Intel / article

Bluesky reply bot checker

Source: simonwillison.net
Date: Published Sep 27, 2026

Context

Simon Willison's Bluesky reply bot checker makes suspicious posting patterns inspectable. It examines an account's recent posts for signals such as how quickly replies follow other posts, how uniform the replies are, and who receives them, then shows each signal, threshold and piece of evidence so a person can check the reasoning.

Willison's description also highlights accounts that never post their own content but consistently reply to higher-follower users. The value is helping someone investigate why an account looks automated. The tool's own page says these are patterns, not proof, so its output is evidence to examine before making a judgment about an account.

Key takeaways · AI-distilled

Simon Willison had Opus 5.5 vibe code a checker that examines any Bluesky profile for signs of being a reply bot, possible because Bluesky, unlike Twitter, still offers a freely available and useful API.
The tool flags accounts that post replies within seconds of their other posts, and accounts that never post their own content, images or links but consistently reply to messages from higher-follower users.
It also weighs question marks, targeting bots that bait people into answering questions no human actually asked.

Read the source simonwillison.net