Verifiable Credentials API | Issue and Verify Credentials

In this quickstart you will learn how to create, issue, and verify credentials.

What are credentials?

A digital credential is an electronic record issued by a trusted source that certifies specific information about a person or entity. Crossmint makes it easy to issue, manage, and verify credentials onchain, following the W3C VC standard. For a comprehensive guide on Verifiable Credentials, please visit the Verifiable Credentials section.

Verifiable Credentials is an Enterprise feature. Contact Sales for access.

Integration steps

1. Create a Developer Account

To get started, create a developer account in the Crossmint Staging Console. Open that link, sign in, and accept the dialog to continue.

Crossmint offers two consoles: staging, for development and testing, and production.

2. Get an API Key

Once you log in to the console, the next step is to create an . Click the "Integrate" tab and click on the "API Keys" option on top. Within the “Server-side keys” section, click the “Create new key” button in the top right. Then, check the scopes credentials.create, credentials.read, and credentials:templates.create under the “Verifiable Credentials” category and create your key. Save this key for the next step.

3. Create a Credential Template

To mint a credential, we need to create a credential template that follows an already defined credential type. In this quickstart we will use the already-created CourseCompletionCertificate type.

createTemplate.js

const apiKey = "YOUR_API_KEY";
const env = "staging"; // or "www"

const url = `https://${env}.crossmint.com/api/v1-alpha1/credentials/templates`;
const options = {
    method: "POST",
    headers: {
        accept: "application/json",
        "content-type": "application/json",
        "x-api-key": apiKey,
    },
    body: JSON.stringify({
        credentials: {
            type: "crossmint:bedea4c5-4cea-425b-99c7-797ecbc8bc13:CourseCompletionCertificate",
            encryption: "none",
            storage: "crossmint",
            subject: {
                properties: {
                    course: {
                        type: "string",
                        title: "Course",
                        description: "Course name",
                    },
                    grade: {
                        type: "string",
                        title: "Grade",
                        description: "Grade received",
                    },
                },
                required: ["course", "grade"],
            },
        },
        metadata: {
            name: "Certificate of Completion",
            description: "A certificate issued upon completion of a course",
            imageUrl: "https://www.crossmint.com/assets/crossmint/logo.png",
        },
        chain: "polygon-amoy",
    }),
};

fetch(url, options)
    .then((res) => res.json())
    .then((json) => console.log(json))
    .catch((err) => console.error("error:" + err));

Example response

JSON

{
  "id": "a9e3016b-66f0-40ab-8d72-6546fddc7b72",
  "metadata": {
    "description": "A certificate issued upon completion of a course",
    "name": "Certificate of Completion",
    "imageUrl": "ipfs://QmaToZn4VEjF7q4CAudPaNka6AD484xuuEZSXmTLJPDLVE"
  },
  "fungibility": "non-fungible",
  "onChain": { "chain": "polygon-amoy", "type": "erc-721" },
  "subscription": { "enabled": false },
  "actionId": "a9e3016b-66f0-40ab-8d72-6546fddc7b72"
}

Save the id from the response as your TEMPLATE_ID for the next step.

4. Issue a Credential

Now, let’s issue a credential using our template:

issueCredential.js

const apiKey = "YOUR_API_KEY";
const env = "staging"; // or "www"
const templateId = "YOUR_TEMPLATE_ID";
const recipientEmail = "TEST_EMAIL_ADDRESS";

const url = `https://${env}.crossmint.com/api/v1-alpha1/credentials/templates/${templateId}/vcs`;
const options = {
    method: "POST",
    headers: {
        accept: "application/json",
        "content-type": "application/json",
        "x-api-key": apiKey,
    },
    body: JSON.stringify({
        recipient: `email:${recipientEmail}:polygon-amoy`,
        credential: {
            // The CourseCompletionCertificate credential type requires course and grade declarations
            subject: {
                course: "Blockchain 101",
                grade: "A",
            },
            expiresAt: "2034-02-02",
        },
    }),
};

fetch(url, options)
    .then((res) => res.json())
    .then((json) => console.log(json))
    .catch((err) => console.error("error:" + err));

Example response

JSON

{
  "id": "6728f773-61af-4732-a34f-b5a50d8b9872",
  "onChain": {
    "status": "pending",
    "chain": "polygon-amoy",
    "contractAddress": "0x45c9597b5441289C134E554990cdb647f65df5FB"
  },
  "credentialId": "urn:uuid:e6b3dc76-a337-437b-ac1b-3d330e66e1a6",
  "actionId": "6728f773-61af-4732-a34f-b5a50d8b9872"
}

Save the credential id from the response for the next step.

