Differences between GitHub Apps and OAuth Apps

Understanding the differences between GitHub Apps and OAuth apps will help you decide which type of app you want to create.

Who can install GitHub Apps and authorize OAuth Apps?

You can install GitHub Apps in your personal account or organizations you own. If you have admin permissions in a repository, you can install GitHub Apps on organization accounts. If a GitHub App is installed in a repository and requires organization permissions, the organization owner must approve the application.

By default, only organization owners can manage the settings of GitHub Apps in an organization. To allow additional users to manage GitHub Apps in an organization, an owner can grant them GitHub App manager permissions. See "GitHub App Managers" in the GitHub Help documentation to learn how to add and remove GitHub App managers in your organization.

By contrast, users authorize OAuth Apps, which gives the app the ability to act as the authenticated user. For example, you can authorize an OAuth App that finds all notifications for the authenticated user. You can always revoke permissions from an OAuth App.

GitHub Apps OAuth Apps
You must be an organization owner or have admin permissions in a repository to install a GitHub App on an organization. If a GitHub App is installed in a repository and requires organization permissions, the organization owner must approve the application. You can authorize an OAuth app to have access to resources.
You can install a GitHub App on your personal repository. You can authorize an OAuth app to have access to resources.
You must be an organization owner, personal repository owner, or have admin permissions in a repository to uninstall a GitHub App and remove its access. You can delete an OAuth access token to remove access.
You must be an organization owner or have admin permissions in a repository to request a GitHub App installation. If an organization application policy is active, any organization member can request to install an OAuth App on an organization. An organization owner must approve or deny the request.

What can GitHub Apps and OAuth Apps access?

Account owners can use a GitHub App in one account without granting access to another. For example, you can install a third-party build service on your employer's organization, but decide not to grant that build service access to repositories in your personal account. A GitHub App remains installed if the person who set it up leaves the organization.

An authorized OAuth App has access to all of the user's or organization owner's accessible resources.

GitHub Apps OAuth Apps
Installing a GitHub App grants the app access to a user or organization account's chosen repositories. Authorizing an OAuth App grants the app access to the user's accessible resources. For example, repositories they can access.
The installation token from a GitHub App loses access to resources if an admin removes repositories from the installation. An OAuth access token loses access to resources when the user loses access, such as when they lose write access to a repository.
Installation access tokens are limited to specified repositories with the permissions chosen by the creator of the app. An OAuth access token is limited via scopes.
GitHub Apps can request separate access to issues and pull requests without accessing the actual contents of the repository. OAuth Apps need to request the repo scope to get access to issues, pull requests, or anything owned by the repository.
GitHub Apps aren't subject to organization application policies. A GitHub App only has access to the repositories an organization owner has granted. If an organization application policy is active, only an organization owner can authorize the installation of an OAuth App. If installed, the OAuth App gains access to anything visible to the token the organization owner has within the approved organization.
A GitHub App receives a webhook event when an installation is changed or removed. This tells the app creator when they've received more or less access to an organization's resources. OAuth Apps can lose access to an organization or repository at any time based on the granting user's changing access. The OAuth App will not inform you when it loses access to a resource.

Token-based identification

Note: GitHub Apps can also use a user-based token. For more information, see "Identifying and authorizing users for GitHub Apps."

GitHub Apps OAuth Apps
A GitHub App can request an installation access token by using a private key with a JSON web token format out-of-band. An OAuth app can exchange a request token for an access token after a redirect via a web request.
An installation token identifies the app as the GitHub Apps bot, such as @jenkins-bot. An access token identifies the app as the user who granted the token to the app, such as @octocat.
Installation tokens expire after a predefined amount of time (currently 1 hour). OAuth tokens remain active until they're revoked by the customer.
GitHub Apps use the installation's minimum rate limit of 5,000 requests per hour. Organization installations with more than 20 users receive another 50 requests per hour for each user. Installations that have more than 20 repositories receive another 50 requests per hour for each repository. OAuth tokens use the user's rate limit of 5,000 requests per hour.
Rate limit increases can be granted both at the GitHub Apps level (affecting all installations) and at the individual installation level. Rate limit increases are granted per OAuth App. Every token granted to that OAuth App gets the increased limit.

Requesting permission levels for resources

Unlike OAuth apps, GitHub Apps have targeted permissions that allow them to request access only to what they need. For example, a Continuous Integration (CI) GitHub App can request read access to repository content and write access to the status API. Another GitHub App can have no read or write access to code but still have the ability to manage issues, labels, and milestones. OAuth Apps can't use granular permissions.

Access GitHub Apps (read or write permissions) OAuth Apps
For access to public repositories Public repository needs to be chosen during installation. public_repo scope.
For access to repository code/contents Repository contents repo scope.
For access to issues, labels, and milestones Issues repo scope.
For access to pull requests, labels, and milestones Pull requests repo scope.
For access to commit statuses (for CI builds) Commit statuses repo:status scope.
For access to deployments and deployment statuses Deployments repo_deployment scope.
To receive events via a webhook A GitHub App includes a webhook by default. write:repo_hook or write:org_hook scope.

Repository discovery

GitHub Apps OAuth Apps
GitHub Apps can look at /installation/repositories to see repositories the installation can access. OAuth Apps can look at /user/repos for a user view or /orgs/:org/repos for an organization view of accessible repositories.
GitHub Apps receive webhooks when repositories are added or removed from the installation. OAuth Apps create organization webhooks for notifications when a new repository is created within an organization.

Webhooks

GitHub Apps OAuth Apps
By default, GitHub Apps have a single webhook that receives the events they are configured to receive for every repository they have access to. OAuth Apps request the webhook scope to create a repository webhook for each repository they needs to receive events from.
GitHub Apps receive certain organization-level events with the organization member's permission. OAuth Apps request the organization webhook scope to create an organization webhook for each organization they need to receive organization-level events from.

Git access

GitHub Apps OAuth Apps
GitHub Apps ask for repository contents permission and use your installation token to authenticate via HTTP-based Git. OAuth Apps ask for write:public_key scope and create a deploy key via the API. You can then use that key to perform Git commands.
The token is used as the HTTP password. The token is used as the HTTP username.

Machine vs. bot accounts

Machine user accounts are OAuth-based user accounts that segregate automated systems using GitHub's user system.

Bot accounts are specific to GitHub Apps and are built into every GitHub App.

GitHub Apps OAuth Apps
GitHub App bots do not consume a GitHub Enterprise seat. A machine user account consumes a GitHub Enterprise seat.
Because a GitHub App bot is never granted a password, a customer can't sign into it directly. A machine user account is granted a username and password to be managed and secured by the customer.