The CTO Podcast with Fexingo: Technical Leadership, Architecture, and Engineering Org

Episode 79 of The CTO Podcast dives into the engineering behind Datadog's core pipeline. Hosts Lucas and Luna unpack how Datadog re-architected its ingestion, processing, and storage layers to handle over 100 trillion events per day by mid-2026. They explore the shift from a monolithic intake to a sharded, stream-oriented architecture, the decision to build custom compression rather than use off-t...

Lucas and Luna dive into the technical architecture behind Figma's real-time collaboration engine. They explore how Figma moved from a standard web app to a custom multi-user sync layer using Operational Transform and CRDT-inspired techniques, handling hundreds of simultaneous designers editing the same vector without conflict. With specific numbers on latency and data structures, they break down...

In this episode, Lucas and Luna dive into how Stripe rebuilt its core payments engine to handle compliance, currency, and latency across over 100 countries. They explore the architectural decisions behind Stripe's global payment infrastructure, including the unified API that abstracts local banking regulations, the edge-caching layer for 4x faster checkout in emerging markets, and the team structu...

In this episode of The CTO Podcast, Lucas and Luna dive into how Loom rebuilt its video recording and streaming engine to handle over 200 million videos per year while keeping latency under one second for uploads and playback. They explore the architectural shift from monolithic encoding to a microservices pipeline using WebAssembly for client-side transcoding, the trade-offs of moving from FFmpeg...

Lucas and Luna explore how Discord moved from a standard WebRTC stack to a custom UDP transport layer, achieving sub-50ms latency and near-zero packet loss during peak gaming events like Call of Duty launches. They break down the engineering decisions behind Discord's transition from a hobbyist chat app to the backbone of 200 million monthly active users, focusing on the trade-offs between reliabi...

Lucas and Luna dive into the technical decisions behind Airbnb's 2024 search architecture overhaul. With 8 million active listings and billions of queries daily, Airbnb moved from a monolithic Elasticsearch cluster to a multi-tiered retrieval pipeline combining inverted indexes, vector embeddings, and real-time ranking. They explore why Airbnb chose to build custom microservices over managed solut...

In this episode, Lucas and Luna dive into the specific technical decisions GitLab made to scale its CI/CD platform from tens of thousands of pipelines to over one million per day. They focus on the choice of a monolithic application architecture, the use of PostgreSQL partitioning and Redis Cluster, and the trade-offs around job scheduling and queue management. The discussion highlights how GitLab...

Slack's search is used over 10 million times a day. But the original Elasticsearch-based index couldn't keep up as the platform grew to billions of messages. In this episode, the CTO Podcast breaks down how Slack's engineering team rebuilt its search infrastructure from the ground up — migrating from a single Elasticsearch cluster to a custom search engine called 'Search It'. We cover why they mov...

Lucas and Luna dive into Notion's technical journey to rebuild its block-based sync engine for offline-first and real-time collaboration. They explore the architectural shift from optimistic local writes to a hybrid local-sync model, the challenges of conflict resolution with operational transforms, and how Notion handled state reconciliation for millions of users. Specific numbers: over 100 milli...

Notion's block-level architecture was designed for single-user documents. But as the product scaled to 100 million users, real-time collaboration exposed deep cracks in its sync model. This episode unpacks how Notion's engineering team rebuilt its block engine from the ground up — migrating from a naive operational transform approach to a custom hybrid model that blends local-first performance wit...

Episode 69 of The CTO Podcast. Lucas and Luna dive into how MongoDB's engineering team redesigned their core storage engine to handle multi-terabyte workloads without sacrificing developer velocity. They break down the specific challenge: a single customer complaint about a 12-terabyte shard that took 47 hours to rebalance. That complaint triggered a two-year effort to rewrite the WiredTiger stora...

This episode of The CTO Podcast dives into how Doordash rebuilt its delivery logistics platform to handle peak demand during the COVID-19 pandemic and beyond. Lucas and Luna explore the specific architecture decisions behind Doordash's real-time dispatching system, which processes millions of orders per day with sub-second latency. They discuss the shift from a monolithic Rails backend to a micros...

