# Simon Willison builds a checker for Bluesky reply bots

> Simon Willison has made a tool that checks Bluesky profiles for signs of automated reply bots. It looks for patterns such as rapid-fire replies and accounts that only respond to other users.

Oossa · 2026-09-29 · https://oossa.com/en/simon-willison-builds-a-checker-for-bluesky-reply-bots

The tool examines a Bluesky profile for clues that an account may be a reply bot. It checks whether replies arrive within seconds of one another, and whether an account mainly replies to posts from more popular users instead of sharing its own content, images or links.

Willison says he used Opus 5.5 to build it. He says Bluesky’s public API makes it easier to investigate accounts than Twitter’s, where reply bots have also been a problem. The checker also looks for question marks, since Willison says some bots try to draw people into answering questions no person actually asked.

## The facts

- Published by Simon Willison on September 27, 2026.
- The checker looks for reply timing, original posts, images, links and question marks.

## Why it matters

The tool gives Bluesky users a way to spot patterns that may help distinguish automated replies from genuine conversation.

## Sources & references

1. [Bluesky reply bot checker](https://simonwillison.net/2026/Sep/27/bluesky-bot-check/) – Simon Willison, 2026-09-27

Last updated: 2026-09-29