The "gold standard" for U.S. users, providing a permanent secondary number that integrates with your existing Google account.
Provides a 14-day free trial to test their platform and send messages.
While it's unclear if you're looking for a way to send messages without a credit card or a tool to generate "fake" text image, there are several ways to do both.
If you need texting for a business, several platforms offer free trials with no credit card commitment:
Allows you to test business messaging with free credit and no credit card needed. Text Content Generators
Many services allow you to send real SMS or make calls over Wi-Fi without ever asking for payment information.