Y Combinator

Accel/Inc

Y Combinator, founded in 2005, is the accelerator every other copies, running two three-month batches a year and a standardised US$500,000 deal. Rather than concentrating capital in a handful of frontier labs, it underwrites AI as a volume business, funding hundreds of application-layer teams per year. Since 2023 most of each batch has been AI-native.

Y Combinator logo
Founded
2005
Headquarters
San Francisco
Leadership
Garry Tan
Standard deal
$500K

How Y Combinator Underwrites AI

Volume Over Conviction

YC does not try to pick the one model company that wins. It writes the same cheque into hundreds of teams per year, accepts a high failure rate, and relies on batch scale plus follow-on rights to capture outliers — the opposite of the concentrated frontier bets made by growth funds.

Application Layer, Not the Model Layer

Frontier training runs are far outside a $500K cheque. The portfolio clusters instead around products built on top of someone else's model: voice agents, coding tools, vertical copilots, and enterprise search where a small team can reach revenue inside a batch.

Developer Tooling as a Repeat Pattern

Speech, evaluation, memory and fine-tuning infrastructure recur batch after batch — Deepgram, AssemblyAI, Vellum, OpenPipe and Mem0 all sell picks and shovels to other AI builders, a category YC has funded for a decade.

Standard Terms as the Real Product

The uniform deal and Demo Day remove price negotiation from the earliest stage. For founders the value is access to 1,000+ investors on a fixed date; for YC it is the ability to originate at scale without competing on valuation.

In depth

Y Combinator was founded in 2005 by Paul Graham, Jessica Livingston, Robert Morris and Trevor Blackwell. Since 2023 the large majority of each batch has described itself as AI-native, making YC the single widest funnel into early-stage AI. The standard deal is US$125K for 7% equity plus a US$375K uncapped SAFE.

AI Portfolio

A selection of YC-backed AI companies, from autonomy and data labelling to the voice, memory and evaluation tooling layers.

  • Scale AI logo
    Scale AIData Infrastructure

    Data labelling and evaluation infrastructure for frontier labs and defence programmes; YC S16.

  • Cruise logo
    CruiseAutonomy

    Self-driving vehicle developer acquired by General Motors; the batch's earliest large autonomy outcome. YC W14.

  • Deepgram logo
    DeepgramSpeech AI

    Speech-to-text and voice agent APIs sold to contact centres and voice product teams. YC W16.

  • AssemblyAI logo
    AssemblyAISpeech AI

    Speech recognition and audio intelligence models delivered as a developer API. YC S17.

  • Ironclad logo
    IroncladLegal AI

    Contract lifecycle platform that added model-driven review and redlining to legal workflows. YC W15.

  • Speak logo
    SpeakConsumer AI

    AI language tutor using speech models for open-ended conversation practice. YC S16.

  • Vapi logo
    VapiVoice Agents

    Developer platform for building and deploying real-time voice agents.

  • Retell AI logo
    Retell AIVoice Agents

    Voice agent infrastructure for inbound and outbound phone operations.

  • Vellum logo
    VellumAI Tooling

    Prompt management, evaluation and deployment tooling for LLM applications.

  • OpenPipe logo
    OpenPipeAI Tooling

    Fine-tuning and distillation platform that converts prompt traffic into cheaper task-specific models.

  • Mem0 logo
    Mem0AI Tooling

    Open-source memory layer giving agents persistent, retrievable user context.

  • Onyx logo
    OnyxEnterprise Search

    Open-source enterprise search and chat over internal company knowledge; formerly Danswer.

Selected Non-AI Portfolio

The pre-AI outcomes that made the batch model credible — not exhaustive, but the alumni most often cited by founders applying today.

  • Airbnb logo
    AirbnbMarketplace

    Home-sharing marketplace; YC W09 and the accelerator's defining outcome.

  • Stripe logo
    StripeFintech

    Payments infrastructure for internet businesses. YC S09.

  • Coinbase logo
    CoinbaseCrypto

    Listed cryptocurrency exchange. YC S12.

  • DoorDash logo
    DoorDashLogistics

    Local delivery marketplace. YC S13.

  • Instacart logo
    InstacartE-commerce

    Grocery delivery and retail media platform. YC S12.

  • Dropbox logo
    DropboxSoftware

    File sync and storage. YC S07.

  • Reddit logo
    RedditConsumer Internet

    Social discussion network funded in YC's first batch in 2005.

  • Twitch logo
    TwitchMedia

    Live-streaming platform, launched out of Justin.tv. YC S07.

Related Rounds

No rounds led by Y Combinator are in the tracker yet. Deals will appear here as they are recorded.

Frequently asked questions

How is YC's US$500K standard deal different from a normal seed round?

There is nothing to negotiate: US$125K for 7% equity plus a US$375K uncapped SAFE, identical for every company. Removing pricing from the earliest stage is the product — founders get a fixed-date market of 1,000+ investors at Demo Day, and YC gets to originate at scale without competing on valuation. A normal seed round is a negotiation; this is a listing.

Why is there no foundation-model lab in YC's AI portfolio?

Cheque physics. Frontier training runs cost billions — Moonshot's July 2026 Series F alone was a reported US$3.5B, 7,000x the US$500K deal — so YC underwrites the layer it can move: voice agents, coding tools, vertical copilots and enterprise search, where a small team can reach revenue inside a three-month batch. The model layer is someone else's balance sheet; YC funds what gets built on it.

Why accept hundreds of companies a year instead of picking winners?

Because the model prices selection as impossible at that stage. YC writes the same cheque into hundreds of teams per batch-year, accepts a high failure rate, and relies on batch scale plus follow-on rights to capture the outliers — the opposite of Conviction's concentrated 19 or NFDG's taste-driven book. Since 2023 the large majority of each batch has been AI-native, making YC the sector's widest funnel.

Why do speech and fine-tuning tools keep appearing batch after batch?

Picks-and-shovels is YC's oldest AI pattern, predating the LLM wave: Deepgram (W16) and AssemblyAI (S17) sold speech APIs years before ChatGPT; Vellum, OpenPipe and Mem0 now sell evaluation, fine-tuning and memory to other AI builders. A batch system notices what builders need, because the builders are the batch — the recurrence is demand observed twice a year, not a thesis written once.

Is Y Combinator an investor or a programme?

Both, deliberately — and the programme is the scarce asset. The standardized US$500K cheque is the entry ticket; the three-month batch and Demo Day are what every other accelerator copies. Unlike a fund, YC does not manage to a portfolio thesis; it manages a repeatable selection process whose output — Airbnb, Stripe, Coinbase, DoorDash — became the credibility that attracts the next batch.