Hi, you can use any of our Runtimes as opposed to Phaser; see here for more details:
Spine: Runtimes

To add to Luke's response, if you are looking at Phaser you are probably targeting browsers. You could use our spine-ts runtime instead of Phaser. spine-ts can render using HTML canvas or WebGL, without any game toolkit or 3rd party code. However, if you are building a game then you will likely need to implement other functionality needed for your game, such as mouse/keyboard input handling, drawing images besides your Spine skeletons, audio playback, etc. These things are needed by most games. A game toolkit like Phaser, Pixi.js, libgdx, Unity, etc provide a lot of functionality that most games need and may save you time.

If you just need to render a Spine skeleton, the Spine web player (which is part of spine-ts) makes that very easy, but again you may need to add other functionality you need as the Spine Runtimes don't provide all the functionality that a game toolkit provides.