Character classification by type
I strongly recommend an online dictionary 汉典.
It may be the most professional online Chinese dictionary even for native speakers.

For every entry, you can refer to the section "字形分析" to know the classification of the character.

For example, the character 强 is classified as compound ideographs (会意), which is shown in the picture:

The dictionary also collect contents from 《康熙字典》 and 《说文解字》, you can also learn the origin and example sentences of each entry.