ChatGPT kept telling users Soundslice had a feature it didn't. The founder gave up and built it.
- Date
- Jul 2025
- Tools involved
- Impact
- Confused users signed up expecting a nonexistent ASCII tab importer; Soundslice built the feature to make ChatGPT's false claim true
- Root cause
- ChatGPT hallucinated a Soundslice ASCII tablature import feature and repeatedly directed real users to it
What happened
In July 2025, Soundslice founder Adrian Holovaty noticed something strange in his sheet-music app's error logs: users were uploading images of ChatGPT conversations containing ASCII guitar tablature. Investigating, he found that ChatGPT was routinely telling people that Soundslice could import ASCII tab and play it back as audio, and was instructing them to create a Soundslice account and upload their ChatGPT session to hear the music.
Soundslice had no such feature. ChatGPT had hallucinated it, and the false claim was driving real users to sign up expecting functionality that did not exist, damaging their first impression of the product through no fault of Soundslice's own.
Rather than just posting a disclaimer, Holovaty and his team decided to build a bespoke ASCII-tab importer so the hallucinated capability would actually work. He publicly described feeling conflicted about it: happy to ship a useful tool, but uneasy about "developing features in response to misinformation," and he called it possibly the first case of a company building a feature because ChatGPT wrongly insisted it existed.
The story was covered by TechCrunch and 404 Media alongside Holovaty's own blog post. It is a lower-stakes entry than most on this site, but a widely cited one, because it shows AI hallucinations reshaping a real product's roadmap and its users' expectations without anyone asking for either.
Impact
No data was lost and no dollar figure was reported; the damage here was subtler. A steady stream of users arrived at Soundslice expecting a feature that did not exist, hit a wall, and formed their first impression of the product from an AI's invention. The founder's team then spent real engineering time building an ASCII-tab importer that was never on their roadmap, effectively taking a feature request from a language model's imagination. Holovaty called it possibly the first case of a company shipping a feature because ChatGPT wrongly insisted it existed, which is exactly the kind of first nobody plans for.
Root cause
ChatGPT asserted a specific, plausible-sounding capability, that Soundslice could import ASCII guitar tab and play it as audio, with the confidence it applies to everything, and it did so repeatedly across many user conversations. There was no mechanism for Soundslice to correct the model, and users had no reason to doubt detailed instructions that included creating an account and uploading their session. The hallucination only surfaced because the resulting uploads landed in Soundslice's error logs, where someone was paying attention.
How to not be this entry
- Watch your logs for traffic patterns you did not design for. Soundslice caught this because ChatGPT screenshots started showing up in error logs and someone asked why.
- Verify a feature exists in the vendor's own documentation before you build a workflow, an integration, or a signup on an AI's description of a product. The model will describe nonexistent features with the same confidence as real ones.
- Treat confident AI claims about third-party capabilities the way you treat AI-suggested package names: as unverified output that needs a source check first. Read the fix guide: Slopsquatting: the AI hallucinated an npm package and an attacker registered it
- Remember that the model will not flag its own guesses, and it will not push back on yours either. Read the fix guide: Claude Code Says 'You're Absolutely Right!' and Keeps Applying the Same Broken Fix
Tools that actually fix this
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Try Snyk →Frequently asked questions
Why did Soundslice build an ASCII tab importer?
Soundslice built its ASCII tablature importer because ChatGPT was repeatedly and falsely telling users the app already had one, driving confused signups from people expecting to upload ASCII guitar tab and hear it played back. Rather than post a disclaimer, founder Adrian Holovaty and his team built the feature in July 2025 so the hallucinated capability would actually work.
How did Soundslice discover ChatGPT was hallucinating a feature?
Founder Adrian Holovaty noticed users uploading images of ChatGPT conversations containing ASCII guitar tablature in Soundslice's error logs. Investigating the odd uploads, he found ChatGPT was routinely telling people Soundslice could import ASCII tab and play it back as audio, and was instructing them to create an account and upload their ChatGPT session to hear the music.
What did ChatGPT falsely claim Soundslice could do?
ChatGPT told users that Soundslice, a sheet-music app, could import ASCII guitar tablature and play it back as audio, and it directed them to create a Soundslice account and upload their ChatGPT session to hear the result. Soundslice had no such feature at the time; ChatGPT had hallucinated it entirely.
Was Soundslice the first company to build a feature because of an AI hallucination?
Founder Adrian Holovaty publicly called it possibly the first case of a company building a feature because ChatGPT wrongly insisted it existed. He also described feeling conflicted about it, happy to ship a useful tool but uneasy about developing features in response to misinformation. The episode was covered by TechCrunch and 404 Media as a notable example of hallucinations reshaping real products.
Sources
- TechCrunch: ChatGPT hallucinated about Soundslice so often the founder made the lie come true
- Adrian Holovaty's blog: the ChatGPT fake feature, firsthand account
- 404 Media: ChatGPT hallucinated a feature, forcing human developers to add it
Related error guides
Slopsquatting: the AI hallucinated an npm package and an attacker registered it
Claude Code Says 'You're Absolutely Right!' and Keeps Applying the Same Broken Fix
The Vibe Oops briefing
One email when something ships to production that should not have. New incidents, new error guides, no filler.