The API Podcast with Fexingo: REST, GraphQL, and Modern Web APIs

When an API is overwhelmed, how should it behave? In this episode, Lucas and Luna explore the concept of graceful degradation — designing APIs that remain partially functional under extreme load instead of returning 503 errors for every endpoint. Lucas explains how Stripe's API prioritises critical endpoints like payment processing over less essential ones like invoice PDF generation during traffi...

Episode 78 dives into a practical API pattern that backend teams at Uber and GitHub use to cut round trips by up to 90 percent: bulk endpoints. Lucas and Luna walk through the difference between repeated single calls and a single batch request, using concrete examples like Uber's batch ride-status check and GitHub's GraphQL bulk mutations. They discuss trade-offs like error handling, payload size...

Episode 77 of The API Podcast with Fexingo dives into semantic versioning for web APIs—how version numbers like 2.1.3 communicate breaking changes, new features, and patches. Lucas and Luna explore real-world cases from Stripe, GitHub, and the Node.js ecosystem, and unpack why 'semver' became the de facto standard for API contracts. They discuss the tension between strict semver and pragmatic pre-...

Lucas and Luna dive into the API gateway pattern—a reverse proxy that sits in front of microservices to handle authentication, rate limiting, request routing, and analytics. They discuss how companies like Netflix and Shopify use gateways to offload cross-cutting concerns, enforce policies without touching individual services, and simplify client-side code. Lucas explains the difference between a...

In this episode of The API Podcast, Lucas and Luna dive into the often overlooked but critical practice of backward compatibility testing for APIs. Using a concrete example from a major social media platform's API v3 release that broke thousands of integrations in 2025, they explain how automated contract testing with tools like OpenAPI and JSON Schema can catch breaking changes before they hit pr...

Episode 74 of The API Podcast dives into the mechanics of webhooks — the unsung backbone of real-time event-driven APIs. Lucas and Luna break down how platforms like Stripe and GitHub use webhooks to push data the moment something happens, saving developers from constant polling. They explore the delivery contract between senders and receivers: retry logic, signature verification, and idempotency....

In this episode of The API Podcast, Lucas and Luna dive into idempotency keys — the backend pattern that powers safe retries in payment APIs, order systems, and anywhere duplicate requests would be catastrophic. They walk through how Stripe popularized the `Idempotency-Key` header, what happens when a client sends the same key twice, and why naive retry logic without idempotency can bill a custome...

Lucas and Luna dig into the art and science of API error messages. They explore how well-crafted error responses — with specific codes, actionable descriptions, and standard formats like RFC 7807 — turn debugging from guesswork into a guided process. The episode contrasts vague 500 Internal Server errors with detailed responses that include error IDs, validation hints, and retry policies. They exa...

In this episode of The API Podcast, Lucas and Luna dive into the messy reality of API versioning. Most developers dread the day they need to change an endpoint without breaking every client. Lucas walks through the main strategies — URI versioning, header-based negotiation, and query parameter versioning — using real-world examples like Stripe and Twilio. He explains why Stripe's approach of embed...

In episode 70 of The API Podcast, Lucas and Luna dive deep into HTTP conditional requests — the unsung mechanism that lets APIs skip sending unchanged data, saving bandwidth and speeding up responses. They break down the ETag and Last-Modified headers, the difference between strong and weak validators, and how conditional GETs and PUTs prevent conflicts in distributed systems. Using concrete examp...

When an API is overwhelmed, sending back a 429 status code is only half the story. The real art is telling the client exactly when to try again using the Retry-After header. In this episode, Lucas and Luna dig into how Stripe, GitHub, and Twitter handle rate-limit backoff, why naive retry logic can make an outage worse, and how delta-seconds vs. HTTP-date formats create subtle bugs. They walk thro...

In this episode of The API Podcast, Lucas and Luna explore the hidden business logic behind API rate limiting. Why do companies like GitHub, Stripe, and Twitter impose limits on how many requests you can make per minute? Lucas breaks down the three main strategies — token bucket, leaky bucket, and sliding window — and explains how rate limiting is not just a technical safeguard but a pricing lever...

