PDF became the default container for contracts for one reason above all others: it fixes the page. A Word document renders differently depending on the recipient's fonts, version, and page setup, and a clause that sits on page 4 for you may sit on page 5 for them. When the document is the agreement, that instability is unacceptable. A PDF looks the same to everyone, which is exactly what you want when parties are referring to "the third paragraph of clause 12."
What PDF does not automatically give you is tamper evidence — a common and consequential misunderstanding worth clearing up first.
What a signed PDF does and does not prove
A signature image — drawn, typed, or uploaded, then placed on the page — is a legally valid electronic signature in most jurisdictions. It is not, by itself, tamper-evident. Nothing in the file detects a later change. Someone could alter a figure after signing and the document would not object.
A certificate-based digital signature is a different mechanism. It computes a cryptographic hash of the document and binds it to a certificate issued to the signer. Any subsequent change breaks the hash, and the reader displays a warning. This is what genuinely provides tamper evidence and verified signer identity.
Both are useful; they answer different questions. For routine agreements the signature image plus an ordinary email trail is normal, sufficient, and what most business runs on. For high-value or contested-risk agreements, the certificate-based version — or a platform that maintains an audit trail — is worth the cost. See digital signatures vs electronic signatures.
Preparing a contract for signature
Finalise the text first. Every substantive change after signature requires re-signing or a formal addendum. Fixing a typo in an executed contract is not housekeeping — it is altering a signed instrument, and it undermines the document's integrity even when the change is genuinely innocent.
Make it readable. 11–12pt body text, clear headings, numbered clauses. Numbered clauses in particular are not decoration: they are how the parties will refer to the agreement for its entire life.
Add page numbers, ideally in "page 3 of 18" form so any recipient can tell whether they are holding the complete document. See how to add page numbers to a PDF.
Build proper signature blocks. Each party needs a signature line, a printed name, a title where signing on behalf of an entity, and a date field. Leave enough room — signature boxes that are too small produce marks sprawling over the terms beneath.
Export, do not print, to PDF. Use your application's Export or Save as PDF so internal links, bookmarks, and accessibility tags survive.
Send the right version. Naming files agreement-v4-FINAL-revised.pdf is how the wrong draft gets signed. Date-stamp versions and state in the covering email which one you are asking them to sign.
Getting it signed
For straightforward agreements, Docento.app lets a signer add a drawn, typed, or uploaded signature in the browser — free, no account, and the document is processed on their own machine rather than uploaded, which counterparties handling confidential terms tend to appreciate. See how to sign a PDF online.
For agreements where the evidence chain matters — high value, multiple parties, regulated sectors, or anywhere a dispute is foreseeable — a dedicated e-signature platform earns its fee. What you are buying is not the signature but the audit trail: timestamps, IP addresses, email verification, a record of who opened what and when, and a tamper-evident seal. That record is what you would need if the signature were ever challenged.
Before signing anything yourself: confirm the version matches what was negotiated, read the terms rather than assuming nothing changed since the last draft, check that every field requiring your input is completed, and date it.
After signature
Flatten it. Merging signatures and field values into the page content means they cannot be moved, deleted, or silently altered by whoever holds the file next. This is the single most useful post-signature step. See how to flatten a PDF.
Circulate the fully-executed copy. Every party should hold the same final version with all signatures present. Half-signed copies floating around cause real confusion later.
Name it usefully. 2026-02-16_ServiceAgreement_AcmeCorp_executed.pdf beats contract final signed(2).pdf when you need it in three years — and you will.
Store it in at least two places, one of them off your own machine. A contract that exists only on a laptop is one hardware failure from a difficult conversation. See backing up your PDF archive.
Never edit the executed copy. If terms need to change, that is an amendment or an addendum, signed by both parties, kept with the original.
Diarise the dates. Renewal windows, notice periods, and termination deadlines are in the document and nowhere else. A contract that auto-renewed because nobody read the notice period is a common and expensive mistake.
Negotiation and redlines
PDFs are the wrong tool for the negotiation phase. Exchange drafts in a format with proper tracked changes — Word or Google Docs — so every alteration is visible and attributable, and convert to PDF only for signature. Redlining in a PDF by annotation works for light comments but produces a much weaker record of who changed what.
If you are marking up a received PDF draft, annotation tools handle comments and queries well; see annotating a PDF. And if you need to share a draft with commercially sensitive sections removed, do it properly — a black box over text does not remove it. See how to redact text in a PDF.
The obvious but necessary caveat
The PDF is only the container. Nothing on this page addresses whether your contract terms are sound, enforceable, or appropriate for your jurisdiction. For employment contracts, partnership agreements, IP assignments, or anything with significant value at stake, have a lawyer review the substance. Getting the file format right is the easy half.
