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

Episode 104 of The API Podcast explores a classic API dilemma: how to evolve an API without breaking the clients that depend on it. Lucas and Luna examine the three dominant versioning strategies — URI versioning, header-based versioning, and query-parameter versioning — and walk through real trade-offs using examples from Stripe, GitHub, and Twilio. They discuss why Stripe moved from URI versioni...

Lucas and Luna dive into prefix compression, a technique that reduces payload size and speeds up API responses by trimming redundant leading characters from repeated values. Using real examples from a ride-sharing app's driver-tracking endpoint and a social media feed, they explain how prefix tables work, where they shine (large arrays of common prefixes), and where they fall short (short or chaot...

Lucas and Luna explore the Stale-While-Revalidate caching strategy—a little-known HTTP cache-control directive that lets APIs serve stale data while fetching a fresh version in the background. They walk through the problem: real APIs like a stock-quote service or a news feed can't afford to block users during cache refreshes. Stale-While-Revalidate solves this by allowing a grace window where old...

Lucas and Luna dive into retry strategies for APIs, focusing on exponential backoff and jitter. They use AWS's SDK default retry policy and Google's failure injection testing as concrete examples, explaining how smart retries prevent cascading failures in distributed systems. They also discuss the trade-off between retries and idempotency, and why exponential backoff with jitter is often better th...

In this milestone 100th episode, Lucas and Luna dive into the world of declarative API schemas and how tools like OpenAPI and AsyncAPI can auto-generate interactive documentation, client libraries, and even server stubs. They explore a real-world case: how a fintech startup used an OpenAPI specification to cut their onboarding time for new API consumers from two weeks to two hours. The conversatio...

When a data pipeline can't keep up with incoming requests, the system doesn't just crash — it pushes back. In episode 99 of The API Podcast, Lucas and Luna explore backpressure as a control mechanism for API traffic surges. They break down how Stripe's API uses HTTP 429 with Retry-After headers to signal clients to slow down, and contrast that with internal backpressure patterns like the leaky buc...

Lucas and Luna dive into the bulkhead pattern for API resilience, drawing on a real-world comparison to ship design and a case study from a major streaming service's 2024 outage. They explain how partitioning resources—like connection pools and thread pools—prevents a single failing endpoint from taking down the whole system. Listeners learn the concrete trade-off between isolation and resource wa...

In this episode of The API Podcast, Lucas and Luna dive into webhooks — the unsung backbone of event-driven API design. They unpack how webhooks differ from polling, why companies like Stripe and GitHub rely on them for real-time notifications, and the hidden complexity of delivery guarantees, retries, and security. Along the way, they explore a real-world case study: how a fintech startup replace...

In this episode of The API Podcast with Fexingo, Lucas and Luna dive into conditional HTTP requests and how they reduce bandwidth and latency by letting clients cache intelligently. They use the example of GitHub's API, which handles over a billion requests per day, to explain how the ETag and Last-Modified headers work in practice. The hosts walk through a real scenario: how a CI/CD tool polling...

Episode 95 of The API Podcast dives into one of the most underrated design patterns in modern web APIs: idempotency keys. Lucas and Luna unpack why safely retrying a payment or order submission without double-charging a user is harder than it looks, and how a simple header like Idempotency-Key solves it. They walk through a concrete example from Stripe's API, discuss the difference between idempot...

In this episode of The API Podcast with Fexingo, Lucas and Luna explore how REST APIs communicate rate limits to clients using standard headers like X-RateLimit-Remaining and Retry-After. They break down the difference between rate limiting and throttling, and walk through a real-world example from the GitHub API, where a developer hitting the 60-request-per-hour limit on unauthenticated endpoints...

In this episode, Lucas and Luna dive into offset pagination, the most common but also most misunderstood API pagination strategy. They explain how SQL-based OFFSET and LIMIT work, why large offsets cause performance degradation, and the real-world risk of phantom rows and data inconsistency. Using the example of a hypothetical shopping app, they illustrate when offset pagination is fine and when i...

