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Free Libraries Worth Knowing

Popular free tools and packages that save you from building everything yourself, plus how to install them safely.

Libraries are like power tools. You could build a bookshelf with a hand saw, but a drill someone else already built saves hours. The trick is knowing which tools are worth having, and not buying ten drills that all do the same thing.

Before you install anything

Check that it's still updated and works with your Unity version, read its licence (everything below is free to use in commercial games at the time of writing, but licences can change), and use version control so you can undo an install. Add one library at a time.

How to install packages

Where it's from	How
Unity Registry (Unity's own)	Window > Package Manager > Unity Registry > find it > Install.
Asset Store	Click Add to My Assets on the website, then in Package Manager open My Assets > Download > Import.
GitHub	Package Manager > + > Install package from git URL, and paste the URL from the project's README. (Needs Git installed.)
OpenUPM	A free catalogue of open-source packages. See openupm.com for the steps.

Free from Unity (start here)

These are made by Unity, free, and install from the Unity Registry.

Package	What it saves you from
Cinemachine	Writing camera code. Follow cams, orbit cams, screen shake, cutscene cameras, all without scripts.
Input System	Hard-coding keys. Keyboard, gamepad and touch in one place, with rebinding. See the tutorial.
ProBuilder	Waiting on 3D art. Build and test level layouts directly in the editor.
Splines	Writing curve maths. Draw paths for rails, roads and moving platforms. (See Bezier Curves for how they work.)
Timeline	Scripting cutscenes. Line up animations, sounds and camera moves on a timeline.
Newtonsoft Json (`com.unity.nuget.newtonsoft-json`)	JsonUtility's limits. Saves dictionaries, properties and more. See Saving & Loading.
AI Navigation	Writing pathfinding. See NavMesh in Depth.
Localization	Hand-rolling translations of text and assets.

Animation & game feel

Library	What it does	Get it
DOTween	Move, scale, fade and shake anything in one line. The most widely used tween library. (A paid Pro version adds extras.)	Asset Store · our page
PrimeTween	A newer tween library, designed to create no garbage. Similar one-line style.	Asset Store · GitHub

Pick one tween library per project.

Nicer Inspector

Library	What it does	Get it
NaughtyAttributes	Adds attributes like `[Button]` (a clickable button in the Inspector that runs a method), `[ShowIf]`, `[ReadOnly]` and dropdowns.	GitHub · Asset Store
Tri-Inspector	Similar idea with groups, tabs and validation. A free alternative to the paid Odin Inspector.	GitHub

using NaughtyAttributes;
using UnityEngine;

public class Spawner : MonoBehaviour
{
    [SerializeField] private bool useTimer;
    [SerializeField, ShowIf("useTimer")] private float interval = 2f; // only shown when useTimer is ticked

    [Button] // a "Spawn Now" button appears in the Inspector
    private void SpawnNow() { Debug.Log("Spawned!"); }
}

Code helpers

Library	What it does	Get it
UniTask	Faster, garbage-free `async/await` for Unity, with helpers like `UniTask.Delay`. Learn async & await first; Unity 6's built-in `Awaitable` covers the basics.	GitHub
VContainer	"Dependency injection": hands each script what it needs instead of using singletons. Great for bigger projects; skip it for your first game.	GitHub

Debugging

Library	What it does	Get it
Graphy	An on-screen FPS, memory and audio monitor. Great for testing on phones.	GitHub · Asset Store
In-game Debug Console	See the Console (logs and errors) inside a build, on any device.	GitHub · Asset Store

Dialogue & story

Library	What it does	Get it
Yarn Spinner	Write branching conversations in a simple script format. Used in games like Night in the Woods.	GitHub
Ink	inkle's narrative scripting language (80 Days), with a Unity plugin.	GitHub

Multiplayer

Library	Notes
Netcode for GameObjects	Unity's own, in the Unity Registry.
Mirror	Open source, large community, lots of tutorials. GitHub
FishNet	Open source, many built-in features. GitHub

Multiplayer is hard

No library makes it easy. Finish a small single-player game first.

Free art and sound

Site	What you get
Kenney	Thousands of 2D, 3D, UI and audio assets in a matching style. Public domain (CC0).
Quaternius	Low-poly 3D models and characters. CC0.
Poly Haven	Textures, HDRI skies and models. CC0.
Mixamo	Free character animations (needs an Adobe account).

CC0 means you can use it for anything without credit, though crediting is a nice thing to do. Always check the licence of each asset you download.

Should I use a library or build it myself?

Use a library when…	Build it yourself when…
It's a hard, solved problem (cameras, tweening, networking)	It's small and specific to your game
You want to finish the game	You want to learn how it works (see Building Your Own Systems)
It's popular and actively maintained	The library is abandoned or much bigger than what you need

Common Mistakes

Installing ten libraries on day one and never learning the basics.
Two libraries that do the same job (two tween libraries, two inspector libraries).
Downloading "free" paid assets from random websites. They can contain malware and are illegal to ship.
Not reading the README, then wondering why the git URL install fails.