PHP OAuth 2.0 Server VS OAuth 2.0 Client

For creating a PHP OAuth2 server take a look at https://oauth2.thephpleague.com/ it is not a complete server, but will do most of the work for you.

For the server side, I'll use the OAuth 2.0 server library. The implementation here is more complex, as there are many moving parts that need to be in place.

I looked at the phpleague oauth2-server and there, they say that a SPA (front end in angular or react) should use Authorization code grant and not password grant (it seems password grant is not recommended to use anymore).

Laravel Passport facilitates full OAuth2 server implementation for Laravel Apps in less time. Developing an OAuth2 server from scratch can be tedious and time-consuming, but Laravel Passport is a local OAuth 2 server for Laravel apps. The Laravel Passport package embodies routes, middleware, and database migrations to develop an authorization server that will return access tokens for giving access permission to server resources. It uses the League OAuth2 Server package as a dependency and has a straightforward, easy-to-learn, and easy-to-implement language structure.

Disclosure: I work for FusionAuth.

Depends on what you are looking for.

If you want a standalone auth server, you can use FusionAuth in docker/docker-compose: https://fusionauth.io/docs/v1/tech/installation-guide/docker

You can also package up a library; most major languages have one or more OAuth/OIDC libraries: https://github.com/doorkeeper-gem/doorkeeper for Ruby, https://spring.io/projects/spring-security for Spring/Java, https://oauth2.thephpleague.com/ for PHP, https://pypi.org/project/oauthlib/ for Python.

https://oauth.net/code/ has a further selection of libraries in a variety of languages.

I completely agree with this!! Sometimes there's too much hubris in OSS; classes made final, methods made private- because the author has made their mind up about how the library should work and be used. But sometimes it's not possible to imagine every use case. If software is extensible and someone breaks their app by extending your library and doing something wrong, that's their problem. Take a look at this for example: https://github.com/thephpleague/oauth2-server/issues/885 here the authors don't want to make it more extensible because some people might encode too many claims into their tokens and run into problems with header size. Ffs get off your high horse and let people use their own judgement !! /rant

https://github.com/thephpleague/oauth2-server is also good

Otherwise, if I need something larger, then I would go towards OAuth and than in particular OAuth2 from the PHP league. It provides a good framework to work with to implement authentication in your project. Setting up is a bit of work, but when it works, you don't need to look at it again.

League/oauth2-client has a lot of implementations

Have a look on this one https://oauth2-client.thephpleague.com/

In regards to oauth the phpleague packages are fairly popular. Again, the flow requires some redirect dancing so not something that can be (simply) just a single boolean-returning method on the PHP side. Additionally, oauth is a relatively weak standard (Especially where you want to verify identity) in which case platform specific actions/tweaks are needed hence why most use platform-specific oauth libraries. OIDC builds upon oauth to standardize the flow, including getting the identity, but it isn't supported by all platforms offering oauth.

For the client side, I'll be using the library league/oauth2-client.

"Login with Google/Facebook/Twitter/etc": That's called OAuth2 and quite easy to implement. This package is good OAuth2 client to start.

I'd recommend using a library - for Azure AD OAuth we've been using https://github.com/thephpleague/oauth2-client + https://github.com/thenetworg/oauth2-azure (see also https://oauth2-client.thephpleague.com/providers/thirdparty/ )

For Azure AD, I'd recommend the combination of https://github.com/thephpleague/oauth2-client for the authentication part (getting the token) and the Microsoft Graph SDK for then using the token to get information about the user https://github.com/microsoftgraph/msgraph-sdk-php

Here's a good example of that: https://github.com/thephpleague/oauth2-client/blob/master/.gitattributes