How to Check PDF Digital Signature with signNow

TL;DR

Check a PDF digital signature by verifying the signer identity, certificate validity, and integrity using a trusted viewer or signNow's audit trail. signNow records signer details, timestamps, and a cryptographic audit trail so recipients and administrators can confirm a document was not altered and that signing complied with ESIGN and UETA.

What checking a PDF signature means

Checking a PDF digital signature is like confirming a sealed envelope has not been opened and that the sender is who they claim to be. In plain terms, you look at the signature details, verify the signing certificate, and confirm the document hash matches the original. With signNow, this process is integrated into electronic workflows: users can fill and sign forms online, view audit trails, and validate signatures without printing or scanning, giving a clear record of who signed, when, and how.

Legal and operational importance

Validating PDF digital signatures protects enforceability and data integrity under ESIGN and UETA, and reduces risks in remote transactions. Use signNow to maintain compliant records, verify signer identity, and retain auditable evidence for legal or regulatory review.

Common verification challenges

• Signer certificate is expired or revoked, causing viewer trust warnings and potential invalidation of the signature.
• Document was altered after signing, which breaks the signature hash and requires review of the audit trail and file versions.
• Absence of certificate chain trust in the viewer, meaning the signer’s certificate is not from a trusted authority.
• Confusion between visible signature image and cryptographic signature—visual marks can be copied without a valid digital signature.

Who relies on PDF signature checks

Verifying PDF signatures reduces legal risk and speeds approval cycles for contract-driven workflows across these sectors.

• Real Estate professionals verifying leases and closing documents on mobile or desktop.
• Healthcare and life sciences teams confirming patient consents and HIPAA-sensitive forms.
• Finance and legal departments validating contracts, tax forms, and client approvals.

Who in your organization

IT Administrator

IT administrators configure signNow integrations, manage SSO and security settings, and ensure certificate-management and API access conform to organizational policies. They use audit logs and platform controls to monitor signature verification and retention, and to support compliance audits.

Legal Counsel

Legal teams review signature validity and audit trails to determine contract enforceability. They rely on signNow's ESIGN/UETA compliance features and exported evidence when preparing for disputes, audits, or regulatory filings.

Security and compliance facts

Encryption in transit: TLS 1.2 and 1.3

Encryption at rest: AES-256 encryption

Audit standard: SOC 2 Type II certified

Healthcare compliance: HIPAA — BAA required

Regulatory support: ESIGN and UETA compliant

International standards: ISO 27001 certified

Risks of unchecked signatures

Invalid contracts: Enforceability disputes

Regulatory fines: HIPAA or CCPA penalties

Data breaches: Exposure of sensitive records

Operational delays: Contract processing halted

Reputational harm: Loss of customer trust

Audit failure: Noncompliance findings

Real-world examples

Two short case studies show how organizations use signNow to verify and manage signed PDFs with audit-ready evidence.

Optica Ventures LLC — Brian Fitzgibbons

Optica uses a simple signing flow to capture customer signatures online and reduce turnaround time.

• The team leverages signNow mobile signing and templates to standardize agreements.
• That standardization improved sign-back speed and reduced missing fields.

Resulting in faster closings and higher customer satisfaction across remote deals.

Xerox — Kodi-Marie Evans

Xerox integrated signNow with NetSuite to route documents and confirm signer identity automatically.

• Integration preserves certificate details and timestamps in each record.
• IT and operations can retrieve audit trails instantly for compliance checks.

Leading to consistent process controls and reliable evidence during audits and vendor validations.

Step-by-step verification checklist

Follow these clear steps in signNow or a trusted PDF viewer to verify a digital signature and confirm document integrity.

• 01
  Upload Document: Open signNow, click Upload, select your PDF file, and confirm import into your workspace.
• 02
  Open Signature Details: In signNow or your PDF viewer, open the signature panel to display signer certificate and timestamp information.
• 03
  Verify Certificate: Check the certificate issuer, validity dates, and trust chain to confirm issuer is trusted and certificate is valid.
• 04
  Review Audit Trail: Open signNow's audit trail to confirm signer email, IP address, timestamp, and any authentication steps used.

