Learning term
CORS — Backends and web APIs
CORS defines which browser origins may read an API or send credentials. This card shows its role in “Backends and web APIs” and a safe diagnostic path.
Orientation
CORS defines which browser origins may read an API or send credentials. At this level, separate purpose, input, and visible result. Place CORS within Backends and web APIs before changing settings or files.
Practical use
Check origin, preflight, and credential rules when curl works but the browser blocks the request. Start in a sandbox with neutral examples. Record the expected state, make one controlled change, and compare status output, application behavior, and logs.
Technical understanding
CORS defines which browser origins may read an API or send credentials. Technically, CORS connects through interfaces, configuration, state, or dependencies. Trace data from input to output and check versions, permissions, networking, storage, and resources separately.
Operations and debugging
Check origin, preflight, and credential rules when curl works but the browser blocks the request. In production-like operations, use measurable signals, least privilege, reproducible configuration, and a documented rollback. Preserve evidence, isolate the cause, and verify the correction with the same test.
Exercise
Try it safely
Check origin, preflight, and credential rules when curl works but the browser blocks the request. Open an isolated test environment and run “python --version && curl -s http://127.0.0.1:8000/openapi.json”. Write down the expected output first, do not alter production data, and record one safe next diagnostic step.
python --version && curl -s http://127.0.0.1:8000/openapi.jsonQuick check
Can you explain the purpose, observable state, and most common failure source of CORS — Backends and web APIs in one sentence each? Which evidence would you preserve before changing anything, and which repeated test would prove that the correction actually worked?