You asked about Reinforcement Learning
149 people built something like it. 9 are gone.
That is 7% of the ones whose fate we could settle, against 23% across the whole register. 13 were acquired.
| Launched | What it was | Today |
|---|---|---|
| 2019-01-01 | YCrct AI build AI NPCs · rct.ai | still up |
| 2024-06-01 | YCSepal AI Data Development for Advanced AI · sepalai.com | acquired |
| 2024-06-01 | Open-Source Reinforcement Learning (RL) & Fine-tuning for LLMs. · unsloth.ai | still up |
| 2025-01-01 | YCOsmosis Reinforcement Learning (RL) for AI Agents · osmosis.ai | still up |
| 2025-09-01 | Large-scale real-world robot & human data for embodied AI · cortexrobot.ai | still up |
| 2026-01-01 | Robot Cowboys that Herd Cattle with AI Drones · brumby | still up |
| 2026-06-01 | YCFabraix The world's frontier hacker of AI agents. · fabraix.com | still up |
| 2026-06-01 | Training the world's best AI model for quantitative finance. · prodigy.markets | still up |
| 2025-09-01 | YCSylvian Specialized AI Agents. · sylvian.ai | gone |
| 2025-01-01 | AI Agents that automate enterprise software processes · agentin.ai | still up |
| 2026-06-01 | Open source AI gateway that turns your traffic into a better model · experientiallabs.ai | still up |
| 2026-06-01 | YCMarkov Expert computer-use data for frontier AI labs · markovstudios.com | still up |
| 2015-01-01 | Rebuilding healthcare with AI at the core · akidolabs.com | still up |
| 2016-06-01 | YCScale AI Data-centric infrastructure to accelerate the development of AI · scale.com | still up |
| 2021-01-01 | YCEncord The data layer for physical AI · encord.com | still up |
| 2020-06-01 | YCTaktile Transform your decision-making with reliable AI agents in weeks, not… · taktile.com | still up |
| 2022-01-01 | YCvoize We build the AI companion for nurses, to create time for care. · voize.de | still up |
| 2016-01-01 | YCDeepgram Building foundational AI for speech transcription and understanding. · deepgram.com | still up |
| 2021-01-01 | YCCodingal Leading online after-school for kids & teens to learn AI & coding · codingal.com | still up |
| 2020-06-01 | YCHENRY We train AI engineers and connect them with companies. · soyhenry.com | still up |
| 2023-06-01 | End-to-end content, learning, & deal intelligence for B2B sales teams · letter.ai | still up |
| 2021-01-01 | YCMindee AI Document Understanding API · mindee.com | still up |
| 2021-01-01 | YCSoraban AI tax workflow platform for accounting firms · soraban.com | still up |
| 2015-01-01 | Paperspace is a cloud platform for building and scaling AI… · paperspace.com | acquired |
| 2022-01-01 | Compliant-Ready AI for the Enterprise · dynamo.ai | still up |
| 2018-01-01 | PROVEN is using AI, data and personalization to disrupt CPG · provenskincare.com | still up |
| 2019-01-01 | YCOverview Reshaping industrial quality with AI, hardware, and software · overview.ai | still up |
| 2024-06-01 | YCFINNY AI The organic growth engine for financial advisors · finny.com | still up |
| 2024-09-01 | AI tutors for students. · generallearning.com | still up |
| 2022-01-01 | YCLanceDB Open-source, serverless vectordb for production-scale generative AI · lancedb.com | still up |
| 2016-06-01 | YCCrowdAI CrowdAI is the world's leading no-code platform for vision AI · crowdai.com | acquired |
| 2025-01-01 | YCMundo AI High Quality Multilingual Training Data for AI Models · mundoai.world | still up |
| 2022-01-01 | YCSpade Spade is the data and AI platform for modern finance. · spade.com | still up |
| 2018-01-01 | YCAcely Every student's AI coach for college readiness · acely.com | still up |
| 2020-06-01 | Financial data layer for AI-powered finance and accounting · blueonion.ai | still up |
| 2021-06-01 | The most magical personal Voice-Led AI English Learning Buddy for Kids · sparkstudio.co | still up |
| 2017-06-01 | YCD-ID Enable creators and developers to generate realistic AI personas · d-id.com | still up |
| 2021-06-01 | YCMach9 AI CAD Software for Civil Engineering · mach9.ai | still up |
| 2021-06-01 | The fastest way to ship airtight AI · openlayer.com | still up |
| 2023-01-01 | YC222 the AI social facilitator for offline human to human interactions · 222.place | still up |
| 2016-01-01 | YCRevl AI edited video souvenirs as a service · revl.com | still up |
| 2021-01-01 | YCSpokn AI-powered video platform for Internal Comms and HR teams · getspokn.com | still up |
| 2020-01-01 | YCHandoff AI estimator & agent for remodelers. · handoff.ai | still up |
| 2023-01-01 | YCloopfour Workflow automation, without AI hallucinations. · loopfour.com | still up |
| 2020-01-01 | YCPowerX AI powered sensors that save energy, water and emissions · powerx.co | acquired |
| 2020-06-01 | AI-native Robotics · nexterarobotics.com | still up |
| 2019-01-01 | Talent AI improving quality of hire · searchlight.ai | acquired |
| 2023-01-01 | AI-Powered Super Mentor for Test Prep · superkalam.com | still up |
| 2022-01-01 | LLM for Legal in Brazil · lexter.ai | still up |
| 2022-06-01 | YCCerrion Video AI to automatically detect and respond to production line… · cerrion.com | still up |
| 2020-06-01 | AI-native Operating System for Enterprise Ecommerce Companies · hypotenuse.ai | still up |
| 2023-01-01 | Automating Healthcare Revenue Cycle Management with AI Workforce · combinehealth.ai | still up |
| 2018-06-01 | Database for AI · activeloop.ai | still up |
| 2018-01-01 | YCEdwin Edwin is virtual English tutor - an AI-powered service for learning… · edwin.ai | acquired |
| 2020-06-01 | Humanloop is the LLM evals platform for enterprises. · humanloop.com | acquired |
| 2022-06-01 | YCFini Fini | Automate 80% of enterprise support with AI agents · usefini.com | still up |
| 2022-01-01 | Rapid medical data annotation · redbrickai.com | still up |
| 2021-01-01 | Dramatically better search and ads for marketplaces · promoted.ai | acquired |
| 2019-06-01 | YCEARTH AI Predictive Explorer and Driller for Critical Metal Deposits · earth-ai.com | still up |
| 2018-06-01 | YCPhiar We are developing a revolutionary AI-powered augmented reality… · phiar.net | 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.