PDF certificates vs verifiable credentials and Open Badges

The PDF: familiar, printable and editable

A PDF certificate resembles its paper counterpart: it can be printed, attached to an application and opened on any device. That familiarity is its strength. Its limitation is that it is only an image of a credential. A name or a date can be altered with a PDF editor, and nothing in an ordinary PDF informs the reader that this has occurred.

A PDF becomes reliable when it refers the reader to something verifiable: a verification link, a code, or a QR code leading to a page maintained by the issuer. The file is the reference; the check is the proof.

Verifiable credentials: a W3C standard

A verifiable credential is a digital document in a standard shape, carrying claims about someone (who they are, what they achieved, who says so) and a cryptographic proof from the issuer. The W3C Verifiable Credentials Data Model v2.0 became a W3C Recommendation on 15 May 2025. It defines how a credential names its issuer, its subject, when it becomes valid and, optionally, when it stops being valid.

Because the proof travels with the credential, software can check it without consulting the issuer's website: the signature confirms who issued it and that nothing has been changed. The digital signatures guide explains what that proof does and does not establish.

Open Badges 3.0: verifiable credentials for learning

Open Badges began as an idea from people at the Mozilla and MacArthur foundations at the 2010 Mozilla Festival. Mozilla launched Open Badges 1.0 in 2013, and IMS Global, now 1EdTech, took over its stewardship in 2017. Version 3.0 reached its final release on 27 May 2024; according to 1EdTech, it aligns with the conventions of the W3C Verifiable Credentials Data Model v2.0.

An Open Badges 3.0 credential describes an achievement (its name, description and criteria), the person who earned it and the organisation that issued it, in a format that badge platforms, wallets and learner records can read.

How revocation works in each

A certificate may need to be withdrawn following an error, a correction or a finding of misconduct. How that withdrawal reaches the reader depends on the format:

• PDF: the file cannot change once downloaded. Withdrawal only reaches readers who check the issuer's verification page.
• Verifiable credential: the credential can name an entry in a status list the issuer publishes. The W3C Bitstring Status List v1.0, also a Recommendation since 15 May 2025, keeps one bit per credential in a compressed list. It uses a minimum length of 131,072 entries so that fetching the list does not reveal which credential is being checked.

Comparison

Which one to issue

Both. The graduate needs a document to print and attach; the employer needs a link to open; an admissions system needs a file it can check automatically. A sound issuing system produces all three from the same record, so that they cannot diverge.

Emitcert follows this approach. Every certificate is a printable PDF, a verification page reachable by link or QR code, and an Open Badges 3.0 credential signed with the issuer's Ed25519 key, whose revocation status is published as a Bitstring Status List. The wording is fixed when the certificate is granted, so the three formats remain consistent. On presenting the credential professionally, see adding a certificate to LinkedIn.

In the European Union, the Commission's European Digital Credentials for Learning follow the same principle: Europass describes them as verifiable credentials in JSON-LD, aligned with the W3C standard and sealed by the issuer.