Latest Interviews

How To Use AI In Your Startup

Brad, Pete, Gustav, Nicola

The Y Combinator Spring Batch application deadline of February 11th offers selected startups a $500,000 investment and critical network access, with a strong emphasis on relocating to the San Francisco Bay Area to stay synchronized with rapidly evolving market conditions. Founders are advised to integrate large language models into their core product or operations rather than merely pivoting for trendiness, leveraging their physical proximity to industry leaders to identify automation opportunities in sectors like healthcare and legacy software replacement. Case studies such as WAPI illustrate how embedding within the SF community enabled an early pivot to voice AI, contrasting with remote companies that failed to adapt due to an informational lag in understanding current technological capabilities.

How do OpenAI’s o1 and o3 models perform complex reasoning?

OpenAI's O1 model utilizes a "chain of thought" reasoning mechanism to solve complex problems by decomposing them into sequential steps, a strategy originally formalized by Google Brain researchers in 2022. This approach enables the system to dynamically identify errors and adjust its logic rather than relying on simple next-token prediction, significantly improving accuracy in tasks requiring multi-step calculation. By explicitly walking through intermediate stages, such as determining total slices and calculating consumption before finding the remainder, the model mirrors human problem-solving to ensure precise outcomes.

YC Partner and Algolia co-founder Nicolas Dessaigne’s advice for founders starting out.

Nicolas Dessaigne

Founders are urged to immediately launch imperfect products rather than waiting for a perfect idea, prioritizing rapid iteration and direct user engagement to validate market assumptions. This approach rejects over-engineering in favor of a "crappy, quick, and dirty" methodology that secures essential feedback through high-touch interactions with early adopters. By accepting short-term technical debt and imperfections, entrepreneurs can quickly pivot to build the correct product and capitalize on the market's forgiving memory.

Starting A Company? The Key Terms You Should Know | Startup School

Dalton Caldwell

This session defines critical startup financial mechanics, including burn rate, profitability thresholds, and the structural differences between angel, seed, and Series A funding rounds. It distinguishes between equity instruments like convertible notes and SAFEs while explaining how metrics such as ARR and Total Addressable Market inform valuation and growth strategy. The discussion concludes by outlining the transition from finding product-market fit to scaling operations, ultimately leading toward an IPO or sustained bootstrapping.

The best consumer companies incorporate both virality and network effect to grow organically.

Metcalfe's Law posits that a network's value scales with the square of its user base, transforming a single-user platform like WhatsApp from worthless to globally vital. This dynamic illustrates how the mathematical relationship between nodes and utility drives exponential growth for individual participants. Consequently, consumer companies achieve organic expansion by strategically combining distinct mechanisms of virality and network effects.

How to Use OCaml's Coercion Operator

camels

This session explores standard OCaml's subtyping and coercion mechanisms, emphasizing how the `:>` operator enables compile-time type checks without runtime overhead or data reallocation. The discussion details value inclusion principles for polymorphic variants, recursive subtyping relations, and the specific constraints imposed by private type abbreviations to enforce invariants. While confirming that list coercions remain free at runtime, the presentation notes upcoming analysis of variant annotations and object types in future sessions.

Stripe Head of Design Katie Dill Reviews Startup Websites

Katie Dill, Aaron Epstein

This session establishes core web design principles prioritizing immediate value clarity and mobile responsiveness while critiquing six specific healthcare and B2B technology sites. Reviewers identified critical usability failures across these platforms, including excessive scrolling on Mito Health, visual clutter on Cygnaz, and confusing brand identity on Taiv, which collectively risk user abandonment. The discussion concludes with actionable recommendations to align visual hierarchy, consistent typography, and clear calls-to-action with user scanning behaviors to boost trust and conversion rates.

How To Convert Customers With Cold Emails | Startup School

Aaron Epstein

This event details a data-driven outreach framework where founders must personally execute high-volume email campaigns using warm introductions or targeted cold strategies to secure B2B customers. The speaker outlines a specific funnel architecture that requires sending dozens of daily messages while applying seven principles of effective copy, such as humanized tone, deep personalization, and clear calls to action, to maximize response rates. By analyzing case studies of both failed and successful campaigns, the presentation emphasizes that manual, founder-led execution is essential for building initial traction before any automation is introduced.

