How to check if a software is safe or not?

Hey there, I'm curious about something. When it comes to software, especially in the realm of cryptocurrency and finance, how do you actually go about checking if a particular program or application is SAFE to use? Is there a specific set of criteria or tools that experts in the field rely on to ensure that their data and transactions are protected? I'm particularly interested in knowing how to spot potential red flags or vulnerabilities that might compromise security. Any insights you can offer would be greatly appreciated!