This is an "experiment," Twitter says, and it's not clear if or when the Lite app will be available in other countries.

It won't be surprising if Twitter Lite spreads to many areas, though. Twitter is struggling to add new users, and a lightweight app would help it reach audiences that can't even consider using the regular app. In the Philippines, for example, prepaid use is much more common than subscribing to a regular data plan. Basic Facebook access is free thanks to carrier deals, but that's limited when many can't load more than the headline for a shared article. Twitter would not only get its foot in the door, it could serve as a viable alternative to Facbook given its emphasis on short, data-friendly text updates. And when countries like India have similarly limited access in rural areas, that's a lot of potential new users.

Mariella Moon contributed to this report.