5. Retrieve a Credential

To retrieve a credential:

getCredential.js

const apiKey = "YOUR_API_KEY";
const env = "staging"; // or "www"
const credentialId = "YOUR_CREDENTIAL_ID";

const url = `https://${env}.crossmint.com/api/v1-alpha1/credentials/${credentialId}`;
const options = {
    method: "GET",
    headers: {
        accept: "application/json",
        "x-api-key": apiKey,
    },
};

fetch(url, options)
    .then((res) => res.json())
    .then((json) => console.log(json))
    .catch((err) => console.error("error:" + err));

Example response

JSON

{
  "unencryptedCredential": {
    "id": "urn:uuid:e6b3dc76-a337-437b-ac1b-3d330e66e1a6",
    "credentialSubject": {
      "course": "Blockchain 101",
      "grade": "A",
      "id": "did:polygon-amoy:0x2da3151C266185c4861b45277dbbe56Cb613963e"
    },
    "validUntil": "2034-02-02",
    "nft": {
      "tokenId": "1",
      "chain": "polygon-amoy",
      "contractAddress": "0x45c9597b5441289C134E554990cdb647f65df5FB"
    },
    "issuer": {
      "id": "did:polygon-amoy:0x1785A5DE9e0F06791393739De496a0a2c9ACA855"
    },
    "type": ["VerifiableCredential", "Course completion"],
    "validFrom": "2025-05-28T14:31:03.514Z",
    "@context": ["https://www.w3.org/ns/credentials/v2"],
    "proof": {
      "verificationMethod": "did:polygon-amoy:0x1785A5DE9e0F06791393739De496a0a2c9ACA855#evmAddress",
      "created": "2025-05-28T14:31:03.514Z",
      "proofPurpose": "assertionMethod",
      "type": "EthereumEip712Signature2021",
      "proofValue": "0x17f624a23b620de2867dbefbeb5214e5693a4b470897302f91f870383d4f5ee7754600d1fb72b73c926fed56aac20724ce87d49e0078e0b13f02734a199ceaa61b",
      "eip712": [Object]
    }
  }
}

6. Verify a Credential

To verify a credential’s validity:

verifyCredential.js

const apiKey = "YOUR_API_KEY";
const env = "staging"; // or "www"
const credentialId = "YOUR_CREDENTIAL_ID";

const url = `https://${env}.crossmint.com/api/v1-alpha1/credentials/verification/verify`;
const options = {
    method: "POST",
    headers: {
        "accept": "application/json",
        "content-type": "application/json",
        "x-api-key": apiKey,
    },
    body: JSON.stringify({
        // paste credential object here
        credential : {
            id: "urn:uuid:e6b3dc76-a337-437b-ac1b-3d330e66e1a6",
            ...
        }
    })
};

fetch(url, options)
    .then((res) => res.json())
    .then((json) => console.log(json))
    .catch((err) => console.error("error:" + err));

Example response

JSON

{ isValid: true }

7. Revoke a Credential (Optional)

If needed, you can revoke a credential:

revokeCredential.js

const apiKey = "YOUR_API_KEY";
const env = "staging"; // or "www"
const credentialId = "YOUR_CREDENTIAL_ID";

const url = `https://${env}.crossmint.com/api/v1-alpha1/credentials/${credentialId}`;
const options = {
    method: "DELETE",
    headers: {
        accept: "application/json",
        "x-api-key": apiKey,
    },
};

fetch(url, options)
    .then((res) => res.json())
    .then((json) => console.log(json))
    .catch((err) => console.error("error:" + err));

Example response

JSON

{
  "actionId": "15bfe43c-3d5d-4d03-9e20-6dbaf01f038f",
  "action": "nfts.delete",
  "status": "pending",
  "data": {
    "chain": "polygon-amoy",
    "collection": {
      "id": "a9e3016b-66f0-40ab-8d72-6546fddc7b72",
      "contractAddress": "0x45c9597b5441289C134E554990cdb647f65df5FB"
    },
    "token": { 
      "id": "6728f773-61af-4732-a34f-b5a50d8b9872", 
      "tokenId": "1" 
    }
  },
  "startedAt": "2025-05-28T16:53:11.000Z",
  "resource": "https://staging.crossmint.com/api/2022-06-09/collections/a9e3016b-66f0-40ab-8d72-6546fddc7b72/nfts/15bfe43c-3d5d-4d03-9e20-6dbaf01f038f"
}

Learn More

For more detailed information about Verifiable Credentials, please visit the dedicated Verifiable Credentials section which includes comprehensive guides on:

Create Credential Types

Learn how to define the structure of your credentials.

Create Credential Templates

Create reusable templates for your credentials.

Issue Credentials

Issue credentials to users.

Verify Credentials

Verify the authenticity of credentials.

Introduction

Wallets

Authentication

Tokenization (Minting)