Set up Multiple Github accounts on Mac

Objective

Set up two GitHub identities on the same Mac — one as your global default, and another isolated per‑repository using SSH aliases — so you can switch accounts seamlessly without conflicts:

• One GitHub account configured globally (~/.gitconfig).
• Another GitHub account configured per-repository or via SSH alias, so they don’t conflict.

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Step 1: Check your current setup

git config --global user.name
git config --global user.email
cat ~/.ssh/config  # optional

That’s your primary (default) GitHub identity.

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Step 2: Create a new SSH key for the second account

For example, if your new GitHub account is personal, do:

ssh-keygen -t ed25519 -C "your_other_email@example.com" -f ~/.ssh/id_ed25519_personal

When asked for a passphrase, you can leave it empty or use one (recommended for security).

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Step 3: Add that key to your SSH agent

eval "$(ssh-agent -s)"
ssh-add --apple-use-keychain ~/.ssh/id_ed25519_personal

This stores the key in macOS Keychain.

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Step 4: Add the public key to your other GitHub account

Copy and paste it into GitHub → Settings → SSH and GPG keys → New SSH key

cat ~/.ssh/id_ed25519_personal.pub

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Step 5: Create SSH config aliases

Edit (or create) your ~/.ssh/config file:

# Default (work) GitHub
Host github.com
  HostName github.com
  User git
  IdentityFile ~/.ssh/id_ed25519
  AddKeysToAgent yes
  UseKeychain yes

# Personal GitHub
Host github-personal
  HostName github.com
  User git
  IdentityFile ~/.ssh/id_ed25519_personal
  AddKeysToAgent yes
  UseKeychain yes

This lets you use github-personal as a fake hostname for the second identity.

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Step 6: Clone repositories using the alias

For the personal account:

git clone git@github-personal:username/repo.git

For the default/work one:

git clone git@github.com:workuser/repo.git

Each uses its own key.

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Step 7: Set per-repo identity (optional but recommended)

Inside the personal repo:

cd ~/code/personal-repo
git config user.name "Your Personal Name"
git config user.email "your_other_email@example.com"

This ensures commits are attributed to the right GitHub account.