You asked about Developer Tools
29 people built something like it. 1 is gone.
That is 3% of the ones whose fate we could settle, against 23% across the whole register.
| Launched | What it was | Today |
|---|---|---|
| 2025-01-01 | YCMastra The Javascript framework for building AI agents, from the Gatsby devs · mastra.ai | still up |
| 2025-06-01 | YCKERNEL Crazy fast, open source infra for AI agents to use the Internet · kernel.sh | still up |
| 2025-06-01 | Compute substrate for AI agents · dedaluslabs.ai | still up |
| 2025-06-01 | Email Inboxes for AI Agents · agentmail.to | still up |
| 2025-06-01 | Tiny Edge AI For Tiny Devices · cactuscompute.com | still up |
| 2025-01-01 | The LLM Eval and Observability Platform for AI Quality · confident-ai.com | still up |
| 2025-06-01 | YCLuminal Making AI run fast on any hardware. · luminal.com | still up |
| 2025-06-01 | YCEmbedder Hardware-Aware AI for Embedded Software Development · embedder.com | still up |
| 2025-09-01 | YCMoss Real-time semantic search for Conversational AI · moss.dev | still up |
| 2025-06-01 | YCAutosana AI agents for E2E testing across mobile & web · autosana.ai | still up |
| 2025-06-01 | YCLark The E2E testing layer for AI-driven development · getlark.ai | still up |
| 2025-01-01 | An AI teammate that automatically updates your customer-facing docs · promptless.ai | still up |
| 2025-06-01 | Build production-ready apps with AI · modelence.com | still up |
| 2025-06-01 | Open source self-improving layer for AI agents · traceroot.ai | still up |
| 2025-01-01 | Open Source React.js Library for AI Chat · assistant-ui.com | still up |
| 2025-09-01 | YCRovr AI FDE Engine that runs your engineering workflows · withrovr.com | gone |
| 2025-01-01 | YCa0.dev We make mobile apps using AI. · a0.dev | still up |
| 2025-09-01 | Helping humans and AI agents understand massive codebases · sourcebot.dev | still up |
| 2025-06-01 | YCVibeFlow AI content manager that grows your company's online presence · vibeflow.ai | still up |
| 2025-06-01 | YCNozomio product lab. focused on personal ai and context. · nozomio.com | still up |
| 2025-01-01 | AWS for AI Agents · trytruffle.ai | still up |
| 2025-06-01 | YCLotas AI for quantitative trading · lotas.ai | still up |
| 2025-09-01 | AI Agents for Platform Engineering · usekestrel.ai | still up |
| 2025-09-01 | YCLemma Production Monitoring for AI agents · uselemma.ai | still up |
| 2025-09-01 | Find what's losing you customers and money in your AI agent and fix it · thecontextcompany.com | still up |
| 2025-09-01 | YCdari.dev The Routing Layer for AI Agents · dari.dev | still up |
| 2025-01-01 | AI documentation engineer – test & autoimprove stale product docs · quantstruct.com | still up |
| 2025-01-01 | YCAstro The world’s first AI energy developer · astroenergy.ai | still up |
| 2025-01-01 | Reimagining how Machines Learn · lucidic.ai | still up |
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.