Not OSSP is a Chrome add-on developed by kz26 that serves to alert users within the One Sentence Startup Pitches (OSSP) Facebook group if their posts exceed one sentence. It aims to maintain the group's focus on concise startup pitches by providing warnings for posts that deviate from the one-sentence format.

The add-on functions by detecting posts in the OSSP group that are longer than one sentence, ensuring that the content aligns with the group's intended purpose of concise startup pitches. Not OSSP enhances the user experience by promoting brevity and clarity in posts, helping members adhere to the group's guidelines effectively.