Sign PDF
Put your signature on a page without anything happening to the rest of the document. Your file is appended to, never rebuilt, so the text in the contract you sign is still text when you send it back.
Drop the PDF in, put your signature on the page, save it.
Free · no sign-up · nothing uploaded. Your PDF is opened and signed on your own machine, so there is no page limit, no size cap and no queue. The file you save is the file you dropped in with a signature appended, byte for byte, so the text in it is still text.
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How to sign a PDF
Drop your PDF in
Any size, any number of pages. It is opened in the tab with a renderer served from this domain, so nothing is uploaded and there is no queue to wait in.
Make your signature and put it on the page
Draw it, type it in one of five faces, or upload a photo and let the paper be removed. Then click the page to place it, drag it where it goes, and pull a corner to resize.
Read the rail, then save
The rail says how many bytes were added, whether the original bytes survived and whether the text is still text. Then the file is written on your own machine.
Every other signer hands you back a different file
Before this tool was built, the results ranking for "sign pdf" were each given the same two page agreement: a 1,966 byte PDF with 861 characters of real text on it. Then the files they gave back were opened and read. The difference is not cosmetic.
| Signer | Your file | Size after | Original bytes | Text after |
|---|---|---|---|---|
| floi | stays in the tab | 6,237 B (+4,271) | all there, byte for byte | selectable |
| iLovePDF | uploaded | 45,410 B (+43,444) | none, file rewritten | selectable |
| Smallpdf | uploaded | not measured, see below | ||
| Signeasy | asks for an email first | not measured, see below | ||
| Adobe Acrobat online | uploaded | sign-in wall | ||
Two of those rows say "not measured" and they stay that way. On Smallpdf the signature was made and placed on the page, but the file that came back had no signature in it, and there is no way to be sure that is the tool rather than an artefact of driving it automatically, so nothing is claimed. Signeasy asks for an email address before it will sign anything, on a page whose title tag reads "No Signup, No Watermarks", and no address was given. Both are checkable in a minute if you want to check them.
The row that matters is the second one. iLovePDF does keep your text, which several signers do not, and it deserves the credit for that. But the file it returns is a new file: 23 times the size, produced by a different engine, with none of your original bytes anywhere in it. For a contract that is a meaningful difference, because the document you send back is no longer, at the level of the bytes, the document you were sent.
What "appended" means, and why it is the whole design
PDF has always allowed a file to be extended by writing to the end of it. The format calls this an incremental update, and it is how a reader saves a comment on a document without rewriting the document. This tool does nothing else.
| What is added | Why |
|---|---|
| An image object | The ink. One colour plane, which compresses to almost nothing, plus a transparency mask that carries the shape of the strokes. |
| A content stream | One matrix and one draw instruction per signature. A few dozen bytes. |
| Two bracket streams | A q and a Q, wrapped around whatever the page already drew, so an unbalanced graphics state in your document cannot bleed into the signature. |
| A replacement page | The same page dictionary with the signature added to its resources. The old one stays in the file and is simply no longer pointed at. |
Everything else in your PDF is the identical run of bytes it arrived as. That is checkable with any tool that compares two files: the signed version starts with the whole of the original.
Using the PDF signer
Three numbered steps run along the panel, because the middle one is the step every rival leaves you to work out. What follows is every control on screen and when you would touch it.
The stage, and the page on it
The empty stage is the drop target rather than a caption above one, so a PDF can be dropped anywhere on it or clicked to open a file picker. Once a document is open the page is fitted into a fixed-height stage, so turning to a landscape page never moves the control you were about to press.
| Control | What it does |
|---|---|
| Arrows either side of the page count | Move a page at a time. Only shown on a document with more than one page. |
| The numbered row along the bottom | Jumps to any page. A page carrying a signature gets a green dot, so a long document can be checked at a glance. |
| Duplicate | Copies the selected signature slightly offset from itself. Appears only when one is selected. |
| Remove | Takes the selected signature off. Delete and Backspace do the same. |
| Full screen | Moves the panel into the whole viewport. The same panel is moved, never copied, so there is only ever one document. |
Making a signature
Create your signature opens a dialog with three tabs. Whichever you use, the ink colour along the bottom applies to all three, and the result lands in a tray beside the button so a second and third signature cost one click each.
Draw
A ruled pad, like a cheque. The stroke thins as the pen moves faster, which is the one thing that makes a mouse-drawn name look like a name rather than a scribble, and it is why drawing with a finger or a stylus comes out better than with a mouse. Undo removes the last stroke; Clear removes them all.
