# Ezequiel Carrizo

> Ezequiel Carrizo is a lead software engineer at The Knot Worldwide who builds and runs three live products: Fabiana, WardenAuth and Interview Sparring.

Ezequiel Carrizo is a lead software engineer at The Knot Worldwide, based in Tenerife, Spain. He has worked in software since 2007 and builds and runs his own products.

## Products

- [Fabiana](https://getfabiana.com): Answers customers on the phone, website chat, email and WhatsApp, in their language, and gets the next step done: a booking, a payment, a lead.
- [WardenAuth](https://wardenauthz.com): Roles, permissions and tenants your app doesn't have to build, and the same rules applied to every tool call your AI agents make.
- [Interview Sparring](https://interviewsparring.com): An AI sparring partner for technical and behavioral interviews. It listens to your answers and coaches you while you speak.

## Career

- 2022–now: Lead Software Engineer, The Knot Worldwide
- 2021–2022: Lead Software Engineer, The Drum
- 2016–2021: Senior Software Engineer, Owl Health
- 2007–2016: QA to Software Engineer, Córdoba, Argentina

## Pages

- [About](https://ezequielcarrizo.com/about/): background, work history and skills
- [Contact](https://ezequielcarrizo.com/contact/): email ezequiel.carrizo.ac@gmail.com
- [Writing](https://ezequielcarrizo.com/blog/): all posts

## Posts

- [I Rebuilt My Site With Zero JavaScript and Got 100 on Mobile Lighthouse](https://ezequielcarrizo.com/blog/engineering/rebuilding-my-site-zero-javascript/): How I rebuilt ezequielcarrizo.com as a static Next.js 16 site with no client JavaScript, no backend and no analytics, and what it took to reach 100 on every Lighthouse category on mobile.
- [How Fabiana Answers a Customer: One LLM Call per Message](https://ezequielcarrizo.com/blog/engineering/how-fabiana-answers-customers/): The architecture behind Fabiana, my AI assistant that answers customers on WhatsApp, email, chat and the phone: an SQS pipeline on Lambda, one structured LLM call per message, and no fixed costs.
- [Deny Wins: How WardenAuth Authorizes Users and AI Agents](https://ezequielcarrizo.com/blog/engineering/how-wardenauth-decides/): How WardenAuth, my authorization API, decides every access check: scopes that inherit, deny-wins policies, an answer that explains itself, and AI agents capped by the user they act for.
- [The Monorepo Playbook: SST v3, AWS, and TypeScript](https://ezequielcarrizo.com/blog/engineering/monorepo-sst-aws-typescript/): How I structured a production monorepo with SST v3: infrastructure-as-code, PR previews, multi-environment deployment, and cost optimization.
- [From Zero to 101 Guides: Scaling Content for SEO](https://ezequielcarrizo.com/blog/engineering/scaling-content-seo-101-guides/): How I wrote and structured 101 interview tip guides for SEO: keyword research, content hierarchy, internationalization, and reaching page one.
- [Building an AI Mock Interview Platform: Architecture Deep Dive](https://ezequielcarrizo.com/blog/engineering/ai-mock-interview-platform-architecture/): The architecture behind Interview Sparring: how AI-powered mock interviews work, from real-time speech analysis to adaptive scoring and feedback.
- [DDD in Serverless: Breaking the Monolith Mindset](https://ezequielcarrizo.com/blog/engineering/ddd-serverless-lambdas/): Applying Domain-Driven Design principles to serverless Lambda functions: bounded contexts, repository pattern, and dependency injection with tsyringe.
- [AWS SES + Serverless: Email Delivery at Scale](https://ezequielcarrizo.com/blog/engineering/aws-ses-serverless-email/): How I set up transactional email with Amazon SES from Lambda functions: domain verification, bounce handling, and staying out of the spam folder.
- [Building a Reusable UI Component Library](https://ezequielcarrizo.com/blog/engineering/building-reusable-ui-library/): The design decisions behind a production-ready React component library: composability, accessibility, and why I built it from scratch.
- [Lessons from Leading Cross-Functional Teams at TKWW](https://ezequielcarrizo.com/blog/engineering/leading-cross-functional-teams/): Real lessons from two years as Technical Software Lead: stakeholder management, risk mitigation, and building high-trust engineering cultures.
- [From IC to Tech Lead: What Nobody Tells You](https://ezequielcarrizo.com/blog/engineering/ic-to-tech-lead/): The transition from individual contributor to tech lead is harder than it looks. Here is what I learned making that shift at The Knot Worldwide.
- [2024 in Review: What I Built and Learned](https://ezequielcarrizo.com/blog/engineering/2024-year-in-review/): Reflecting on a year of growth: from earning my AWS certification to completing a car restoration and rebuilding this very blog.
- [The Hidden Cost of Third-Party Dependencies](https://ezequielcarrizo.com/blog/engineering/hidden-cost-dependencies/): A critical look at dependency bloat in modern JavaScript projects and strategies to keep your bundle lean without sacrificing productivity.
- [TypeScript Patterns I Wish I Knew 5 Years Ago](https://ezequielcarrizo.com/blog/engineering/typescript-patterns-5-years-later/): Practical TypeScript patterns that changed how I write code: template literal types, type guards, satisfies, and const assertions.
- [How I Built a SEO-Optimized Blog with Next.js Static Export](https://ezequielcarrizo.com/blog/engineering/how-i-built-seo-blog-nextjs-static/): A deep dive into the architecture of my personal site: static export, sitemaps, metadata, and why I chose serverless over a CMS.
- [JavaScript if Conditions: AND (&&), OR (||), NOT (!) and Comparison Operators](https://ezequielcarrizo.com/blog/programming/javascript-conditionals-comparison-and-logical-operators/): How to write AND, OR and NOT conditions in a JavaScript if statement, plus equals and not equals (=== and !==), with short examples for beginners.
- [Jumpstart Your Coding Journey with JavaScript](https://ezequielcarrizo.com/blog/programming/jumpstart-your-coding-journey-with-javascript/): Get started with JavaScript programming with this beginner-friendly guide. Learn the basics and kickstart your coding journey.
- [How I Achieved a Perfect 100 Lighthouse Score on My Static Blog](https://ezequielcarrizo.com/blog/engineering/perfect-lighthouse-score/): The concrete steps I took to hit 100 on all four Lighthouse categories: Performance, Accessibility, Best Practices, and SEO on a Next.js static site.
- [Dodge Coronado 1968](https://ezequielcarrizo.com/blog/cars/dodge-coronado-1968/): The Dodge Coronado 1968 is a car that I restored in 2021. It was a great project that I enjoyed a lot.