This one is pretty good, however, you have to tweak the settings to get it to work optimally for use within Construct 2:
texturepacker.com
Steps to use it:
Drag in the image files to the program, and after that, use the following settings:
Texture format: png
Image format: RGBA8888
Dithering: NearestNeighbor
Autosize: Checked
Allow free sizes: checked
Scale mode: Smooth
AutoSD: Unchecked
Algorithm: Basic
Sort by: Name
Order: Ascending
Border padding: 0
Shape padding: 0
Inner padding: 0
Extrude: 0
Reduce border artifacts: unchecked
Allow rotation: unchecked
Trim: unchecked
Crop: unchecked
Shape outlines: unchecked
Enable auto alias: unchecked
Heuristic mask: unchecked
Premultiply alpha: unchecked
Flip PVR: unchecked
Then do File -> Export Image
and you're all done.
Hope that helps,
-- cacotigon