In this episode of The API Podcast, Lucas and Luna dive into cursor-based pagination versus traditional offset and limit methods for handling large datasets. They use the example of Twitter's timeline API to explain why cursor tokens prevent the 'page drift' problem where new records shift the offset, causing duplicates or missed items. They also touch on how cursor-based pagination improves perfo...

Lucas and Luna explore what happens when API dependencies vanish — using the 2025 PagerDuty incident that took down thousands of integrations. They discuss graceful degradation, fallback APIs, and why every critical endpoint should have a plan B. With concrete examples from Stripe and Twilio, they show how to build APIs that survive upstream failures. #API #APIDesign #GracefulDegradation #Fallback...

Episode 90 explores GraphQL Federation, an architectural pattern that lets multiple domain teams each own their own GraphQL service while a gateway stitches them into a single unified schema. Lucas and Luna walk through a concrete example: a fictional e-commerce company whose product, inventory, and review APIs each run independently but appear to clients as one endpoint. They explain how the fede...

In this episode of The API Podcast, Lucas and Luna dive into the mechanics of rate limiting — a critical defense against API abuse and server overload. They break down the sliding window algorithm, token bucket vs. leaky bucket approaches, and how companies like GitHub and Twitter communicate limits via headers like X-RateLimit-Remaining. The discussion covers why a 429 status code isn't just a 'n...

Episode 88 of The API Podcast explores HATEOAS - Hypermedia as the Engine of Application State. Lucas and Luna break down how this REST constraint enables API clients to discover actions dynamically through hypermedia links, using GitHub's API as a concrete example. They discuss why HATEOAS reduces client-server coupling, how it compares to static documentation or SDKs, and why adoption remains lo...

In this episode, Lucas and Luna explore how WebSockets enable real-time, two-way communication between clients and servers, going beyond the request-response pattern of REST and even GraphQL subscriptions. They walk through the Slack WebSocket proxy that connects millions of concurrent users to channels without polling. They explain the WebSocket handshake, binary vs text frames, and how a single...

Episode 86 of The API Podcast explores the seemingly simple API key — is it a shared secret, an identifier, or both? Lucas and Luna dissect a real-world case from a developer at a weather data provider whose API key leaked in a public GitHub repo within hours of deployment. They walk through what happened, why the team initially treated the key as just a token, and how they retrofitted scoped keys...

APIs that return thousands of records — think search results, transaction logs, social feeds — don't just dump them in one response. They paginate. In this episode, Lucas and Luna dive into the mechanics behind cursor-based and offset-based pagination, using real examples like GitHub's API and Stripe's list endpoints. They explain why cursor-based pagination scales better for high-write systems an...

In this episode, Lucas and Luna dive into how APIs use JSON Schema as a formal contract between client and server. They explore a real-world case: the Stripe API, which validates every request against a JSON Schema before processing payment intents. Lucas explains how this catches malformed payloads early, reducing 400-level errors by an estimated 30 percent. Luna raises the tension between strict...

Episode 83 of The API Podcast explores content negotiation in web APIs — how clients and servers agree on the format and structure of responses. Through the lens of the Accept and Content-Type headers, Lucas and Luna break down how a single endpoint can serve JSON, XML, or even vendor-specific media types without breaking existing clients. They discuss real-world trade-offs, including why some API...

Episode 82 of The API Podcast explores schema evolution — the challenge of changing an API's data model without breaking every client in the field. Lucas and Luna dig into the practical tactics that let platforms like Stripe and GitHub add fields, deprecate old ones, and even rename properties while keeping old integrations running. They cover additive-only changes, the role of field-level depreca...

When a single API call triggers a chain reaction that takes down an entire platform, that's a cascading failure — and it's more common than you'd think. In this episode, Lucas and Luna break down how modern APIs use circuit breaker patterns to stop failures before they spread. They walk through a real example from a major European cloud provider's 2023 outage: how a misconfigured load balancer on...

Episode 80 of the API Podcast dives into streaming responses—how modern APIs use chunked transfer encoding and server-sent events (SSE) to push data in real time. Lucas and Luna explore the protocol mechanics behind streaming, the differences between SSE and WebSockets, and practical use cases like live dashboards and AI model output. They examine how the Twitter API streams tweets and how GitHub...