Update: OCI certifications are now free until February 28, 2022

On September 8, 2021 Oracle announced that they are now offering free Oracle Cloud Infrastructure (OCI) digital training and, for a limited time, free OCI certification worldwide – including the entire expert-created OCI learning curriculum from beginner to advanced, and for various role types.

While the training will continue to be available for free, the certification free offer was originally meant to be completed December 31, 2021.

NOW, the free offer for the certification is extended to February 28, 2022.

Oracle Cloud Infrastructure (OCI) helps thousands of companies and millions of users run their entire application portfolio and mission critical workloads, in the cloud. OCI is one of the fastest growing cloud platforms, increasing demand for OCI expertise across the globe. Advance and future-proof your career by learning OCI for free with our expert-created training and globally recognized certification program.

To make sure that you are getting the most value as possible out of the training content, they also offer access to hands-on labs to practice what you are learning.
There are two options to access the hands-on-labs. 

1. First, to access all labs associated with all courses, you need to set up an Oracle Cloud Free Tier account.  This can be done quickly; however, it will require you to enter your credit card number, which will not be charged and is only required for any future purchases which you will have the ability to opt-out of. 
2. For those of you who do not want to open an Oracle Cloud Free Tier account, we offer quick and easy access to labs associated with the OCI Foundations course.  You can use this free environment to practice creating virtual machines and autonomous databases. Additionally, this free environment does not require you to install any development tools on your local machine. 

Oracle Certification Exams include:

Check https://education.oracle.com/oracle-oci-certification !
You need to act fast though!

Note: See here https://blogs.oracle.com/oracleuniversity/post/hands-on-labs-oci-training how to activate your free OCI Training Environment.