In this episode of The CTO Podcast, Lucas and Luna dive into Cloudflare's massive infrastructure migration: moving 30 million requests per second from a legacy edge architecture to a new proxy stack without a single minute of downtime. They break down the technical challenges — from connection draining to canary deployments — and the cultural discipline behind the rollout. A masterclass in high-st...

In this episode, Lucas and Luna dive into the architectural decisions behind Canva's collaborative design platform, which serves over 100 million monthly active users. They explore how the Australian unicorn rebuilt its rendering engine for real-time collaboration, the technical trade-offs involved in supporting a massive template library, and how Canva's engineering team scaled its infrastructure...

In 2024, GitHub faced an impossible problem: its 15-year-old storage backend, built on bare Git repositories, couldn't keep up with 100 million active repos, AI-generated commits, and terabyte-scale monorepos. This episode drills into how GitHub's engineering team designed and rolled out a custom storage engine called 'GitHub Storage Service' (GSS) without a single user-facing outage. We cover the...

In this episode, Lucas and Luna dive into Walmart's massive supply chain overhaul, focusing on how the retail giant moved from batch processing to real-time data pipelines. They discuss the technical challenges of integrating 12,000 suppliers into a unified platform, the role of edge computing in store-level inventory tracking, and what other companies can learn from Walmart's approach to balancin...

In this episode of The CTO Podcast, Lucas and Luna dive into how Pinterest's engineering team rebuilt its core recommendation engine from a batch-processing pipeline to a real-time, graph-based system serving over 500 million monthly active users. They explore the specific architectural decisions Pinterest made: moving from collaborative filtering to a heterogeneous graph neural network called Pin...

In this episode of The CTO Podcast, Lucas and Luna dive into the technical architecture behind Anthropic's Claude 3, focusing on how the team designed for enterprise-grade reliability at scale. They discuss concrete decisions like sharding policy across GPU clusters, the introduction of 'constitutional AI' as a guardrail system, and how Anthropic's engineering org balances fast iteration with rigo...

In this episode of The CTO Podcast, Lucas and Luna dive into how Spotify rebuilt its core recommender engine from a batch-based collaborative filtering system to a real-time graph neural network serving 600 million users. They explore the specific architectural decisions behind Spotify's migration from Apache Spark and nightly model retraining to a streaming pipeline with TensorFlow and graph embe...

Netflix's content delivery network, Open Connect, delivers over half of the world's internet traffic at peak. In this episode, Lucas and Luna dive deep into the specific architectural decisions Netflix made to scale its CDN from 100 million to 300 million subscribers. They explore the shift from commercial CDNs to a peered, ISP-embedded appliance model, the move from spinning disks to NVMe SSDs, a...

Walmart's supply chain is the largest in the world, moving over 5 billion units annually. In this episode, Lucas and Luna explore how Walmart rebuilt its supply chain on real-time data from edge to shelf. They break down the 2019 shift from batch processing to streaming events, the use of Kafka at massive scale, and how a machine learning model called 'Eddie' predicts demand by the hour. Lucas exp...

Episode 58 of The CTO Podcast goes inside Datadog's engineering org to explore how the company monitors its own 100-terabyte infrastructure. Lucas and Luna walk through Datadog's dogfooding culture, the architectural challenges of running a monitoring platform for itself, and how the team handles alert fatigue, distributed tracing, and log ingestion at massive scale. They discuss specific tools li...

Figma's multiplayer engine lets hundreds of designers edit the same file simultaneously. How did they rebuild it from scratch to handle over 500 concurrent users per document without conflicts or lag? Lucas and Luna break down the architecture: the shift from CRDTs to a custom conflict-resolution layer, the 'change tree' data structure that replaced operational transforms, and the decision to move...

Lucas and Luna break down the architectural decisions behind Cloudflare's global edge network, which handles over 30 million HTTP requests per second. They explore how the company moved from a simple reverse proxy to a distributed system spanning 330 cities, the role of custom-built Nginx configurations, and the trade-offs between latency and consistency. Specific topics include the use of Anycast...

Episode 55 of The CTO Podcast dives into how Stripe rebuilt its payment routing engine to achieve 99.999% uptime. Lucas and Luna break down the architectural shift from a monolithic routing layer to a distributed, deterministic system that handles millions of transactions per second. They explore the team's decision to move away from traditional load balancers, the role of formal verification in r...