Show HN: I built an interactive HN Simulator
Mood
excited
Sentiment
positive
Category
startup_launch
Key topics
Hacker News
Simulator
Llms
Node
Express
Postgres
Just for fun, I built an interactive Hacker News Simulator.
You can submit text posts and links, just like the real HN. But on HN Simulator, all of the comments are generated by LLMs + generate instantly.
The best way to use it (IMHO) is to submit a text post or a curl-able URL here: https://news.ysimulator.run/submit. You don't need an account to post.
When you do that, various prompts will be built from a library of commenter archetypes, moods, and shapes. The AI commenters will actually respond to your text post and/or submitted link.
I really wanted it to feel real, and I think the project mostly delivers on that. When I was developing it, I kept getting confused between which tab was the "real" HN and which was the simulator, and accidentally submitted some junk to HN. (Sorry dang and team – I did clean up after myself).
The app itself is built with Node + Express + Postgres, and all of the inference runs on Replicate.
Speaking of Replicate, they generously loaded me up with some free credits for the inference – so shoutout to the team there.
The most technically interesting part of the app is how the comments work. You can read more about it here, as well as explore all of the available archetypes, moods, and shapes that get combined into prompts: https://news.ysimulator.run/comments.html
I hope you all have as much fun playing with it as I did making it!
Discussion Activity
Active discussionFirst comment
2h
Peak period
20
Hour 7
Avg / period
13.6
Based on 122 loaded comments
Key moments
- 01Story posted
Nov 24, 2025 at 12:52 PM EST
11h ago
Step 01 - 02First comment
Nov 24, 2025 at 3:04 PM EST
2h after posting
Step 02 - 03Peak activity
20 comments in Hour 7
Hottest window of the conversation
Step 03 - 04Latest activity
Nov 24, 2025 at 11:50 PM EST
12m ago
Step 04
Generating AI Summary...
Analyzing up to 500 comments to identify key contributors and discussion patterns
Discussion hasn't started yet.
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