Understanding Credential Formats: JSON-LD vs Signed PDF

This article explains the different formats in which Credentium credentials are issued and when to use each one.

Overview

When you issue a credential through Credentium, recipients receive it in multiple formats:

1. Signed PDF Certificate - A human-readable document with a Qualified Electronic Seal
2. JSON-LD Verifiable Credential - A machine-readable data format for automated processing
3. PNG Badge - A visual badge image for sharing

Each format serves a different purpose and has unique advantages.

Signed PDF Certificate

What It Is

A PDF document containing the credential information in a professional, printable format. The PDF is digitally sealed with a Qualified Electronic Seal (QES).

Key Characteristics

When to Use PDF

• Printing - When a physical copy is needed
• Traditional Institutions - Universities, government agencies that expect document format
• Visual Presentation - Job interviews, portfolio presentations
• Legal Proceedings - Courts and official processes

Verification Process

There are several ways to verify a signed PDF certificate:

Using Adobe Acrobat:

1. Open the PDF in Adobe Acrobat
2. Look for the "Signature Panel" or seal indicator
3. The reader will show:
   • Who sealed the document (organization name)
   • Whether the seal is valid
   • Whether the document has been modified

Using Credentium Validator:

• Visit validate.credentium.com and upload the PDF
• The validator will check the seal and display verification results

Using QR Code (Mobile):

• Each PDF certificate contains a QR code
• Scan the QR code with the Credentium Wallet mobile app (available for iOS and Android)
• The app will verify the credential and display its details

JSON-LD Verifiable Credential

What It Is

A standardized data format that represents the credential in a machine-readable way. JSON-LD (JavaScript Object Notation for Linked Data) uses W3C standards for Verifiable Credentials.

Key Characteristics

When to Use JSON-LD

• Automated Processing - HR systems, credential verification services
• Digital Wallets - Storing in Credentium Wallet, Europass, or other digital wallets
• API Integration - When systems need to programmatically verify credentials
• Cross-border Recognition - EU-wide interoperability with other credential systems
• Selective Disclosure - Future capability to share only specific credential claims

Structure

A Credentium JSON-LD credential contains:

{
  "@context": ["https://www.w3.org/2018/credentials/v1", ...],
  "type": ["VerifiableCredential", "EuropeanDigitalCredential"],
  "issuer": {
    "id": "...",
    "name": "Organization Name",
    "legalIdentifier": "..."
  },
  "credentialSubject": {
    "id": "...",
    "givenName": "...",
    "familyName": "...",
    "achievements": [...],
    "assessments": [...]
  },
  "issuanceDate": "...",
  "validFrom": "...",
  "validUntil": "...",
  "proof": {
    "type": "...",
    "created": "...",
    "verificationMethod": "...",
    "proofValue": "..."
  }
}

Verification Process

JSON-LD credentials can be verified using dedicated verification tools:

Using Europass Viewer:

• Visit the Europass Credential Viewer
• Upload or import the JSON-LD file
• The viewer will verify the cryptographic signature and display credential details

Using Credentium Validator:

• Visit validate.credentium.com
• JSON-LD verification support coming soon

Technical verification involves:

1. Extracting the proof section from the JSON-LD
2. Verifying the cryptographic signature against the issuer's public key
3. Checking the issuer's identity in a trusted registry
4. Validating the credential hasn't expired or been revoked

Comparison Table

European Digital Credentials (EDC) Compliance

Credentium credentials follow the European Learning Model (ELM) and are compatible with:

• Europass - EU digital portfolio and credential platform
• EBSI - European Blockchain Services Infrastructure
• eIDAS - EU regulation on electronic identification

This means credentials issued through Credentium can be:

• Stored in Europass digital wallets
• Verified across EU member states
• Recognized by institutions that accept EDC-compliant credentials

How Recipients Access Both Formats

When a credential is issued, recipients can access all formats through:

Credentium Wallet

1. Log in to the Credentium Wallet
2. Go to My credentials
3. Click View Credential
4. Use the download buttons:
   • Download PDF Certificate - Gets the sealed PDF
   • Download JSON-LD - Gets the machine-readable format
   • Download Badge - Gets the PNG badge image

Email Notification

Recipients receive an email with:

• Link to view the credential in their wallet
• Direct access to the PDF certificate

Storage Recommendations

For Recipients

• Keep both formats - PDF for human-readable needs, JSON-LD for digital verification
• Store in Credentium Wallet - Easy access to both formats
• Backup to Europass - EU digital portfolio for long-term storage

For Issuers

• Both formats are automatically generated and stored by Credentium
• No additional action needed - the system handles both formats

Frequently Asked Questions

Can I issue only PDF without JSON-LD?

No. Credentium always generates both formats to ensure maximum interoperability and future-proofing.

Which format should recipients share with employers?

Depends on the employer's preference:

• Traditional employers: PDF certificate
• Tech companies/HR systems: JSON-LD for automated verification
• When in doubt: Share the wallet link, which provides access to both

Is JSON-LD secure without a visual seal?

Yes. JSON-LD uses cryptographic signatures that are mathematically verifiable. The security is equal to or greater than a visual PDF seal.

Can credentials be modified after issuance?

No. Both PDF (seal) and JSON-LD (signature) are invalidated by any modification. This is a security feature.

What if a verification system doesn't support JSON-LD?

Share the PDF certificate. As EDC adoption grows, more systems will support JSON-LD verification.

Need Help?

If you have questions about credential formats, please contact:

Credentium Support Email: support@credentium.com

Last updated: January 2026