ePnR
ePnR is an IC block standard cell placement & routing tool
..., by simulated annealing is available. Routing consists of channel routing as first step. If un-routed connections are left, Maze routing can (optionally) be applied. ePnR does not guarantee completely finished routing. However, un-routed connections will be left with rubberband connections and marked start and end points for subsequent manual routing using a third party layout editor. ePnR outputs in CIF 2.0 and GDS stream format readable by e.g. the free KLayout editor.