Definition · W3C Verifiable Credentials
What is VCALM?
VCALM — Verifiable Credentials API Lifecycle Management, also known as the VC API — is an open W3C protocol for issuing, presenting, and verifying Verifiable Credentials over a single, simple exchange.
You'll see this protocol called both VCALM and the
VC API (or vc-api). They're the same thing:
the spec defines the VC API endpoints, and vcapi is the protocol
key you select on the wire. This site uses "VCALM" and "VC API"
interchangeably.
Think of it as the standard "plumbing" that moves a credential — a diploma, a product passport, a license — between three parties: the issuer who creates it, the wallet that holds it for the user, and the verifier who checks it. VCALM defines how those parties talk, so any conformant wallet works with any conformant issuer or verifier.
VCALM in one sentence for developers
The core delivery flow is a short HTTP loop: POST to an exchange
URL, read what the server asks for, POST the response back —
repeat until done. That's the entire piece that overlaps with the
OpenID-based specs (OID4VCI / OID4VP), and it's far smaller.
Common questions
What does VCALM stand for?
Verifiable Credentials API Lifecycle Management.
Is VCALM the same as the VC API?
Yes. "VCALM" and the "VC API" (or vc-api) refer to the same
W3C protocol. The specification defines the VC API endpoints, and
vcapi is the protocol key a wallet selects to use it.
Is VCALM a W3C standard?
Yes. VCALM is developed in the W3C Verifiable Credentials Working Group and published as a specification at w3.org/TR/vcalm.
How is VCALM different from OID4VCI / OID4VP?
OID4VCI (issuance) and OID4VP (presentation) are two separate OpenID-based protocols. VCALM handles both delivery and presentation in one exchange loop, keeps user choice of wallet, and works natively with W3C Verifiable Credentials. See Why VCALM for a full comparison.
What can you build with VCALM?
Anything that issues or verifies credentials: academic diplomas, product authenticity / digital product passports, professional licenses, and more. See the use-case guides.
Is VCALM hard to implement?
The delivery piece is short — a wallet implements three things. Start with the wallet quick start.
Ready to see it in practice?