How To Keep Your Users | Startup School

David Lieb

YC Group Partner David Leib leverages his experience scaling Bump and Google Photos to argue that high cohort retention is the definitive quantitative signal of product-market fit. He details precise methodologies for defining user actions, selecting appropriate measurement intervals, and interpreting retention curve shapes to distinguish sustainable growth from a churn-heavy treadmill. By avoiding common analytical pitfalls and applying strategies like user acquisition targeting and onboarding optimization, founders can transform cohort data into a actionable roadmap for building scalable, long-term businesses.

OCaml's New Proposed "include functor" Syntax | OCaml Unboxed

Goldfirere

Jane Street is developing an "include functor" feature for the OCaml compiler that allows modules to directly include functor results based on their own preceding definitions. This innovation eliminates the need for cumbersome intermediate wrapper modules and manual reordering, streamlining the implementation of repetitive patterns like reverse array iteration. A working compiler version supporting this syntax is currently available for testing, with plans to upstream the feature to the mainstream OCaml distribution.

Down to the wires: Africa’s digital lag

Rosie Bloor, Jason Palmer, Ore Ogunbiyi, Sophie Pedder, John Bleasdale

The event analyzes Africa's critical digital infrastructure deficit, highlighting how energy shortages and regulatory barriers threaten to exclude the continent from $16 trillion in potential AI-driven economic growth. It further examines the Paris Olympics' environmental contradictions, where a billion-euro cleanup of the Seine failed to prevent bacterial contamination during the triathlon despite the river's vital role in global logistics. Finally, the discussion retrospectively evaluates the enduring success of the *Blair Witch Project*, detailing its record-breaking $250 million return on a $35,000 budget through innovative viral marketing and psychological storytelling techniques.

How To Price For B2B | Startup School

Tom Blomfield

Founders are advised to anchor pricing in a collaborative value equation that quantifies customer ROI, setting rates between 25% and 50% of that value to ensure healthy margins while retaining two-thirds of the benefit for the client. The strategy explicitly discourages cost-plus or predatory price wars, instead urging a shift toward recurring revenue models and short, metric-driven pilots to mitigate revenue volatility. By treating cloud credits as real costs and avoiding public price transparency for enterprise deals, this framework enables startups to secure sustainable growth without triggering a race to the bottom.

When you’re pre-product market fit, sales is a job for the founders.

The event asserts that early-stage B2B founders possess the unique capability to sell their products before achieving product-market fit, rendering external sales hires premature and ineffective. Success in this phase requires founders to leverage their vision for high-volume experimentation and establish tight feedback loops between sales efforts and product development. This distinction highlights pre-PMF sales as an exclusively entrepreneurial role, fundamentally different from the specialized functions assumed after a company validates its market.

Enterprise Sales | Startup School

Pete Koomen, Pete Kuhman

Optimizely co-founder Pete Kuhman outlines a rigorous enterprise sales framework for technical founders, emphasizing that selling before product-market fit requires experimentation with targeted prospecting and personalized outreach. The strategy prioritizes deep discovery during initial calls, uses product-specific narratives to demonstrate value during demos, and treats pricing as a signal of problem severity rather than a fixed metric. By actively managing implementation roadmaps to ensure customer adoption and navigating procurement hurdles with internal champions, founders can transform sales skills into a transferable superpower for fundraising and hiring.

Programming with OCaml's Local Mode | OCaml Unboxed

Jane Street Doe Camel

A Jane Street team member demonstrates practical limitations of the OCaml "Locals" region-based memory management system while optimizing the `best_of_prime_widgets` function to avoid heap allocation. To resolve type mismatches where local lists must escape their regions, the implementation employs a custom zero-overhead `global` wrapper type alongside a recursive map function annotated with `exclave` constraints. Although the solution successfully maintains local allocation for list structures while treating elements as global, the speaker identifies these manual workarounds as sharp corners requiring future improvements through mode polymorphism.