Building & Product
How founders use AI for AI in Your Product
The resources behind 15 questions founders actually ask, then the questions themselves, each with a straight answer.
On the AI map, 29 October 2026 Frontier models Open-weight models Decision models
What founders use for ai in your product, ranked by how many answers lean on it.
- YC partners on how model progress should shape what founders build now versus wait on. creators.spotify.com Podcast The 10 Trillion Parameter AI Model With 300 IQ (Lightcone) Y Combinator (Lightcone Podcast)
- The essay that made evals a founder-level topic; failed LLM products almost always skipped this. hamel.dev Article Your AI Product Needs Evals Hamel Husain
- A free written masterclass version if you want the method without the course fee. aakashg.com Guide How to Master AI Evals: Step-by-Step with Hamel and Shreya Aakash Gupta (Product Growth)
- Open-source, config-file evals that run in CI; used by OpenAI and Anthropic themselves. github.com Tool Promptfoo Promptfoo
- Gets your first automated eval running in under an hour. datacamp.com Guide Promptfoo Tutorial: A Hands-On Guide to LLM Evaluation DataCamp
- A current map of the eval tooling landscape so you pick once, correctly. braintrust.dev Article Best Prompt Evaluation Tools (Tested and Compared) Braintrust
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Video
AI Engineer World's Fair 2025: Evals track
AI Engineer conference
- A conversational companion to Hamel's essay with concrete team workflows. humanloop.com Article Why Your AI Product Needs Evals, with Hamel Husain Humanloop
- A live-demo episode: watch error analysis actually being done on screen. podcasts.apple.com Podcast Evals, error analysis, and better prompts | Hamel Husain How I AI (Claire Vo)
- Distils the conference's eval takeaways, including hunting implicit user feedback signals. vellum.ai Article Big Ideas from the AI Engineer World's Fair Vellum
- How to make your AI coding tools carry the eval workload for you. hamelhusain.substack.com Article Evals Skills for Coding Agents Hamel Husain
- Turning evals into a deploy gate so a bad prompt change never reaches users. braintrust.dev Article Best AI Eval Tools for CI/CD Pipelines Braintrust
- A vendor-neutral ranking to cross-check the tool vendors' own comparisons. techsy.io Article 8 LLM Eval Tools Ranked: No Product to Sell TECHSY
- A trusted independent voice explaining why iteration speed is the whole game. simonwillison.net Article Simon Willison on "Your AI Product Needs Evals" Simon Willison
- How to use one model to grade another without inheriting its biases. deepeval.com Article LLM-as-a-Judge: Top evaluation techniques and best practices Confident AI (DeepEval)
- A practical setup guide for automated judging, the technique that makes evals scale. agenta.ai Guide LLM as a Judge: Guide to LLM Evaluation Best Practices Agenta
- The clearest end-to-end explainer of why hallucinations happen and the layered defences that work. lakera.ai Guide LLM Hallucinations: Understand and Tackle AI's Most Persistent Quirk Lakera
- Separates factuality from faithfulness errors and matches each to its fix. getzep.com Article How to Reduce LLM Hallucinations Zep
- A prioritized playbook: grounding and abstention first, verification where errors are expensive. futureagi.com Article How to Reduce LLM Hallucinations: 7 Proven Strategies Future AGI
- Production-focused checklist including the stat that layered guardrails cut hallucination rates 71-89%. airbyte.com Article 8 Ways to Prevent LLM Hallucinations in Production Airbyte
- Validate and auto-retry model outputs against a schema; 6M downloads a month for a reason. github.com Tool Instructor: structured outputs for LLMs Jason Liu (567 Labs)
- The Instructor creator on why validation beats vibes for reliability. latent.space Podcast High Agency Pydantic > VC Backed Frameworks, with Jason Liu Latent Space
- Schema-guaranteed responses kill an entire category of made-up fields and invalid values. developers.openai.com Guide Structured model outputs (OpenAI docs) OpenAI
- Connects structured output techniques across providers in one practical reference. agenta.ai Article The guide to structured outputs and function calling with LLMs Agenta
The questions
Should my startup add AI features, and which ones actually matter to users?
Users do not care that a feature uses AI; they care whether it removes a slow, painful, judgment-heavy step from their day. Start from a specific friction po...
How do founders ship their first AI feature (APIs, wrappers, RAG in plain terms)?
Your first AI feature is usually one API call: send the model your instructions plus the user's input, get text or structured JSON back, and wrap it in your ...
How much does it cost to run AI features, and how do I keep costs sane?
You pay per token (roughly per word) in and out, so cost scales with usage; a small feature can run on tens of dollars a month while a chat-heavy product can...
Which AI model should I build on (GPT, Claude, Gemini, open-source), and how do I avoid locking myself in?
There is no best model, only the best one for your task at your price: test the top two or three on your own examples, not benchmark headlines. Today's short...
How do I test whether my AI feature actually works before launch (evals, in plain terms)?
An eval is just a repeatable test suite for your AI feature: 30-100 real example inputs, the output you expect, and a way to score each run. Start by reading...
How do I stop my AI feature from making things up in front of customers?
Models hallucinate because they are trained to always answer; your job is to constrain them, not to hope. The biggest wins in order: ground answers in your o...
Prompt engineering, RAG, or fine-tuning: which one does my product actually need?
Work up the ladder: better prompts cost hours, RAG costs days and adds your own live data, fine-tuning costs weeks and only changes behaviour and style, not ...
How do I design AI features people trust (chat vs buttons, streaming, showing the work)?
A chat box is rarely the right interface: embedded AI (suggestions inside the existing workflow, one click to accept or reject) builds trust faster because u...
What is my moat if I'm building on someone else's model?
The model is not your moat and never will be; the moat is everything you wrap around it: proprietary data and feedback loops, deep vertical workflow ownershi...
Should I put an AI agent in my product, or is a simple workflow enough?
A workflow follows steps you defined, with the model filling in the reasoning slots; an agent decides its own path with tools in a loop. Workflows are cheape...
Is it safe to send customer data to AI APIs, and what about privacy laws like India's DPDP Act?
The major API providers (OpenAI, Anthropic) do not train on your API data by default, and Anthropic no longer keeps API prompts at all by default, except on ...
How should I price AI features: per seat, per use, or per outcome?
AI broke flat per-seat pricing because every request has a real compute cost; most AI-native companies now run hybrid pricing: a base subscription plus usage...
My AI feature is live. How do I monitor it and make it better with real usage?
Log every AI call with its prompt, response, cost, latency, and user feedback; observability tools like Langfuse or LangSmith give you this in an afternoon a...
What is RAG in AI?
RAG (retrieval-augmented generation) means the AI first looks up passages from a set of documents you choose and then answers from them, instead of relying o...
How do I get an API key for OpenAI or Gemini?
Both take a few minutes and only need a sign-in. For Gemini, open the API keys page in Google AI Studio (aistudio.google.com/apikey): new users get a default...
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