Align UV is a simple to for aligning UV faces to XY axis and same size.
Version 3.0.0 is the complete redesign of the tool. It used a new engine.

You can use this tool in UV Editor , in Face mode of Edge mode.
Select faces in UV, then run the tool (Right Click inside the UV Editor, select Align UV at the bottom of Context menu).

In Edge mode, you can select a sequence of edges, then run the tool, and check the option "Align Faces by Edge"

Align UV support Edge-Length scale too !

Instead of square grids, it produce more original like shape.

You can also straighten an edge-line by fixing the location of Start and End points.

You can also straighten "Only Selected Edges" without touching other faces.

The most powerful function of Align UV : Pinned UV support

You can select vertices then use blender's UV Menu > Pin to "Pin" the location of specified verts, then run Align UV again. Repeated Pinning is really powerful to fine-tune your UV layout.

As you can see above, I pinned the "Left hand side edges", then select right hand sides edges and run Align UV.

In blender 5.0 or above, Align UV works on both Live Sync mode On and Off.

Usage

Go to UV Editor in Blender, switch to Face or Edge mode,

Select Faces, right click inside the viewport, then select Align UV at the bottom of the pop up Context Menu.

Or, you can select Edges, right click inside the viewport, then select Align UV at the bottom of the pop up Context Menu.

Updates

Version 4.0.0

• Added support for Blender 5.0
• Added support for the new UV Sync mode on Blender 5.0

Version 3.3.1

• Added the option to Pin the vertices after aligning (edge mode only)

Version 3.3.0

• Added the support of Pinned UV of blender. If vertices are pinned in UV editor, Align UV will not move it.

Version 3.2.0, 3.2.1

• Added the option "Global Axis". When this option is OFF and using Edges-line selection, the start and end points positions will be fixed, only the inner points are moved.

Version 3.1.0

• Added option for "Edge-Length Scale" ! It respect the original edges scale instead of all squares.

Version 3.0.0, 3.0.1, 3.0.2

• Rewrite the tool and used a new algorithm. It improved the quality and speed. Single tool work for both edges and faces aligning.

It is a free addon !

Hope that you like it : )

Kushiro

https://x.com/kushirosea