Type
Your name in four handwriting faces and one plain one. Today's date fills in today in your locale's long format and switches to the plain face. Initials shortens whatever is in the box to
A. M.Upload
A photo or scan of a signature on paper. The paper is removed automatically: the darkness of each pixel becomes its opacity, so the soft edge of a real pen stroke survives instead of being cut into a staircase. Paper removal is the threshold. Slide it left if ink is disappearing, right if paper is still showing.
The three tabs do not cost the same. Almost all of a signature's weight is the transparency mask that carries the shape of the strokes, so the cost follows how much of the box has ink in it and how finely the edges are shaded. Measured on 4 September 2026, signing the same 1,966 byte agreement with the same name:
| Made with | Ink size | Added to the PDF |
|---|---|---|
| Draw | 258 x 114 | 4.3 KB |
| Upload a photo | 900 x 166 | 9.6 KB |
| Type | 522 x 99 | 17 KB |
Typing costs the most because a handwriting face lays fine, evenly shaded strokes across the whole box, and that is the hardest thing for the mask to compress. A drawn name is cheapest because most of its box is empty. None of the three is large enough to matter next to the document, which is the point of appending rather than rebuilding.
Putting it on the page
A new signature is placed for you as soon as it is made, because being handed a signature and no way to use it is where people give up. After that the page has a dashed outline for as long as there is something to place, and clicking anywhere on it adds another.
| Gesture | What it does |
|---|---|
| Drag the signature | Moves it. It cannot be dragged off the page. |
| Drag a corner handle | Resizes it. The aspect ratio is held on every corner, because a stretched signature is a forged one. Size follows the corner you are pulling, so a short wide signature takes its width from sideways travel rather than leaping on a small vertical one. |
| The x above a selected signature | Removes that one signature and leaves the rest. There is a bin in the header that does the same thing. |
| ← → ↑ ↓ | Nudges the selected signature by half a percent of the page. |
| Shift and an arrow | Moves it ten times as far. |
| Delete or Backspace | Removes the selected signature. |
| Esc | Leaves full screen, or closes the signature dialog. |
| Signature size | Sets the width in PDF points for the next placement, and resizes the selected one about its centre, so the thing you are aiming at stays put. Selecting a signature moves the slider to that signature's own width. 180 points is about 63 mm, which is a normal signature on a letter. |
Reading the rail before you save
The rail is the argument, so it quotes the file rather than an estimate of it. The document is genuinely rebuilt on every change and the number shown is the length of the bytes that the save button is about to hand you.
| Row | What it is telling you |
|---|---|
| Original bytes untouched | The whole of your file is still in there, in order, unchanged. This is the row no other signer prints. |
| Text is still text | Nothing was flattened, so the contract can still be searched, copied from and read aloud. |
| Pages were rebuilt as images | The warning version of the two rows above. It appears only when the append could not be done, and the reason is on the same line. |
| The byte count | How much was added, against the size of the file you dropped in. |
What this tool will not do
Four limits, and each one is a deliberate refusal rather than a gap.
| Not this | Why, and what to do instead |
|---|---|
| A cryptographic digital signature | That needs a certificate issued to you by an authority, and a private key that a web page has no business holding. What this makes is an electronic signature, which is the same thing every free online signer makes. The difference is set out in the guide. |
| An encrypted PDF | Nothing can be appended to a file whose every stream is enciphered. Save a copy without the password and sign that. |
| Sending it to someone else to sign | That is a service with accounts, email and an audit trail, and it cannot be done without a server. This signs a document you already have. |
| Filling in interactive form fields | Text can be typed and placed anywhere, which covers most fill-and-sign work, but real AcroForm fields are not detected. Use a reader that understands them. |
A signature made here, or on any free online signer, is a picture of your name on a page. In most of the world that is a valid electronic signature for ordinary agreements, and it is not the same thing as a digital signature a reader can verify. Which one you need, and how to tell them apart, is the whole of the guide below.
Frequently asked questions
Is my PDF uploaded anywhere?
No, and this is the one claim on the page that is worth checking rather than believing. Open your browser's network panel, drop a contract in, sign it and save it: there is no request carrying your file, because there is nowhere for it to go. The PDF is read into the tab with FileReader, drawn with a renderer served from this domain, and written back out by JavaScript running on your own machine. The only fetches are the renderer itself and its fallback fonts, both from floi.dev, both cached after the first page you sign, and both sent before you have chosen a file. It is also why there is no page limit, no size cap, no queue and no sign-up: none of those are generosity, they are just what is left when there is no server to protect.
