Simon Willison builds a Bluesky bot detector with Opus 5.5
What happened
On 28 September 2026, Simon Willison announced a Bluesky reply-bot detection tool written with Opus 5.5. It can analyse any Bluesky account for signs of automated replies. According to Willison, signals include replying within seconds of another account posting, never publishing original content or image links and only replying to users with large followings, and including question marks in replies. He also noted that Bluesky still offers a free API, making this kind of investigation more feasible than on Twitter. The tool can now analyse any Bluesky account, with developments centred on its release and explanation of its features.
Written by AI from the reports · updated 2 d ago
Timeline
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- Simon WillisonBluesky reply bot checker
Simon Willison used Opus 5.5 to build a tool analysing any Bluesky account for automated reply-bot signals. These include replying within seconds, never posting original content or image links and replying only to high-follower accounts, and using question marks in replies. Bluesky's free API makes such investigations more feasible than on Twitter.
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