Y Combinator Application Playbook
Learning
Open playbookDraft and compress answers into plain English
Produce an authentic founder video and truthful demo
Review current YC video rules. On the official video page YC asks for approximately one minute consisting only of founders talking, all founders represented, and natural spontaneous speech from bullet points rather than reading a script. The video is not a promo or a product demo.
Suggested content: founder names and roles, what the company does, why they care or are qualified, strongest fact about progress or insight, and a short closing. Prioritize comprehensible audio, natural delivery and clear communication over production value.
If product demo is requested in a separate field, show one complete real user task: starting condition, action inside the product, result and why it matters. Distinguish a live product from mocks or prototypes. Do not imply simulated behavior is production behavior. Check that a viewer who knows nothing about the startup can understand it without external explanation.
Run cold-read, skeptical and factual reviews
Practice interviews and maintain reusable evidence
Prepare crisp answers to: What are you building? Who specifically needs it? How do you know? What did customers do, not just say? What numbers matter? Why this team? What do competitors miss? How will you win your first ten customers? Why can this be big? What is the largest risk? What changed since applying?
Run unscripted mock interviews with randomized questions and follow-up "Why?" and "How do you know?" probes. Answer first, provide a fact next, admit genuine unknowns and explain how to test them. Jessica Livingston advises conversation and specific interesting details rather than buzzwords or a prewritten pitch.
Perform final consistency and integrity checks, verify links and current submission rules, and log genuine new progress that could be shared appropriately. Do not create an application schedule here; this playbook is intentionally batch-agnostic. End with a retrospective: strongest evidence, greatest uncertainty, rejected or misleading claims, high-value future experiments, and what to rewrite next time.