What actually happens to my file when I sign it here?
Nothing is rewritten. A PDF is allowed to be extended by appending to the end of it, which the format calls an incremental update, and that is what this does. Your file is copied out byte for byte and a short section is added after it holding the signature image, one content stream that draws it, and a replacement page dictionary pointing at both. Measured on 4 September 2026 across ten real PDFs from 1,966 bytes to 2.1 MB, versions 1.4 to 1.7, with both cross reference tables and cross reference streams: every one came back with the original bytes intact as the first bytes of the file, and every one gained between 4,256 and 4,668 bytes, a spread of 412 bytes across a range of file sizes that differs by a factor of a thousand. The cost of signing does not scale with the document, because the document is not touched.
Will the text still be selectable and searchable afterwards?
Yes, because nothing was flattened. Signing here adds a picture to the page rather than turning the page into a picture, so every character in your contract is still a character. On the same ten test files the extracted text was identical before and after, to the character, and exactly one image had been added. This matters more than it sounds: a rebuilt PDF cannot be searched, cannot be read aloud by a screen reader, cannot be copied from, and gets much bigger. There is one exception, and the panel names it before you save. If a file is encrypted or its index cannot be followed, the pages are rendered and rebuilt as images instead, and the rail says Text is no longer selectable in those words.
Can I sign a password protected PDF?
Not directly, and the tool refuses rather than guessing. Every string and stream in an encrypted PDF is enciphered, so writing plain objects beside them would make a file no reader will open. If the password is one you know, open the file in Preview on a Mac or any reader on Windows, save a copy without the password, and sign that. If the document arrived locked from someone else, they have to send it unlocked. A tool that claimed to sign it would either be storing your password or quietly rebuilding the file as pictures.
Can I put a signature on every page, or more than one on a page?
Yes to both, with no limit on either. A signature you have made stays in the tray, so putting it on page eleven is: go to page eleven, click the page. The same signature can go on a page as many times as you like, and Duplicate above the stage copies the selected one where it stands. Several different signatures are fine too, which is the case where two people are signing the same agreement on the same machine. Every placement is a separate item you can drag, resize with a corner, nudge with the arrow keys or delete.
Can I add the date or my initials as well as a signature?
Yes, through the same Type tab. It has a plain typeface alongside the four handwriting ones, because a date set in copperplate looks wrong, and two shortcuts: Today's date fills in today in your own locale's long format, and Initials shortens whatever name is in the box to A. M. Each one becomes its own item in the tray, so a name, a set of initials and a date can all sit on the page at once and each be moved on its own. What this is not is a form filler: there is no detection of form fields, and if your PDF has real interactive fields you should fill those in a reader that understands them.
Which of the three ways of making a signature gives the smallest file?
Drawing it. Signing the same 1,966 byte agreement with the same name on 4 September 2026 added 4.3 KB drawn, 9.6 KB from a photo and 17 KB typed. The order surprises people, so here is the reason. Almost all of a signature is the transparency mask that carries the shape of the strokes, and a mask compresses well when most of it is empty or flat. A drawn name leaves most of its box untouched. A handwriting face lays fine, evenly shaded strokes right across the box, which is the worst case. A photo sits in between, and the Paper removal slider improves it further by flattening the faint background grain to fully transparent. None of the three is big enough to matter next to the document itself.
Does it work on a phone or a tablet?
Yes, and drawing is genuinely better there than on a desktop, because a finger or a stylus gives the stroke real velocity and the pad varies the line width with it. The layout collapses to one column below 900px, with the page above the rail. The one thing worth knowing on a phone is that a very large PDF is held entirely in the tab's memory, so a 200 MB scan is a lot to ask of a five-year-old handset in a way it is not of a laptop.
Is there a watermark, or a limit on how many documents I can sign?
No watermark, and no limit of any kind. Nothing is counted because there is nothing to count against: no account exists, no file reaches a server, and no quota can be enforced on work that happens in your own browser. That is worth saying plainly because it is where the free online signers differ most from each other. Of the five audited on 4 September 2026, two put a cryptographically verifiable signature behind a subscription, one allows a single saved signature before asking you to upgrade, and one asks for an email address on a page whose own title tag says "No Signup".
Images to PDF
Photos or scans into one PDF at full resolution, with a JPG going in as the bytes it already is.
Image to text
Read the words out of a scan or a photograph, with the recognition running in your own tab.
File transfer
Send the signed contract to your phone or your laptop directly, without it passing through anyone's storage.