Use VirusTotal to upload the file and scan it against dozens of antivirus engines.
There is no widely recognized or official application specifically named "Yaps209 sign apk." This name likely refers to a specific or a package name (like a build identifier) of an existing APK signing tool.
If you are looking for a reliable way to sign APK files on Android, What is "APK Signing"?
If you are looking for authentic, untouched apps, APK Mirror is a highly reputable source that verifies all signatures before publishing. Safety Checklist for Unknown APKs
Are you trying to that you developed, or are you trying to re-sign a modified app for personal use? apk-signer - Apps on Google Play
Be wary if the app asks for excessive permissions, like access to your contacts or SMS, that it doesn't need for signing files.
An APK must be before it can be installed on an Android device. This signature verifies the developer's identity and ensures the app hasn't been tampered with. Recommended & Safe Tools
If you have already downloaded "Yaps209" and want to check its safety: