Backend Basics

Core: start here

• Background JobWork done outside the request, like sending an email.
• ConfigurationSettings that change between environments, kept out of code.
• Environment VariableA key-value setting passed to processes from their environment.
• Environments (dev, staging, prod)Separate deployments for development, testing and real users.
• Input ValidationChecking every input at the boundary before using it.
• Log LevelsDEBUG, INFO, WARN and ERROR, and when to use each.
• LoggingRecording what the application does so you can debug it later.
• N+1 Query ProblemOne query for a list, then one more query for every item in it.
• ORMMapping database tables to objects in code.
• PaginationReturning large result sets one page at a time.
• RoutingMapping URLs and methods to handler code.
• SessionServer-side memory of a logged-in user, referenced by a random ID the browser sends on each request.
• TimeoutsNever waiting forever on a network call.
• Web FrameworkLibraries like Express, Django, Spring or FastAPI for building web apps.

Core: start here

• Dependency InjectionPassing dependencies in instead of creating them inside.
• Feature FlagsTurning features on and off without deploying.
• Offset vs Cursor PaginationSimple page numbers vs stable, scalable cursors.
• Structured LoggingLogging key-value fields instead of free text.
• The Twelve-Factor AppTwelve practices for building deployable, scalable web services.

• Choosing a Backend LanguageWeighing ecosystem, performance and team skills.
• Context PropagationCarrying request IDs, deadlines and trace context across threads and services.
• Let It CrashRestarting a failed component cleanly instead of handling every error inside it.
• Multi-TenancyServing many customers from one system while keeping their data apart.
• Steady StateDesigning systems to clean up after themselves: purging data, rotating logs.
• Worker and Process ModelsPre-fork workers, threads or an event loop: how a server handles many requests at once.

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• PaginationReturning large result sets one page at a time.

• Feature FlagsTurning features on and off without deploying.

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Nothing here yet.

Core: start here

• Environment VariableA key-value setting passed to processes from their environment.
• LoggingRecording what the application does so you can debug it later.

• Connection PoolingReusing a set of open connections instead of opening new ones.
• Dependency InjectionPassing dependencies in instead of creating them inside.
• Graceful ShutdownFinishing in-flight work before exiting on SIGTERM.
• Offset vs Cursor PaginationSimple page numbers vs stable, scalable cursors.
• Serverless FunctionsRunning code per request without managing servers.
• Structured LoggingLogging key-value fields instead of free text.
• The Twelve-Factor AppTwelve practices for building deployable, scalable web services.
• Third-Party IntegrationsCalling payment, email and other external APIs reliably.

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• BackendThe server side: business logic, data and integrations.
• Business LogicThe rules that make your product what it is.
• ConfigurationSettings that change between environments, kept out of code.
• Environment VariableA key-value setting passed to processes from their environment.
• Environments (dev, staging, prod)Separate deployments for development, testing and real users.
• File UploadsAccepting, validating and storing files from users.
• Filtering and SortingLetting clients narrow down and order results.
• Input ValidationChecking every input at the boundary before using it.
• Log LevelsDEBUG, INFO, WARN and ERROR, and when to use each.
• LoggingRecording what the application does so you can debug it later.
• MVCModel-View-Controller: separating data, presentation and input handling.
• N+1 Query ProblemOne query for a list, then one more query for every item in it.
• PaginationReturning large result sets one page at a time.
• SessionServer-side memory of a logged-in user, referenced by a random ID the browser sends on each request.
• TimeoutsNever waiting forever on a network call.
• Web FrameworkLibraries like Express, Django, Spring or FastAPI for building web apps.
• Web ServerSoftware that accepts HTTP requests and returns responses.
• Web Servers (Nginx, Apache, Caddy)The common servers that sit in front of applications.

Core: start here

• Feature FlagsTurning features on and off without deploying.

• Context PropagationCarrying request IDs, deadlines and trace context across threads and services.

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Nothing here yet.