FlexTween is a lightweighted and extensible tweening library.
Besides basic features(duration, delay, easing curves, looping), it also has convenient features like timescale ignoring, auto-start, inversing, custom curves, and special features like method chaining, tween event callbacks, pausing and resuming, parallel and sequential compounds, step tweeners etc.
With FlexTween, you're able to tween almost everything in a single line of code or by components.
This library is well documented for API referencing. For beginners and intermediates, you also can learn design patterns from it. Core classes are abstracted, ready for extending. Predefined tweeners have almost covered everything from transform tweening to UI tweening. By tweeking with the tween events, you can control every step of the workflow.

Introduction:

Core(Scripting Backend) Features
- Method chaining: one-line setup
- Resumable: pause and resume tweeners
- Custom easing curves: draw custom curves
- Steps: multiple tweening values instead of just from and to
- Compounds: merge tweeners with +(sequential) and *(parallel)
- Events: initialize, begin, start, update and end
- Extensible: abstract and generic core classes
- Documented: all exposed members are well documented

Component(Editor) Features
- Test: control tweeners in editor
- Friendly: properties are displayed properly for customizing
- Minimized: unnecessary properties are automatically hidden
- Interactive: Some components accept drag and drop

Additional Components
- Ripple Effect: google's material like ripple effect
- Mask Effect: make scene transition easily
- Invoke: tween component members(fields, properties and methods)
- Material: tween renderer's material shader properties
- Alignment: tween ui relative alignments
- Sprites and Textures: tween animations like sprite sheets and texture offsets
- More: Progress, Fill, Volume, UI Size, Alpha

Website:
flexframework.net