Can I file an RTI application on behalf of someone else, like a parent or friend?

An RTI application must be made in the applicant's own name - you cannot sign it for another person. But you can ask about any matter, including one that affects a family member, because the RTI Act does not require you to have a personal stake. The practical limit is Section 8(1)(j), which since 13 November 2025 exempts information which relates to personal information: another person’s personal details can be withheld, and the public-interest tests to plead are Section 8(2) and, for third-party records, the proviso to Section 11(1). So the cleanest route is for the concerned person to be the named applicant (you can still do all the work), or for you to frame questions around records and processes rather than another person's private details.