If you're looking for anime similar to Infinite Stratos, you might like these titles. All recommendations are made by Anime-Planet users like you!
When deadly asteroids threaten Earth, an elite team of interceptors--the Meteor Sweepers--are formed. Now, rookie pilot Honjou Mikaze and her three friends are caught up in tumultuous events that may expose a sinister conspiracy and put the fate of the world into the hands of a few young girls...
Teenage girls, high tech weapons, save the world... Both of these anime have a lot in common. Stratos 4 has a little more realistic premise (aliens notwithstanding), shoot down meteor fragments to save the world.
Infinite stratos is a bit more science fictiony, with personal mechs, and what might as well be magic. Both start off fairly similar. Protaganists going to school, learning to operate the high tech equipment, deal with personal stuff, things like that.
IS is a little different in that there is a romance/harem thread to go along with it, Stratos 4 lacks both the Harem completely, and no real romance to speak of.
While different, if you like to see Teenage Girls (and a guy in IS) fly planes and mechs and save the world, if you like one, I highly recommend checking out the other.
Since so few women are naturally born with the ability to become Pandoras and fight the extra dimensional aliens known as Nova, a program is approved by the Chevalier organization to allow any female to artificially become such a warrior. In order to test this new generation of E-Pandora, small groups of the highest ranked cadets from various Pandora academies around the globe are sent to Alaska in order to gauge the project's progress. Among those sent are Satellizer, Rana, and Kazuya since they display a skill level far above their position. It is not merely their combat prowess that is tested however, when the Evolution Pandora project does not go as expected.
Both these shows are fanservice vehicles for their cast of well endowed females. Both shows involve the girls all fighting, but Infinite Stratos uses mechs to fight.
Freezing is more explicit with actual nudity. If you're looking for some ecchi fanservice with minimal plot then these are the shows for you.
Sousuke Sagara is far from the average high school student - not only is he highly trained in military tactics, he puts his knowledge to use in every single applicable situation (and even those nonapplicable ones.) So, when confronted with high school, he tends to turn average high school experiences into off-the-wall adventures. Love letters become terrorist threats and field trips become commando operations; his survival depends on the watchful eye of his best friend and classmate, Kaname. Together, they may just make it out of high school alive...
Invertia… an unprecedented disaster that struck the world during the 20th century. Because of this disaster, numerous cities around the world were destroyed. However, within the meteor, an unknown element called mana was discovered, which allowed human technology to make rapid strides. This also gave rise to a new species of human born with unique skills – the Star Pulse Generation. The setting for the world’s greatest comprehensive battle spectacle, the Festas, is an academy city above the water surrounded by six academies called Rikka also commonly known as Asterisk.
I can say with confidence that these two anime are practically the same thing. Not to mention that the characters look alike due to the fact the the original novel artist for both anime were the same person. The only difference between the two is the absence of mecha in Asterisk, other than that, they are very alike.