Sign PDF Online – Add an Electronic Signature

Upload a PDF to sign it using the built-in PDF.js viewer. Look for the signature / pen tool in the toolbar to add your signature.

Click to select a file or drag and drop

PDF Documents

Your files never leave your device.

What does this PDF signing tool do?

This tool places a visible electronic signature on a PDF. You can draw a mark, type your name in a signature-style font, or upload a signature image, then position it on the document. Processing happens locally in your browser.

It does not issue a signing certificate, verify a signer's identity, create a cryptographic digital signature, or provide an independent audit trail. Those features require a certificate-based signing service.

Why add an electronic signature?

  • Convenience: Complete routine document workflows without printing and scanning
  • Time Saving: Sign documents instantly without printing or scanning
  • Privacy: Keep the document on your device during browser-based signing
  • Cost Effective: Eliminates paper, printing, and postage costs
  • Eco-Friendly: Reduces paper consumption and carbon footprint
  • Remote Collaboration: Sign documents from anywhere in the world

Key Features

  • ✓ Draw signature with mouse/touch
  • ✓ Type signature with fonts
  • ✓ Upload signature image
  • ✓ Position and resize freely
  • ✓ Flatten signatures
  • ✓ 100% free & secure

Electronic signature vs certificate-based digital signature

Electronic signature added by PDFup

  • A visible drawn, typed, or uploaded signature mark.
  • Useful for routine approvals and documents when the parties accept this method.
  • Can be flattened into the page to make casual removal more difficult.
  • Does not independently verify identity or create a certificate chain.

Certificate-based digital signature

  • Uses cryptographic keys and a signing certificate.
  • Can help a compatible reader detect changes made after signing.
  • May include identity validation, timestamps, or an audit record.
  • Requires a suitable certificate or specialized signing provider; PDFup does not provide this workflow.

How to Sign PDF Online

1

Upload PDF

Select the PDF document you need to sign. Our tool works entirely in your browser - your files never leave your device.

2

Add Signature

Use the signature tool in the PDF viewer. Choose to draw, type, or upload your signature. Position it anywhere on the document.

3

Download & Save

Download your signed PDF. Optionally flatten the signature to make it non-editable. Your original file remains unchanged.

Signature Methods

Draw Signature

Use your mouse, touchpad, or touchscreen to draw your signature freehand.

Best for: Personal touch

Type Signature

Type your name and choose from multiple signature-style fonts.

Best for: Consistency

Upload Image

Upload a scanned image of your handwritten signature.

Best for: Exact replica

Best Practices for Signing a PDF

Recommended Practices

  • Use "Flatten PDF" option to prevent signature removal
  • Position signature near signature lines if present
  • Save a copy of your signature image for future use
  • Verify document content before signing

Legal Considerations

  • Validity depends on applicable law, document type, the parties' intent, and available evidence
  • Some documents may require certified digital signatures
  • For highly sensitive documents, consult legal advice

Prepare, sign, and share the document carefully

  1. Review the complete document. Confirm names, dates, amounts, attachments, and blank fields before adding a signature.
  2. Choose an appropriate method. Draw for a handwritten appearance, type for consistency, or upload a clean transparent PNG when you need a reusable visual mark.
  3. Place the signature deliberately. Keep it inside the intended signature area and avoid covering terms, dates, or other fields.
  4. Decide whether to flatten. Flattening makes the visual mark part of the page content, but it is not tamper-proof and does not replace certificate-based validation.
  5. Save and verify the result. Open the downloaded copy, inspect every signed page, and retain the agreed final version.

For a fillable document, complete existing fields with PDF Form Filler before signing. Afterward, consider Encrypt PDF when the recipient should need a password, or Sanitize PDF when hidden information is a concern.

Frequently Asked Questions

There is no universal yes-or-no answer. Enforceability can depend on the applicable law, document type, the parties' intent and consent, identity evidence, record retention, and any formal requirements such as witnesses or notarization. PDFup adds a visible electronic signature but does not verify identity or provide a certificate-based signature. For high-value, regulated, or disputed transactions, obtain advice appropriate to your jurisdiction and use a signing method that meets the required standard.

These terms are often used interchangeably but have technical differences:

  • Electronic Signature: Any electronic symbol attached to a document (what our tool provides)
  • Digital Signature: Uses encryption technology to verify authenticity (requires certificates)
  • Legal effect: Acceptance depends on the transaction, evidence, agreement, and applicable law
  • For formal needs: Consider certified digital signature providers

With the "Flatten PDF" option, the visible signature becomes part of the page content and is harder to remove casually. Flattening is not tamper-proof and does not prove who signed the file. Consider these measures:

  • Always use the "Flatten PDF" option before sharing
  • Password protect your PDF after signing
  • Use an appropriate certificate-based signing service when identity validation or tamper evidence is required
  • Keep original signed copies for verification

For maximum security, consider our PDF encryption tool after signing.

Our tool supports various image formats for signature uploads:

  • Recommended: PNG with transparent background
  • Also supported: JPG, JPEG
  • Best practice: White signature on transparent background
  • Image size: 300-600 pixels wide for optimal quality

Tip: Create your signature using our PDF Editor tool and save it as an image for reuse.

Our current tool supports single PDF signing. For multiple documents or batch processing:

  • Sign each document separately
  • Use our Merge PDF tool to combine documents first
  • For multiple signatures on one document, place them on different pages
  • Save your signature image for quick reuse across documents

Complete signing workflow

Fill, sign, flatten, and verify in the right order

Use the workflow guide to distinguish visible electronic signatures from certificate-based signing and to prepare a consistent final copy.

Open the fill and sign cheat sheet →

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