title: Curl: Invalid JSON
body: <p>I'm trying to use the sendgrid curl for adding a new contact.</p>
  
  <p>This is what I got</p>
  
  <pre><code>curl --request PUT \
    --url https://api.sendgrid.com/v3/marketing/contacts \
    --header 'authorization: Bearer myAPIKEY' \
    --data '{"contacts":[{"email":"mymail@icloud.com","first_name":"Karel","last_name":"Deb"}]}’
  </code></pre>
  
  <p>But it returns this</p>
  
  <pre><code>{
    "errors": [
      {
        "field": "",
        "message": "invalid JSON"
      }
    ]
  }
  </code></pre>
  
  <p>What am I doing wrong?</p>
  
  <p>Thank you!</p>