Guides de décision

HTTP

Which HTTP Error Code Should I Return?

Use this decision tree to select the correct HTTP error status code for your API or web application. Answer a series of yes/no questions about the nature of the request and what went wrong. Covers all common client errors (4xx) and server errors (5xx).

HTTP

Which HTTP Redirect Should I Use?

Choosing the wrong redirect code can break bookmarks, harm SEO, or silently change POST requests to GETs. This decision tree walks you through permanence, method preservation, and client behavior to select the correct 3xx code for your use case.

HTTP

Which HTTP Success Code Should I Return?

Not all successful responses should return 200 OK. This tree guides you to the most precise 2xx code based on what action was taken: creating a resource, accepting work asynchronously, returning no body, or sending partial content.

HTTP

Should I Cache This HTTP Response?

Misconfigured caching is one of the most common sources of security bugs and stale data in web applications. This tree walks through the key questions about personalization, freshness, and revalidation to recommend the right Cache-Control directive for your response.

HTTP

401 vs 403: Which One Should I Return?

The difference between 401 Unauthorized and 403 Forbidden confuses many developers. This short decision tree clarifies the distinction: 401 means 'tell me who you are', while 403 means 'I know who you are and the answer is no'.

SMTP

Why Is My Email Bouncing?

Email bounce codes follow a structured pattern: 4xx for temporary failures (soft bounces) and 5xx for permanent failures (hard bounces). This decision tree helps you diagnose the root cause of delivery failures and decide whether to retry or give up.

SMTP

Which Email Authentication Should I Set Up?

SPF, DKIM, and DMARC are three complementary email authentication standards that together protect your domain from spoofing and improve deliverability. This tree guides you through which records to publish and in what order, based on your DNS access and sending setup.

gRPC

Which gRPC Status Code Should I Return?

gRPC defines 17 canonical status codes that map to common error conditions in distributed systems. Unlike HTTP, gRPC always returns HTTP 200 at the transport layer and encodes the status in trailers. This tree guides you to the right gRPC status code based on what went wrong.

DNS

Why Is DNS Resolution Failing?

DNS resolution failures return specific RCODE values that indicate different categories of problems. This decision tree helps you diagnose whether the issue is connectivity, domain registration, nameserver configuration, or a server-side processing error.

WebSocket

Which WebSocket Close Code Should I Use?

WebSocket connections are closed with a Close frame containing a numeric code and optional reason string. Choosing the right close code helps clients understand whether to reconnect, report an error, or simply move on. This tree covers normal closure, protocol violations, policy enforcement, and server-side errors.

Inter-protocoles

How to Map Errors Across Protocols

Different protocols use different error codes for the same logical conditions. This decision tree helps you find the equivalent error code when integrating HTTP APIs with gRPC backends, WebSocket connections, DNS lookups, or SMTP delivery — keeping your error semantics consistent across layers.

Inter-protocoles

Which Protocol Should I Use?

HTTP, gRPC, WebSocket, SMTP, DNS — each protocol is optimized for a different communication pattern. This decision tree walks you through the key requirements of your use case to recommend the most appropriate protocol for your application.