Draw your signature, choose the page and corner, and the chain places it on the page, flattens any interactive form fields so their values become fixed content, then re-opens the file to confirm the signature image is in it, that no editable fields remain, and that the page count and text survived. A drawn signature is not a PKCS#7 certificate signature.
UnboundPDF is a free suite of 43 PDF and image tools that run entirely in your browser — merge, split, compress, edit text, OCR in 126 languages, redact, sign, convert and archive to PDF/A. Your document is read and written by the page on your own device; there is no document-upload endpoint in the core tools, no account, no watermark and no daily cap. Every result can be checked — with the Network tab, or with the Document Passport the Workspace writes for a chain of steps.
How it works, step by step
- Add the document you need to sign.
- Draw your signature in the pad and confirm it.
- Choose the page and the corner it should sit in.
- Run the chain — it places the signature, then flattens the form.
- Read the receipt, then download the signed file and its passport.
This produces a drawn signature — an image of your handwriting on the page. It is not a PKCS#7 / certificate-based digital signature, and nothing here claims otherwise.
What the chain does
Your drawing is captured as a PNG and embedded into the document with the same engine Fill & Sign uses, placed on the page and in the corner you pick, sized to a third of the page width. Then, if the document has interactive form fields, Flatten PDF’s form path bakes their values into the page content so nobody can retype them later. Finally the produced file is re-opened and checked. If there were no form fields, the receipt says exactly that rather than implying work that did not happen.
Fill the fields first if there are fields
This chain signs and flattens; it does not type into form fields for you. If your document is a real form with boxes to complete, fill it in Fill & Sign first — that tool lets you place text, ticks and a signature anywhere — and bring the completed file back here to flatten and verify. The step-by-step version lives in signing a PDF in the browser, and Sign PDF is the dedicated single-purpose tool.
The verification receipt
Six checks against the produced bytes: it re-opens as a PDF; its page count is unchanged; the page you signed carries an image of exactly the pixel dimensions your drawing was embedded at, which is how the signature is proved present rather than assumed (a form flatten adds appearance objects of its own, so counting objects would not do); no interactive form fields remain; the file is not encrypted; and its text layer is still readable. Anything that could not be checked says so.
What flattening does and does not freeze
It freezes form field values into page content. It does not make the document tamper-proof: the text is still text, and anyone with an editor can change it — including our own editor. Only a certificate signature makes a later change detectable, and we do not issue those. The passport’s SHA-256 is the closest substitute: it works when you send the recipient that hash by another route, so they can confirm the file they hold is the one you made.
The Document Passport
A small JSON with the chain, the steps, the checks and their real results, and the SHA-256 of the signed file. The hash proves these bytes are unchanged since the passport was written. It does not prove that you signed it, that the signature is yours, that the counterparty agreed, or that anything in the document is true. It is self-issued and unsigned. On a signing page in particular, that distinction has to be stated rather than implied.
Locking it down further
If the document must not be casually edited, Protect PDF adds a password and permission flags — real protection against opening, weak against a determined recipient. If the visual content must be genuinely fixed, the rasterising path in flattening without uploading turns pages into images, at the price of searchability.
Before you send it
A signed document is usually about to leave your hands, which makes it the right moment to check what else is inside it. Privacy Check & Clean scans for metadata, annotations and hidden-text indicators. If it also has to fit an inbox, Email Ready compresses toward the provider’s real cap. Both run in the same tab, on the same device.
Nothing is uploaded
A signature is biometric-adjacent data and a signed contract is somebody’s business, so the drawing never leaves the canvas and the document never leaves the tab. Verify that yourself with the PDF Privacy Lab; the comparison with upload-based signing services is on the compare page.
Frequently asked questions
Is a drawn signature legally binding?
That depends on your jurisdiction and the agreement, and no PDF tool can answer it for you. What this chain produces is an image of your handwriting baked into the page — the digital equivalent of ink on paper. It is not a PKCS#7 digital signature and carries none of its cryptographic guarantees.
What is the difference between this and a digital certificate signature?
A certificate signature cryptographically binds an identity, issued by a certificate authority, to the exact bytes of the document, and a reader can verify it and detect any later change. A drawn signature makes no such claim: it is a picture. We do not offer certificate signing, and we say so rather than blurring the two.
Why flatten after signing?
If the document had interactive form fields, their values stay editable until they are flattened — the recipient can change the number you typed. Flattening bakes the values into the page content, and the receipt confirms zero interactive fields remain in the output.
Can I still edit the document afterwards?
The text is still text, so it can still be edited — flattening freezes form field values, not the page. That is worth knowing in both directions: it is why the document stays searchable, and why a flattened file is not tamper-proof.