DDanfio

Sign PDF

Some documents arrive with form fields waiting to be filled, and some arrive as a page that expects a pen. Both end the same way: the thing has to be filled in and signed, and most tools that do it want an account, a subscription and a copy of your document on their servers.

Drag & drop a file here, or .

Everything is processed in your browser - nothing is uploaded.

    One PDF up to 25 MB. It is opened in this tab, edited here and never uploaded.

    Fillable fields found in the PDF

    These come from the document itself, each one already holding the value the document has.

    Choose a PDF above and any fillable fields appear here.

    Drag & drop a file here, or .

    Everything is processed in your browser - nothing is uploaded.

      A PNG or JPG of your signature - most phones can photograph a signed slip of paper. Left blank, the typed name below is used instead.

      Drawn in the built-in Helvetica oblique, so it is a font rather than handwriting.

      Printed under the signature. Leave blank for no date.

      Only used by "the pages I list". Everything past the last page is trimmed, not an error.

      A picture keeps its own proportions and is never stretched.

      Flattening turns the filled fields into page content, so they can no longer be edited. It is not encryption.

      Leave blank to reuse the source name with -signed added.

      Only used for the plan below, before a PDF is chosen. The real job lists the document’s own fields.

      Results update as you type. Nothing leaves your device.

      Signature plan

      your-file-signed.pdf

      Add a PDF and its own fillable fields are listed for you to fill, then your signature is placed bottom right on last page.

      Fields in the plan
      3
      Signature on
      Last page
      Signature width
      2 in
      Flatten fields
      No

      What happens when you add a PDF

      1. The document is opened in this tab and every fillable field is listed with the value it already holds - no upload, no queue, no email address.
      2. You type into those fields. An untouched box keeps what the document had, and the fields themselves are edited, so bookmarks, page sizes and the rest of the document survive.
      3. Your signature - an uploaded picture, a typed name, or both - is drawn bottom right inside the page margins, with the width you choose.
      4. A download button appears for your-file-signed.pdf, with a table of every field that was filled.

      What signing here does and does not do

      FeatureIn the output
      Fillable text fieldsFilled with what you type, in the document’s own fields
      Check boxes, radio buttons, drop-downsSet to the choices you make
      Your signatureA picture you upload, or a name typed in Helvetica, drawn on the page
      A digital signatureNo: no certificate, no private key, no tamper evidence
      Bookmarks, page sizes, attachmentsKept: the document is edited rather than rebuilt
      Flattening (optional)Turns filled fields into page content that can no longer be edited

      A PDF field is a place in a document that expects a value; this page writes values into those places. A digital signature is a cryptographic seal over the whole file, which is a different thing entirely and is deliberately not faked here.

      This is not a digital signature. Nothing here uses a certificate or a private key, so the result cannot prove who signed it and a later edit is not detectable. It is the electronic equivalent of signing a printout and scanning it - fine for internal forms, consent slips and delivery notes, and not enough when the signature has to stand up to a challenge.
      Password-protected PDFs are refused rather than guessed at. The file never reaches a server, so there is nowhere to type a password: open it once with the password, save a copy without protection, then sign that.
      The field count above is a preview so the plan can be shown before you pick a document. When you add a PDF, its real fields are listed instead and the download button appears.

      This page does the work in the browser tab. The PDF is opened on your device, the fillable fields it already contains are listed for you to fill, and a signature - a picture you upload or a name you type - is drawn on the pages you choose. Nothing is uploaded, and the file you download is the one that never left your machine.

      How this sign pdf works

      It fills the fields the document already has

      A PDF form is a set of named fields plus places on the page where they appear, and the document stores both. This page reads those fields out of the file and shows one control per field: a text box for a text field, a tick for a check box, a list for a drop-down or a radio group. Every control starts with the value the document already holds, so changing one line does not mean retyping the whole form.

      Because the document is edited rather than rebuilt, everything else in it survives: bookmarks, page sizes, attachments, the order of the pages, the tags a screen reader uses. That is the difference between this page and a tool that copies pages into a new document - a page copy keeps what is visible and drops the paperwork.

      An electronic signature, described honestly

      What this page produces is a mark on a page: a picture of a signature, or a typed name drawn in the built-in Helvetica oblique font, placed inside the page margin. That is what most people mean by "sign this PDF", and it is exactly what printing, signing and scanning produces as well.

      It is not a digital signature. Nothing here signs with a certificate or a private key, so the file carries no proof of who signed it, and a change made to the file afterwards cannot be detected. A digital signature is a cryptographic seal over the whole document, issued through an identity check, and it is a different and much heavier piece of machinery - this page deliberately does not pretend to have it.

      Two consequences are worth knowing before you use it. A signature picture placed on a page is part of the page, so anyone with a PDF editor can copy it, move it or delete it. And flattening - turning the filled fields into page content - makes the answers awkward to edit, but it is not encryption and it does not lock the file.

      The small print that actually bites

      The font: Helvetica is one of the fourteen standard PDF fonts and covers Latin letters and common punctuation. A name in another script is refused with a clear message instead of printed as blank boxes - upload a picture of the signature in that case, because a picture has no alphabet to run out of.

      The fields: character limits and drop-down choices belong to the document, so an answer the field cannot hold is refused by name rather than quietly clipped in the output. Signature fields - the ones a real signing service would fill - are listed as not editable here, because filling one honestly needs a certificate.

