ByteScope

Sign PDF

Open a PDF, fill its fields, drop your signature where it belongs — drawn, typed or photographed — and download. Signed in this tab, nothing uploaded.

Your files never leave your browser — all processing is local.

Drop a PDF here

or click to browse — opened in this tab, nothing uploaded

Limits — read these before you sign

  • This is a visual signature (your signature drawn onto the page), not a digital signature. It can't prove the document wasn't changed after signing, and it can't prove that you are the one who signed. If a document needs legal force or a certificate-based signature, use the signing method the other party asks for.
  • If the PDF already carries a digital signature, adding anything to it makes that signature invalid. When the file opens and a signature field is found, you are warned first.
  • XFA forms (some older government and insurance forms) can't be filled in — you can only place text on top of the page.
  • Encrypted PDFs and PDFs with permission restrictions can't be opened.
  • With “keep fillable fields”, Chinese or Japanese field values are drawn by the PDF reader, so they may look different in different readers. To get the same look everywhere, download flattened.
  • Your file is not uploaded.

About this tool

A lease the landlord sent over that needs a signature and a date before it goes back; the company's expense claim or application form that is a fillable PDF; a school consent form that would otherwise be printed, signed and scanned again. This page opens the PDF, shows every page, lets you fill the form fields it finds and place your signature, text, today's date, check marks or initials anywhere on any page, and then downloads the result. Pages are drawn one at a time as you scroll, so a hundred-page document stays usable, and the layout works at phone width because signing on a phone is half the point.

Three ways to make a signature

Draw it with a mouse, a finger or a stylus — a pen reports pressure, so strokes get thicker where you press harder. A drawn signature is written into the PDF as vector paths, so it stays sharp at any zoom. Type it instead and pick one of three handwriting-style fonts (Caveat, Dancing Script and Great Vibes, all under the SIL Open Font License); a typed signature is rendered to an image at four times the placed size before it goes in. Or photograph the signature you already put on paper: the page lifts the ink off the paper, turns the background transparent and crops to the strokes, so the PNG lands cleanly on the document. Every signature can be moved, resized (keeping its proportions) and deleted before you download. If you tick "remember on this device", the signature is saved in this browser's IndexedDB and offered again next time; the box is off by default, and a "delete remembered signature" button clears it.

Form fields: flatten, or keep them fillable

If the PDF has an AcroForm — text boxes, check boxes, radio buttons, drop-downs — the fields are detected and shown as inputs right on the page, so you type into them where they sit. There are two download buttons. "Flattened" writes the field values and everything you placed into the page content itself, so the recipient sees exactly what you see and cannot edit it. "Keep fillable" writes only the values and leaves the fields live, for forms someone else still has to fill. One caveat with the second mode: when a field holds Chinese, Japanese or other characters outside the basic Latin set, the PDF stores only the value and leaves drawing it to whichever reader opens the file, so that text may look different in Acrobat, Chrome and Preview. If it has to look the same everywhere, choose flattened — this page then draws the text into the page itself. XFA forms (older forms from some governments and insurers) cannot be filled natively; you can still lay text on top of the page, and on export the /XFA entry is removed so readers show the plain form plus what you added instead of the old XFA content.

A visual signature is not a digital signature

What this page adds is a visual signature — a picture of your signature drawn onto the page. It is not a digital signature. It cannot prove that the document has not been changed since it was signed, and it cannot prove that you were the one who signed it. If a document needs legal effect or a certificate-based signature, use the signing method the other party specifies. The reverse also holds: if the PDF already carries a digital signature, adding anything to it — a signature, a date, a single filled field — invalidates that signature, which is true of every PDF editor and not a fault of this one. The page checks for signature fields when the file is opened and warns you before you change anything.

Encrypted PDFs and PDFs with permission restrictions cannot be opened here; this page does not ask for, guess or remove passwords — unlock the file in the program that locked it and come back. Everything else happens in this tab: the file is read with the File API, the pages are drawn and the signed PDF is assembled in JavaScript, and the download is built in memory. There is no server behind the page, so the document is never uploaded. Need to attach the signed pages to something else, send only some of them, or check what the file says about itself? Merge PDF, Split PDF and Remove PDF Metadata are built the same way.

Frequently asked questions

Is a signature made here legally binding? Is it a digital signature?

It is not a digital signature. The page draws your signature onto the page as graphics — it adds no certificate, no cryptographic hash and no timestamp — so it cannot prove the document was not altered afterwards and cannot prove who signed it. Whether a visual signature is enough is for the document and the other party to decide; anything that requires legal effect or a certificate-based signature must be signed the way the other party specifies. The page says this on screen so nobody downloads a file assuming otherwise.

Is my PDF uploaded anywhere?

No. The file is opened with the File API, the pages are drawn by a PDF renderer running in this tab, and the signed PDF is assembled in JavaScript and offered as a download the browser built in memory. There is no API behind this page, so the document has nowhere to go. The only thing that is ever stored is the signature itself, and only if you tick "remember on this device" — it then lives in this browser's IndexedDB, not on a server.

Can I fill in the form fields, not just sign?

Yes, if the PDF has an AcroForm. Text boxes, check boxes, radio buttons and drop-downs are detected and shown as inputs on top of the page; read-only fields are left alone. Download "flattened" to bake the values into the page, or "keep fillable" to leave the fields live for the next person. XFA forms — older forms from some governments and insurers — cannot be filled natively, because their fields are defined in an XML layer this page does not read. You can still place text on top of the page, and the exported file has the /XFA entry removed so readers show the ordinary form and what you added instead of the old XFA content.

Can I sign on my phone or tablet?

Yes — that is one of the main cases this page is built for. The signature pad uses Pointer Events, so a finger, a stylus or a mouse all work, and a stylus that reports pressure makes thicker strokes where you press harder. The pad stretches to the full width of the screen at 375px, and the toolbar wraps instead of overflowing. On a phone the photo option can open the camera directly, so you can also sign on paper and photograph it.

Where is a remembered signature stored, and how do I delete it?

Nowhere, unless you ask. The "remember on this device" box is off by default. When you tick it, the signature is saved in this browser's IndexedDB under the database bytescope-pdf-sign — on this device, in this browser profile, not synced anywhere and never sent to a server. The "delete remembered signature" button on the page removes it, and clearing this site's data in the browser removes it too.

I filled a field in Chinese and it looks different in another PDF reader. Why?

Because you downloaded with "keep fillable". In that mode the PDF stores the value of a field but not a drawing of it for characters outside the basic Latin set, so each reader generates the appearance itself with its own fonts and spacing — Acrobat, Chrome and Preview will not look identical. If the text has to look the same everywhere, download "flattened": this page then draws the text into the page content itself, and every reader shows the same pixels.

The PDF already has a digital signature, or a password. What happens?

A digital signature is detected when the file is opened and you get a warning first: adding anything — a signature, a date, one filled field — changes the bytes the signature covers, so it will no longer verify in any reader. If that signature has to stay valid, do not modify the file; use the signing flow the other signer expects. A password-protected or permission-restricted PDF cannot be opened here at all; this page does not try to open, guess or strip passwords. Remove the password in the program that set it and open the unlocked file.

Related tools