You asked about Reinforcement Learning
157 people built something like it. 9 are gone.
That is 6% 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 |
| 2025-01-01 | YCHUD Platform and marketplace for RL environments and AI data · hud.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 |
| 2026-01-01 | YCBrumby Robot Cowboys that Herd Cattle with AI Drones · brumby | still up |
| 2023-01-01 | YCVelos AI BPO for Specialty Insurance MGAs · tryvelos.com | still up |
| 2025-09-01 | Large-scale real-world robot & human data for embodied AI · cortexrobot.ai | still up |
| 2026-06-01 | Training the world's best AI model for quantitative finance. · prodigy.markets | still up |
| 2026-06-01 | YCMarkov Expert computer-use data for frontier AI labs · markovstudios.com | still up |
| 2026-06-01 | YCFabraix The world's frontier hacker of AI agents. · fabraix.com | still up |
| 2026-06-01 | Open source AI gateway that turns your traffic into better models · experientiallabs.ai | still up |
| 2025-01-01 | Foundational model research · agentin.ai | still up |
| 2025-09-01 | YCSylvian Specialized AI Agents. · sylvian.ai | gone |
| 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 |
| 2020-06-01 | YCTaktile Transform your decision-making with reliable AI agents in weeks, not… · taktile.com | still up |
| 2021-01-01 | YCEncord The data layer for physical AI · encord.com | still up |
| 2022-01-01 | YCvoize We build the AI companion for nurses, to create time for care. · voize.de | still up |
| 2022-07-12 | pixieapp.co | moved |
| 2016-01-01 | YCDeepgram Building foundational AI for speech transcription and understanding. · deepgram.com | still up |
| 2020-06-01 | YCHENRY We train AI engineers and connect them with companies. · soyhenry.com | still up |
| 2021-01-01 | YCCodingal Leading online after-school for kids & teens to learn AI & coding · codingal.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 |
| 2022-03-10 | prepform.com | still up |
| 2015-01-01 | Paperspace is a cloud platform for building and scaling AI… · paperspace.com | acquired |
| 2021-01-01 | YCSoraban AI tax workflow platform for accounting firms · soraban.com | still up |
| 2018-01-01 | PROVEN is using AI, data and personalization to disrupt CPG · provenskincare.com | still up |
| 2022-01-01 | Compliant-Ready AI for the Enterprise · dynamo.ai | still up |
| 2019-01-01 | YCOverview Reshaping industrial quality with AI, hardware, and software · overview.ai | still up |
| 2022-01-01 | YCLanceDB Open-source, serverless vectordb for production-scale generative AI · lancedb.com | 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 |
| 2016-06-01 | YCCrowdAI CrowdAI is the world's leading no-code platform for vision AI · crowdai.com | acquired |
| 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 |
| 2025-01-01 | YCMundo AI The data layer for perceptual intelligence · mundoai.world | 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 |
| 2020-06-01 | Financial data layer for AI-powered finance and accounting · blueonion.ai | 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 |
| 2019-01-01 | Talent AI improving quality of hire · searchlight.ai | acquired |
| 2020-06-01 | AI-native Robotics · nexterarobotics.com | still up |
| 2020-01-01 | YCPowerX AI powered sensors that save energy, water and emissions · powerx.co | acquired |
| 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 |
| 2021-01-01 | YCSpokn AI-powered video platform for Internal Comms and HR teams · getspokn.com | still up |
| 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 |
| 2023-04-06 | koodup.com | 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 |
| 2022-06-01 | YCFini Fini | Automate 80% of enterprise support with AI agents · usefini.com | still up |
| 2020-06-01 | Humanloop is the LLM evals platform for enterprises. · humanloop.com | acquired |
How this compares
Y Combinator reports its own outcomes, including acquisitions. The other two are judged by asking the domain, so they are not measured the same way and are never averaged together.
Older launches have had longer to die, so this slope is expected. A year that broke it would mean something is wrong with the checking.
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.