Episode 67 of The API Podcast breaks down the HATEOAS constraint of REST — an often-overlooked principle that turns APIs into self-documenting, navigable systems. Lucas and Luna explore how HATEOAS enables client-side discovery via hypermedia links, using GitHub's API and the Stripe API as concrete examples. They discuss when HATEOAS adds real value versus when it's overkill, the implementation ch...

Episode 66 of The API Podcast dives into canonical resource names — the unsung architectural pattern that keeps large-scale APIs from descending into chaos. Lucas and Luna unpack how naming conventions like 'crn://cloud.example.com/project/abc123/table/xyz' reduce ambiguity across environments, enable idempotent retries, and make multi-region replication possible. They walk through a concrete exam...

In this episode, Lucas and Luna dive into one of the trickiest problems in API design: ensuring that a request is processed exactly once, even when networks drop, retry, or duplicate messages. They explore the technical pattern behind idempotency keys — a mechanism used by Stripe, PayPal, and modern payment APIs to prevent double charges without sacrificing reliability. Lucas explains how the conc...

Episode 64 of The API Podcast digs into query cost analysis — a technique APIs use to measure and cap the computational weight of each request before it hits the database. Lucas and Luna explore how GitHub's GraphQL API assigns point costs to nested queries, how Shopify's REST API charges for field depth, and why platforms like Contentful, Stripe, and Netflix adopt this model. They discuss the dif...

Episode 63 of The API Podcast dives into cursor-based keyset pagination: why offset-limit breaks under scale, how Twitter and Stripe switched to opaque cursors, and what PostgreSQL `WHERE id > $cursor` means for your backend. Lucas explains the mechanics — including performance cliffs at high offsets, tiebreaker columns for stable ordering, and why GraphQL Relay's connection spec predates the curr...

In this episode, Lucas and Luna dive into how JSON Schema is reshaping API contract validation beyond simple type checking. They explore real-world examples like how Stripe's API uses JSON Schema to enforce complex payment request structures, catching invalid payloads before they hit the backend. The hosts break down the difference between JSON Schema and OpenAPI, discuss how schema validation red...

Lucas and Luna dive into the mechanics of CORS (Cross-Origin Resource Sharing) — the browser security protocol that every API developer has to wrestle with. They break down how CORS preflight requests work, why the browser sends an OPTIONS request before the actual API call, and what happens when headers like Access-Control-Allow-Origin are misconfigured. Using a real-world example of a fintech st...

In this episode of The API Podcast with Fexingo, Lucas and Luna explore content negotiation—the HTTP mechanism that lets a single API endpoint return JSON, XML, HTML, or even binary formats based on the client's Accept header. Using a real example from GitHub's API, they trace how the Accept header evolved from a simple content-type switch to a powerful tool for versioning and feature flags. Liste...

In episode 59 of The API Podcast, Lucas and Luna explore how HTTP caching can dramatically reduce API latency and server load. They dive into the mechanics of Cache-Control headers, ETags, and conditional requests, using the real-world example of how GitHub's API cut response times by over 60% by implementing smart caching. The hosts discuss the difference between private and public caches, the ro...

Episode 58 of The API Podcast. Lucas and Luna explore how GraphQL unions and interfaces clean up messy API responses that previously required multiple round trips or awkward nullable fields. Using the example of a social media feed that mixes text posts, images, and polls, they show how unions let clients request heterogeneous data in a single query with type-safe handling. They also discuss perfo...

Episode 57 of The API Podcast dives into prefix compression—a technique that slashes JSON payload size by eliminating repeated keys across arrays. Lucas and Luna break down how it works using a real-world example: a 1,000-order JSON blob that goes from 87 KB to 34 KB with a simple dictionary approach. They explore where prefix compression shines (high-cardinality arrays with repetitive key structu...

In this episode of The API Podcast, Lucas and Luna dive into the world of API mocking — why frontend teams don't have to wait for backend APIs to be ready. They walk through a real case: a fintech startup that cut its feature delivery time by 40% by using mock servers with tools like WireMock and Mock Service Worker. They discuss the difference between static stubs and dynamic mocks, the pitfalls...

Episode 55 of The API Podcast: Lucas and Luna dive into the hidden pitfalls of API pagination — how a simple pattern like cursor-based pagination prevented a major social media platform from going down during a 2025 traffic surge. They walk through the difference between offset and cursor pagination, why the Twitter API's v1 pagination broke under load, and what developers can learn from GitHub's...