      Encrypted files: if the PDF asks for a password it is refused. The document never reaches a server, so there is nowhere to type the password. Open it once in a viewer with the password, save a copy without the protection, and sign that copy.

      Worked examples

      Each example below was run through the calculator on this page when the site was built, so the numbers match what you see when you enter the same inputs.

      A contractor agreement with a name and two tick boxes

      Or type a name
      Jane Doe
      Date line
      14 September 2026
      Pages that get the signature
      Last page (the usual place)
      Where on the page
      Bottom right
      Signature width
      2 inches
      After filling
      Keep the fields editable
      Output file name
      —
      Preview: fillable fields
      3 fields

      Signature plan

      your-file-signed.pdf

      Add a PDF and its own fillable fields are listed for you to fill, then your signature is placed bottom right on last page.

      Fields in the plan
      3
      Signature on
      Last page
      Signature width
      2 in
      Flatten fields
      No

      The three fields the document already had are filled with the values shown, and the name and date are drawn in the bottom-right corner of the last page. The document keeps its bookmarks, because it was edited rather than rebuilt.

      A signature photographed on a phone

      Or type a name
      —
      Date line
      —
      Pages that get the signature
      Every page (initials style)
      Where on the page
      Bottom left
      Signature width
      1.5 inches
      After filling
      Keep the fields editable
      Output file name
      lease
      Preview: fillable fields
      6 fields

      Signature plan

      lease-signed.pdf

      Add a PDF and its own fillable fields are listed for you to fill, then your signature is placed bottom left on every page.

      Fields in the plan
      6
      Signature on
      Every page
      Signature width
      1.5 in
      Flatten fields
      No

      A picture of the signature is placed on every page at 1.5 inches wide, keeping its own proportions - the initials-on-every-page pattern a lease usually asks for.

      A consent slip with nothing fillable in it

      Or type a name
      Jane Doe
      Date line
      14 September 2026
      Pages that get the signature
      First page
      Where on the page
      Bottom centre
      Signature width
      2.5 inches
      After filling
      Flatten: make the values permanent
      Output file name
      consent
      Preview: fillable fields
      1 fields

      Signature plan

      consent-signed.pdf

      Add a PDF and its own fillable fields are listed for you to fill, then your signature is placed bottom centre on first page.

      Fields in the plan
      1
      Signature on
      First page
      Signature width
      2.5 in
      Flatten fields
      Yes

      A document with no fields at all still gets the signature, and the result says plainly that there was nothing to fill - so a stamped page is never mistaken for a filled form.

      Frequently asked questions

      Is this a real digital signature?

      No, and the result says so every time. What you get is a signature drawn on the page: a picture you upload, or a name typed in a standard font. It cannot prove to a third party who signed the document, and it does not detect later edits. A certificate-based digital signature does both, which is why it needs an identity check and a signing service - use one when the signature has to be verifiable.

      Is it free, and do I need an account?

      Free and account-free: no sign-up, no email step, no quota and no watermark on the output. The whole job runs in your browser, so there is no server cost to pass on to you and nothing to bill for. The limits are technical rather than commercial: one PDF per job, 25 MB for that file, held in the tab memory while you work on it.

      Is my contract uploaded anywhere?

      No. The document is read through the browser file API, edited in memory in that tab, and the download is a Blob URL created locally. Watch the network panel while you work, or disconnect from the internet completely - the flow is identical, because there is no upload endpoint behind this page.

      Why does the tool say the typed name is not handwriting?

      Because it is not. The name is drawn with Helvetica oblique, the same kind of font a document uses, so it reads as typed text rather than a signature. That is stated on purpose: if you need something that looks signed, upload a picture of your signature - a phone photo of a signed slip of paper works well and is placed at the width you choose.

      What does flattening do, and should I use it?

      Flattening turns each filled field into ordinary page content: the answers stay visible but can no longer be clicked into or edited, and the document stops being a fillable form. Use it when the file is going somewhere that might edit the answers, and skip it when you may want to change something later. It is not encryption and it does not protect the file.

      Can I sign a PDF that is protected by a password?

      Not directly, and deliberately so: the file never reaches a server, so there is nowhere to enter a password. Open the PDF once in a viewer with the password, save a copy without the protection, and sign that copy. The original stays protected and untouched on your device.

      Assumptions and sources

      • Processing: pdf-lib (MIT licensed) runs in your browser. The AcroForm fields the document already has are filled, their appearances are regenerated with a standard font, and the file is saved back with object streams so the page tree and bookmarks stay as they were.
      • Signature: an uploaded picture is embedded as image data, and a typed name is drawn as text with the standard Helvetica oblique font. No certificate, private key or timestamp is involved, so the output is an electronic mark rather than a digital signature.
      • Placement: the signature block sits half an inch inside the page edge, on the last page by default, and a picture keeps its own proportions - it is never stretched. A block wider or taller than the page allows is shortened to fit and the result says so.
      • Flattening: optional. It turns the filled fields into ordinary page content so they can no longer be edited, and it is not encryption - anyone with a PDF editor can still change the page itself.
      • Limits: one PDF per job, 25 MB per file, and no password-protected files, because the document never reaches a server and so there is nowhere to type a password.
      • Privacy: no document, field value or signature picture reaches danfio.com. There is no upload endpoint behind this tool and the download is a Blob held in your own tab.

      Last reviewed 2026-09-14. This page is an estimate tool, not financial, tax or legal advice.Read the full disclaimer.

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