Complete List of YC W24 Companies — Winter 2024 Batch

• Batch size: ~235 companies

• Demo day: April 2024

• Defining theme: LLM application layer maturity

• AI proportion: ~65% of batch described AI as central

• International proportion: ~42%

• Top countries: US, UK, India, Canada, France, Nigeria

• Notable first: Multiple companies raised $10M+ seed rounds before demo day ended

LLM APPLICATIONS AND AI PRODUCTS

Notable W24 AI Application companies:

DEVELOPER TOOLS

Notable W24 Developer Tools companies:

B2B SAAS

Notable W24 B2B SaaS companies:

HEALTHCARE

Notable W24 Healthcare companies:

CLIMATE AND ENERGY

Notable W24 Climate companies:

INDIAN-ORIGIN W24 COMPANIES

THE LLM APPLICATION LAYER MATURES

W24 was the batch where YC partners publicly committed to the thesis that the LLM application layer — products built on top of foundation models with deep workflow integration — was the most important startup opportunity of the decade. This was visible in both the batch composition and the post-demo day fundraising outcomes.

Patterns observed in W24 LLM application companies:

• Average time from demo day to seed round close: 6 weeks (down from 12 weeks in W23)

• Median seed round size for AI companies: $4M (up from $2.5M in W23)

• Proportion of W24 AI companies with enterprise customers at demo day: ~40%

• Most common monetization model: per-seat SaaS with usage-based pricing overlay

THE LLM OBSERVABILITY CATEGORY

W24 produced an unusually high concentration of LLM observability and evaluation companies — Braintrust, Baserun, Portkey, Helicone, LangWatch, Orq.ai, and several others. This cluster emerged because W24 was the first batch where YC companies were experiencing production LLM failures at scale and needed tooling to diagnose them. The observability category's emergence in W24 mirrored the emergence of DevOps observability tools a decade earlier.

POST-W24 FUNDING HIGHLIGHTS

W24 INDIAN COMPANY PERFORMANCE

Indian-origin companies in W24 showed strong post-demo day traction. Portkey AI established itself as the leading LLM gateway product, accumulating 10,000+ developers on its platform within 6 months of demo day. Pingsafe was acquired by SentinelOne in 2024 for approximately $100M — one of the fastest YC batch-to-acquisition stories in recent history.

W24 was a pivotal batch because it coincided with the moment the AI ecosystem transitioned from "anything AI is fundable" to "only AI products with real retention and real enterprise contracts get funded."

The hype-to-execution transition in W24:

Several W24 companies entered demo day with strong demo metrics (impressive AI outputs) but weak product metrics (low retention, no enterprise contracts). These companies struggled to raise post-demo day as investors asked harder questions about why users would pay and continue paying beyond the novelty period.

The W24 companies that raised quickly shared a specific profile: they had at least one enterprise customer with a signed contract, they could describe their retention data specifically, and they could explain why their product improved with usage data — creating a moat that a competitor could not easily replicate.

The commoditization concern in W24:

W24 was the first batch where a significant number of founders explicitly addressed the commoditization risk in their pitches: "What happens when GPT-5 can do what you do?" The founders who answered this question well pointed to workflow integration depth, proprietary training data, or distribution advantages. The founders who answered it poorly pointed to temporary capability advantages that foundation model updates would eliminate.