If you're looking for a way to create custom birthday messages using AI and celebrity voices, SendFame is a great choice. The service lets you create custom, realistic video messages and music from a variety of celebrities like Elon Musk, Donald Trump and Taylor Swift. You can pick a celebrity, write out what you want to say, and the AI will write the script, pick the voice and create the video. It's good for birthday wishes, but also other occasions.
Another option is PlayHT, an AI text-to-speech service with more than 600 realistic AI voices. It works in multiple languages and accents, and you can customize pronunciations and voice inflections. It's a general-purpose service that can be used for video voiceovers, audio publishing and more, so it's good for custom birthday messages.
If you want to concentrate on music, Lalals is an all-purpose music creation service that uses AI to transform and improve audio tracks. It's got tools to change your voice and to generate original songs using celebrity voices, so it's a good choice for custom birthday songs. The service can handle a variety of genres and languages, and you can use it for commercial purposes with a paid subscription.