How verification works technically

Verification combines cryptographic checks, certificate trust, and platform audit logs to determine if a PDF signature is valid and untampered.

• Document hashing: Hash generated and checked against signature
• Certificate check: Validate issuer and expiration status
• Trust chain: Confirm chain links to trusted CA
• Audit evidence: Use signNow logs to confirm signer actions

Core features for signature validation

Key signNow capabilities simplify checking and managing PDF digital signatures within enterprise workflows while preserving compliance and traceability.

Audit Trail

Comprehensive, timestamped record of signing events, including signer email, IP address, authentication method, and document version history for legal and compliance review.

Certificate Support

Support for electronic signature certificates and eIDAS SES with options for advanced signatures on Site License plans, enabling cryptographic validation where required by jurisdiction.

Bulk Send

Send the same document to many recipients and capture individual signatures and audit trails; available on Business Premium to streamline high-volume signature collection.

Mobile Signing

Native mobile apps for iOS and Android that permit secure signing, verification, and offline signing capabilities with later synchronization when back online.

Advanced features and integrations

signNow includes a range of advanced capabilities and integrations that support verification, automated workflows, and system-wide signature validation.

Integrations

Prebuilt connectors for Salesforce, NetSuite, Google Workspace, Box, and more to route signed PDFs and verification metadata into enterprise systems.

API Access

Full signNow API enabling automated document preparation, signature requests, and retrieval of audit logs for programmatic verification and archival.

Conditional Fields

Enterprise-level conditional and formula fields to enforce data collection rules before signatures are accepted and recorded in the audit trail.

Payments and Kiosk

Payments and kiosk signing options on higher tiers to capture signatures with payment confirmation and in-person signing evidence where required.

Templates

Reusable templates that predefine signature locations and required fields to reduce errors and ensure consistent verification metadata.

Offline Mode

Offline signing support for mobile, storing signed data locally and syncing later to preserve audit integrity when connectivity returns.

Best practices for checking signatures

Adopt consistent verification practices to ensure signatures are valid, tamper-evident, and legally defensible across business processes.

Confirm certificate trust chain and validity

Always inspect the certificate issuer, expiration date, and whether the certificate chains to a trusted Certificate Authority before accepting a signature as valid.

Use multi-factor signer authentication

Combine email verification with SMS or access codes in signNow to strengthen signer identity and record robust authentication evidence in the audit trail.

Retain original signed copies and exports

Store original signed PDFs and export audit trails to secure cloud storage or an ECM system for long-term retention and regulatory compliance.

Train staff on signature checks

Provide role-specific guidance for legal, sales, and operations teams on where to verify signature details, interpret audit logs, and escalate anomalies.

Manage the audit trail

Use the audit trail to confirm signer identity, authentication, timestamps, and document integrity when checking PDF digital signatures.

01

View Trail:

Open the document's Audit Trail pane in signNow.

02

Inspect Events:

Review signer events, timestamps, and IP addresses.

03

Export Log:

Download the audit trail for offline storage.

04

Check Hash:

Confirm document hash matches signed file.

05

Validate Auth:

Ensure authentication steps recorded are complete.

06

Archive Evidence:

Store audit logs with the signed PDF.

FAQs About checking PDF signatures

Answers to common verification problems and troubleshooting steps when a PDF signature appears invalid or when signNow reports verification issues.

