PDF Signer & Validator

Whether you need to return a countersigned employment offer, initial every page of a commercial lease, or stamp a company seal onto a purchase order, you can sign PDF online free right inside your browser. Draw a pressure-smoothed signature with your mouse, trackpad, or stylus, type your name in a stylized script font, or drop a transparent PNG image of your wet-ink signature onto any page without uploading confidential contracts to an external e-signature cloud.

Moments when you just need a signature on the page

Enterprise e-signature platforms are built for multi-party legal workflows with email routing, reminders, and server audit trails, but they are overkill when someone emails you a PDF attachment and asks you to sign and send it back. Registering for an account, uploading a private agreement to a third-party server, and hitting a three-document monthly paywall turns a thirty-second task into an obstacle course.

Common everyday situations where local signing fits naturally include:

• Employment offers and NDAs: Counter-signing an offer letter, non-disclosure agreement, or contractor onboarding packet and emailing the flattened PDF straight back to HR.
• Landlord and tenant leases: Placing full signatures on the final execution page alongside quick initials and today's date in the bottom corner of every preceding page.
• Reimbursement and tax declarations: Signing scanned expense claims, vendor invoices, self-declaration forms, or board resolutions before uploading them to a finance portal.
• Company stamps and seals: Overlaying a transparent PNG of an official corporate rubber stamp or authorized signatory seal on pro-forma invoices and delivery notes.

How to sign PDF online free step by step (3 workspace modes)

The top navigation bar switches between three distinct signing and verification workflows depending on whether you need a visual ink signature, a cryptographic X.509 certificate signature, or a forensic signature audit:

Method 1: Visual Electronic Signature (1. E-Sign Tab: Typed, Drawn, or Custom Seal)

1. Load your PDF document: Drag your file into the left viewer panel or click Select PDF File to render the pages on the canvas.
2. Choose your signature source sub-tab:

• Typed: Enter your full name and pick from 8 handwritten script fonts (Caveat, Dancing Script, Great Vibes, Pacifico, Sacramento, Alex Brush, Satisfy, Allura).
• Trackpad Draw: Sketch your handwritten signature directly on the touch/mouse canvas pad.
• Upload Seal/Signature: Import a transparent PNG, JPG, or SVG of your wet-ink signature or corporate rubber stamp.

1. Pick your ink color and metadata stamps: Select Navy Blue, Royal Blue, Black, Dark Green, or Dark Red, and optionally check Include Date stamp, Include Time stamp (UTC), or Include WebCrypto SHA-256 Digest.
2. Place, drag, and export: Click Place Signature on Document, drag the #sigStamp overlay to the exact signature line on any page, and click Generate & Download Signed PDF to flatten the signature permanently into the page content stream.

Method 2: Cryptographic PKI Digital Signature (2. Digital Signature (PKI) Tab)

1. Switch to the 2. Digital Signature (PKI) tab in the top bar after loading your PDF.
2. Select your Certificate Source:

• Choose Upload Certificate (.pfx / .p12) to select your PKCS#12 file and enter its decryption password, or
• Choose Generate Development Certificate (For Testing), enter a Common Name (CN) and Organization (O), and click Generate Self-Signed X.509 Pair.

1. Inspect the parsed certificate details: Verify the Subject CN, Issuer, and Serial readout displayed in the green confirmation box, and enter your Signing Reason (e.g., "I approve the contents of this document").
2. Click Apply Cryptographic Digital Signature & Save PDF: The engine computes the SHA-256 byte-range digest and embeds a standard PKCS#7 / CMS (/Sig) signature dictionary into the exported PDF.

Method 3: Verify an Existing Signed PDF (3. Validate PDF Tab)

1. Switch to the 3. Validate PDF tab and load the signed PDF document you want to inspect.
2. Click Analyze & Validate Loaded Document: The validator parses the PDF's internal /Sig and /ByteRange structures, recalculates the SHA-256 hash over the signed byte ranges, and inspects the embedded X.509 certificate chain.
3. Review the audit readout and export: Check the Signer Subject (CN), Issuer Authority, Signature Algorithm, SHA-256 Byte Hash, Document Integrity, and Certificate Validity status, then click Export Audit Report PDF if you need a standalone verification record.

A real example: countersigning a 6-page consulting agreement

Suppose a client sends Consulting_Agreement_Q4.pdf (6 pages, 410 KB). Page 6 has a signature block requiring your signature, date, and document checksum.

1. Open Consulting_Agreement_Q4.pdf in 1. E-Sign mode.
2. Select Trackpad Draw, choose Navy Blue (#1e3a8a), and sign your name on the canvas pad.
3. Check Include Date stamp, Include Time stamp (UTC), and Include WebCrypto SHA-256 Digest.
4. Jump to Page 6 (Page 6 / 6 in the bottom toolbar), click Place Signature on Document, and drag the stamp overlay directly onto the Authorized Representative line.
5. Click Generate & Download Signed PDF. The flattened contract downloads immediately with the ink signature, UTC timestamp, and SHA-256 digest baked into Page 6.

Capabilities built into the signature & PKI workspace

Three visual signature modes with live SHA-256 stamp option

On a tablet, phone, or laptop with a precision trackpad, the Trackpad Draw pad renders clean ink strokes. On a desktop with a mouse, the Typed tab previews your name across 8 cursive fonts in real time, while Upload Seal/Signature places official company stamps with alpha transparency. You can even append a live WebCrypto SHA-256 Digest and UTC timestamp directly onto the visual stamp block.

Client-side PKCS#7 / CMS (.pfx / .p12) signing & X.509 audit

Unlike basic canvas tools that only paste a bitmap picture onto a page, the Digital Signature (PKI) and Validate PDF modes inspect and construct real PDF /Sig dictionaries locally in browser memory - letting you test X.509 workflows or verify whether a signed PDF was modified after signing without uploading confidential legal files to a third-party server.

Visual e-sign vs. cryptographic PKI signature verification tips

• Commercial e-signatures vs statutory hardware tokens: Under the US ESIGN Act and EU eIDAS, electronic signatures are accepted for routine commercial agreements. However, drawn signatures or self-signed browser certificates do not replace licensed hardware USB DSC tokens or government Aadhaar eSign where required by statute (and cannot be used for wills, trusts, or real estate conveyances).
• Photographing a paper signature: If you sign white paper with a dark pen and photograph it, run the photo through the Background Remover first so the paper background becomes 100% transparent before uploading it under Upload Seal/Signature.
• Locking form fields first: If your PDF contains interactive text inputs, fill and flatten them in Fill & Flatten PDF Forms before applying your final signature.

Privacy and local execution

Contracts, tax forms, and offer letters carry sensitive financial and personal data. This PDF signer runs 100% inside your browser using local HTML5 Canvas rendering and pdf-lib manipulation. The source code makes zero fetch, XMLHttpRequest, or WebSocket calls with your document or signature image. Neither your PDF nor your drawn signature ever leaves your device.

Companion PDF form filling and protection tools

Need to complete text fields and checkboxes before signing? Open Fill & Flatten PDF Forms. To lock the signed contract with an AES password, use Password Protect PDF, or redact confidential account numbers first with Redact PDF. For a complete walkthrough, read our guide on how to sign a PDF online for free.