AstroGuard

Inspiration

While scrolling around reddit for recommendations on dashcams, there oftentimes were many bot users that recommended no-name dash cams that were completely unknown and didn't have good reviews anywhere else. With this, it was very obvious that these bots were just trying to push their own agenda without any actual recommendations in mind. In the hopes of being more conscious of these bot users, AstroGuard was born.

What it does

AstroGuard is a browser extension that scans Reddit threads being browsed by users. This extension identifies the likelihood of each user in the thread of being a bot or not human, and allows users to avoid potential bot posts in the thread.

How we built it

AstroGuard uses a two tier architecture designed to be both accurate and cost efficient. The first tier uses combined heuristics with over 20 signals that can be evaluated with no API costs. This includes age to karma ratio, comment similarity, and generated content tells. The second tier uses Gemini 2.5 Flash, where we send up to 50 sampled comments from a user and have Gemini evaluate the bot likelihood through numerous prompts.

Challenges we ran into

A major challenge that we ran into was Reddit rate limiting unauthenticated access to 10 requests per minute. In order to solve this, we decided to implement an exponential backoff system in order to not overload the queue. Another challenge we face throughout the entire hackathon was score calibration, which we made many multipliers in order to make as accurate as possible.

Accomplishments that we're proud of

We are proud of the zero backend infrastructure as the extension is entirely client sided, making it respect your privacy. We are also proud of our insights dashboard as it shows meaningful aggregate info across subreddits that the user visited.

What we learned

We learned that bot detection is as much art as science, where the signal weightings and tuning thresholds require constant iteration. We also learned how to develop Chrome extensions with Manifest V3 has constrains around persistence and lifecycle management, which shaped our architecture.

What's next for AstroGuard

We want to be able to apply this to other social media as well, such as twitter, threads, etc. allowing for users to block botted content. We also want to be able to collect this data on subreddits in order to expose astroturfing trends on reddit.