Add Postman Echo (#2123)

README.md

@@ -381,6 +381,7 @@ API | Description | Auth | HTTPS | CORS |
 | [Cloudmersive Validate](https://cloudmersive.com/validate-api) | Validate email addresses, phone numbers, VAT numbers and domain names | `apiKey` | Yes | Yes |
 | [EVA](https://eva.pingutil.com/) | Validate email addresses | No | Yes | Yes |
 | [Lob.com](https://lob.com/) | US Address Verification | `apiKey` | Yes | Unknown |
+| [Postman Echo](https://www.postman-echo.com) | Test api server to receive and return value from HTTP method | No | Yes | Unknown |
 | [PurgoMalum](http://www.purgomalum.com) | Content validator against profanity & obscenity | No | No | Unknown |
 | [US Autocomplete](https://smartystreets.com/docs/cloud/us-autocomplete-api) | Enter address data quickly with real-time address suggestions | `apiKey` | Yes | Yes |
 | [US Extract](https://smartystreets.com/products/apis/us-extract-api) | Extract postal addresses from any text including emails | `apiKey` | Yes | Yes |