You asked about Developer Tools
Nobody in the register described anything this way.
| Launched | What it was | Today |
|---|---|---|
| 2023-01-01 | YCFern Instantly offer SDKs and API Docs · buildwithfern.com | acquired |
| 2023-01-01 | YCLangfuse Open source LLM engineering platform · langfuse.com | acquired |
| 2023-01-01 | Know what your LLM is doing — and why it’s failing · traceloop.com | acquired |
| 2023-01-01 | The open source, fullstack monitoring platform: stop guessing why… · highlight.io | acquired |
| 2023-06-01 | Open source GenAI development platform · flowiseai.com | acquired |
| 2023-01-01 | YCHelicone LLM Observability for Developers · helicone.ai | acquired |
| 2023-06-01 | YCGlide Crypto Deposits, Wallet Funding, and Pay-with-crypto Infra · buildwithglide.com | acquired |
| 2023-01-01 | The interface for your database · outerbase.com | acquired |
| 2023-01-01 | YCOpenInt Open Source Embedded Product Integrations · openint.dev | acquired |
| 2023-01-01 | YCVocode Open source Voice AI · vocode.dev | acquired |
| 2023-01-01 | YCArroyo Cloud-native stream processing · arroyo.dev | acquired |
| 2023-06-01 | YCPeerDB Fast, native ETL for Postgres 🐘 🚀 · peerdb.io | acquired |
| 2023-06-01 | YCChatter Dead simple LLM testing and iteration · chatter.anish.xyz | acquired |
| 2023-01-01 | Open source tools & services for reliable AI Agents & AI Applications · dagworks.io | acquired |
| 2023-06-01 | YCContinue Pioneering open-source coding agent · continue.dev | acquired |
How this compares
The register re-probes every domain it holds. Some that answered last month stop answering. We send that list — what went quiet, and what it was — once a month. Nothing else.
How this was made. Show HN entries are every post from 2021 to 2023 with at least five points that linked to its own domain; code hosts and free hosting are excluded, because a repository outlives the effort behind it. Product Hunt entries needed 100 votes — a far higher bar, so they are the promoted top slice rather than a like-for-like sample. Both are judged by asking the domain whether it still answers: gone means it no longer resolves, refuses the connection, serves a parking page, or says plainly that it shut down. An HTTP error is not counted as gone — a server answering 404 is one somebody still pays for, and an audit of 25 gone-calls found two such sites alive with only a moved homepage. Y Combinator entries use the status YC publishes itself, which is why only those can say acquired. Squatted domains — a lapsed name now serving somebody else's site — are not detected, so these figures run slightly low.