensitive content must be gone rather than locked, redaction is the right job, not protection: see [how to permanently redact a PDF](/blog/how-to-permanently-redact-a-pdf).