You can use the point and click interface below to create encoded polylines for display by the Google Maps API. The parameters verySmall, numLevels, and zoomFactor are explained on my main encoding page. Most of the rest is pretty self-explanatory.
This page is mainly for experimentation. Polyline encoding is useful primarily when the path has several thousand vertices - more than you want to enter by hand. For this reason, "path update" is set to "last five" by default so that the ordinary polyline, which is updated with each click, doesn't slow things down too much as the path gets long.
If you create an encoded polyline at a high zoom level, you might notice the path shift slightly when you finish it. This is due to the fact that the encoding algorithm retains only five digits of accuracy from the input lat/lng pairs. The effect is slightly noticeable at zoom level 17. It is quite noticeable at zoom level 19, the highest zoom level of satellite images in many major cities.