• Why does the signature show invalid?
  A signature appears invalid when the document was modified after signing or the signing certificate is expired or revoked. Confirm file integrity, check the certificate validity dates, and review the signNow audit trail to identify the point of modification or an authentication failure.
• How do I verify the signer identity?
  Check the signer email and authentication method recorded in signNow, then review any additional identity verification steps such as SMS codes or knowledge-based authentication used during signing to confirm the signer's identity.
• Can I validate a signature offline?
  signNow supports offline signing on mobile with later synchronization; however, certificate revocation checks require online access to verify CRLs or OCSP status when confirming certificate validity.
• What if the certificate issuer is untrusted?
  If the viewer does not trust the certificate issuer, obtain the certificate chain or contact the signer. In signNow workflows, maintain organizational policy about acceptable CAs and escalate untrusted certificates to legal or security teams.
• How do I export verification evidence?
  Use signNow's export functions to download the signed PDF and its full audit trail as a single package for storage or legal review. Retain those files in your secure document repository.
• Which signNow plan includes advanced verification?
  Advanced signer authentication, bulk send, and integrations are available on Business Premium and Enterprise plans; Site License supports advanced signature types and additional compliance controls.

When to perform checks

Define checkpoint deadlines in your signing workflows to ensure validity checks are performed when they matter most.

01

Before finalizing deals

Verify signatures before contract execution and fund transfer.

02

Before compliance audits

Check audit trails when preparing for regulatory review.

03

After mass distribution

Confirm signature validity following bulk send campaigns.

04

When certificates change

Re-verify signatures if CA or certificate policies update.

Retention and review schedule

Set dated review and retention rules for signed PDFs to meet legal and operational requirements.

Daily review window:

First 24 hours after signing

Quarterly audit:

Every 90 days for critical contracts

Annual compliance check:

Yearly review of audit logs and retention

Retention period:

Keep signed copies at least 7 years

Certificate renewal review:

Review on CA certificate renewal dates

Verification milestones

Track milestones in signing workflows so checks occur at predictable points from document creation to archival.

01

Draft Complete

Template and fields finalized

02

Pre-Send Audit

Verify fields and signer requirements

03

Sign Event

Collect cryptographic signature and timestamp

04

Post-Sign Check

Validate certificate and integrity

05

Export Evidence

Download signed PDF and audit trail

06

Archival

Store in secure repository

07

Periodic Review

Scheduled compliance spot checks

08

Disposition

Follow retention policy for deletion

Where to check signatures

You can verify PDF signatures in signNow web app, mobile apps, or in a trusted PDF reader that supports certificate validation.

• Web browsers: Chrome, Edge, Firefox supported
• Mobile apps: iOS and Android apps available
• API access: Programmatic verification via API

For best results, use signNow's apps or integrations to preserve audit metadata, access certificate details, and automate verification in your existing systems.

Recommended workflow settings

Suggested signNow settings to ensure signatures are captured, verified, and retained with required audit evidence.

Setting Name	Configuration
Authentication Method	Email and SMS
Reminder Frequency	48 hours
Signer Order	Sequential
Audit Trail	Enabled
Document Retention	365 days

Quick capability comparison

At-a-glance availability of core verification capabilities among signNow, DocuSign, and Adobe Sign for common signing needs.

Feature / Criteria	signNow	DocuSign	Adobe Sign
Certificate signatures
Bulk send		limited
Mobile signing
Envelope cap	no cap	100/year	no cap

Pricing and compliance snapshot (data current as of dataset)

Compare starting price, trial, bulk send, audit trail, HIPAA support, and envelope caps across signNow and common competitors using verified plan-level data where available.

	signNow	DocuSign	Adobe Sign	PandaDoc	HelloSign
Starting Price	$8/user/mo	$8/user/mo	$13/user/mo	$19/user/mo	$15/user/mo
Free Trial	7-day trial, no card	Varies by vendor	Varies by vendor	Varies by vendor	Varies by vendor
Bulk Send	Yes — Business Premium	Yes — add-on/pricing	Yes — select plans	Yes — included	Yes — business plan
Audit Trail	Yes — full audit trail	Yes — full audit trail	Yes — full audit trail	Yes — audit logs	Yes — audit logs
HIPAA Compliant	Yes — BAA required	Yes — BAA likely	Yes — BAA available	Contact vendor	Contact vendor
Envelope Cap	No envelope cap	100 envelopes/user/year	No envelope cap	No envelope cap	No envelope cap