Signing a document used to mean printing it, signing it, scanning it and emailing back a crooked grey photograph. That still happens far more than it should. The useful thing to understand about electronic signatures is that the technical part is easy and the part everyone skips — what the signature actually evidences — is where the real differences between tools are.
Three Ways to Make a Signature
A signature on a PDF is a graphic placed at a position on a page. How you produce that graphic is a matter of what looks right and what is available to you.
Drawing is the most convincing, and a trackpad is worse at it than a finger or stylus on a touchscreen. If a mouse is all you have, expect to redraw it a few times — most people find their mouse signature looks nothing like their hand.
Typing your name in a cursive typeface is the fastest route and is perfectly ordinary for routine agreements. PDFixel offers six handwriting fonts; pick one and leave it alone, because the same name in three different scripts across a document set looks careless.
Uploading a photograph of a signature on paper gives the most faithful result. Sign a blank white page in dark ink, photograph it in even light, and the tool lifts the ink off the paper so it sits on the document rather than as a grey rectangle. This is the option worth setting up once and reusing.
- Draw — best on a touchscreen, worst with a mouse.
- Type — six cursive fonts, instant, fine for everyday agreements.
- Upload — photograph dark ink on plain white paper in even light.
- Size, colour, opacity and rotation from -180° to +180° are all adjustable once placed.
Make your signature once, then keep the image file. Reusing the same graphic across documents is both faster and more consistent than redrawing it every time.
Placing Fields and Assigning Signers
Most real documents need more than one mark. A contract wants a signature, a printed name and a date; a form may want initials on several pages; an approval may need two people.
Alongside signatures you can place date, name and checkbox fields, and assign each field to a participant with a defined role — Signer, Approver, CC or Witness. Each participant gets their own colour on the page, which is what makes a multi-party document readable while you are still setting it up rather than a confusion of identical boxes.
One practical detail that catches people out: scanned documents are frequently rotated. A page photographed sideways still displays correctly because the PDF carries a rotation instruction, and a signature placed on such a page has to be rotated to match or it lands in the wrong place at the wrong angle. PDFixel accounts for page rotation, so a signature goes where you put it at the size you set.
Work at a readable zoom. A signature that looks correctly placed at 50% zoom is often sitting a few millimetres off the line, and that is exactly the kind of detail a counterparty notices.
What a SHA-256 Summary Proves
PDFixel can append an optional final page recording the signers as they were entered, the time each placed their mark, and a SHA-256 fingerprint of the file as it was uploaded. The finished file's own fingerprint is shown in the tool rather than printed on the page, because a file cannot contain its own hash.
A SHA-256 hash is a fixed-length value computed from the exact bytes of a document. Change a single character anywhere in the file and the hash changes completely and unpredictably. So if you record the hash of the signed PDF somewhere outside the file — in an email, a case management system, a ticket — you can prove later that a document you are holding is byte-for-byte the one that was signed. Recompute the hash, compare, done.
That is genuinely useful and it is worth understanding precisely what it covers. The hash is evidence of integrity: this file has not been altered since the hash was taken. It is not evidence of identity, and it is not evidence of time.
The fingerprint only helps if you keep a copy of it somewhere other than inside the document. A hash stored only on the page it describes can be recomputed by anyone who edits the page.
What No Browser Tool Can Prove
This is the section most tools leave out, and it is the one worth reading.
The summary page is an ordinary page in an ordinary PDF. It is not a seal, it is not cryptographically bound to the document, and nothing in the file resists editing. Anyone can delete that page, or edit the document and produce a new one. Calling it tamper-proof would be false, so PDFixel does not.
The timestamps come from the clock on the machine that signed. Nothing verifies them. There is no timestamp authority in the pipeline, which means a time in the summary is a claim made by that computer, not an independently attested fact. A device with the wrong date produces a wrong time and the file looks no different.
Nor does any of this establish who held the mouse. An electronic signature of this kind carries no identity verification: there is no ID check, no email confirmation loop, no certificate tying the mark to a named person. For a routine agreement between parties who already know each other, that is normally fine — and it is also the entire difference between this and a qualified digital signature.
If you need cryptographic identity binding — a certificate issued to a verified individual, an attested timestamp from an authority, and a signature that a viewer can validate automatically — you need a qualified electronic signature from a trust service provider. That is a different product category, and honest software tells you when you have reached its edge.
- Integrity, if you store the hash separately: yes.
- A record of names and times as entered and as the signing machine saw them: yes.
- Protection against someone editing or deleting pages afterwards: no.
- Independently verified timestamps: no.
- Verified identity of the signer: no.
Whether an Electronic Signature Is Valid
Electronic signatures are recognised for most commercial and personal agreements across a wide range of jurisdictions — in the United States under the ESIGN Act and state UETA legislation, in the European Union under eIDAS, and under comparable frameworks elsewhere. The usual requirements are that the signer intended to sign, consented to doing so electronically, and that the signed record is retained and reproducible.
What those frameworks generally do not require is a particular technology. A typed name can satisfy them; a qualified certificate is not the baseline.
Specific document types are excluded in many places and the list varies: wills, certain trusts, some family law instruments, particular property transfers and a range of official filings may demand wet ink, notarisation or a qualified signature. The exclusions are jurisdiction-specific and they change.
This is a description of how the technology works, not legal advice, and nothing here should be read as a determination about your document. If the agreement carries real financial, employment or property consequences, confirm the requirements for your jurisdiction and document type before relying on any electronic signature — including this one.
Any tool that tells you its output is "legally binding" is overstating what software can determine. Validity depends on your jurisdiction, your document type and the circumstances of signing — none of which a browser can assess.
Summary
Signing a PDF in the browser is straightforward: draw, type or upload a signature, place it with date and name fields, assign roles where more than one person is involved, and export. An optional summary page records the signers, the times and the SHA-256 fingerprint of the original file, and the tool shows the signed file's own fingerprint, which proves that file has not changed since, provided you keep it somewhere outside the document. What it does not do is make the file tamper-resistant, verify the timestamps or establish who actually signed; the summary is an ordinary page and the times come from the signing machine's own clock. Electronic signatures are widely recognised for everyday agreements, certain document types are excluded depending on where you are, and no software can rule on the validity of your particular document.