Expo: Does each user working on/building the app apk need a separate Keystore or use the same one?

Question

It's my first time building an expo app and I'm just now getting to the build/publish process where Expo asks about generating or uploading a Keystore. My coworker has built and published the app once already so my question is, do I need to use the same Keystore that was generated when he built it, or do I generate another one? Are Keystores app specific or user specific?

Answer 1

This is the link where you can get detailed information.

My coworker has built and published the app once already so my question is, do I need to use the same Keystore that was generated when he built it?

Answer is : Yes, you need to use same keystore as app is already published in playstore. otherwise you are not able to update the current app in playstore.

Answer 2

In case of KeyStore as the name suggests it is a store of keys. KeyStore is for one developer and using encryption for his works, may be several apps. If he trusts you the simple way is to give you the Keystore and the passwords for all the required apps.

There can be more than one private keys in one Keystore and securely he may decide not to give you!. So what you real need is the private key for that particular app, you may not need the whole Keystore from the other coworker developer. So by securing your apps you are not advised to give the whole keystore and passwords to another person may be if it is very worth it, You can check this from official sources advice in Android Studio Signing Your App and Training on Keystore.

HERE IS WHAT YOU HAVE TO DO
You need to tell your coworker to export the key for that particular app so you can take/import it to your own Keystore. Check the answer to a similar question here where using the command line is like:

keytool -importkeystore -srckeystore keystore.jks -destkeystore keystore.p12 -deststoretype PKCS12 -srcalias ALIAS -deststorepass PASS -destkeypass PASS

And also you can consider using Keystore Explorer Tool to do that to do the export and related stuffs.
But you should also consider using Google Play App Signing as explained in that link, it may simplify your management for apps also and secure the management without using your personal Keystores.

When you use Google Play App Signing, if you lose your upload key, or if it is compromised, you can contact Google to revoke your old upload key and generate a new one. Because your app signing key is secured by Google, you can continue to upload new versions of your app as updates to the original app, even if you change upload keys.
But if you and your coworker you do similar projects and team member and trust each other. The easiest way is to give you the Keystore and necessary Passwords.