APIs, HTTP, and debugging
Opening notes
Welcome the viewer. Explain that this is one lesson in the eight-part Job-Ready Software Engineering series. Set up the outcome before beginning.
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APIs, HTTP, and debugging
Debugging starts with a question
Replace guesses with evidence
Speaker notes
Debugging is not proving that your first theory was right. It is reducing uncertainty.
The request/response contract
- Method and URL
- Headers and body
- Server behavior
- Status and response body
Speaker notes
An API is a contract between systems. Ask which part of the contract was violated: route, method, authentication, input, server behavior, or response shape.
Status codes are signals
- 2xx — success
- 3xx — redirect
- 4xx — request or permission problem
- 5xx — server failure
Speaker notes
Status codes narrow the search; they do not tell the whole story.
A reliable debugging loop
- Reproduce
- Record
- Compare
- Narrow
- Form one hypothesis
- Change one thing
- Verify
Speaker notes
The most expensive debugging habit is changing five things at once. Make one hypothesis and one controlled change.
Evidence to collect
- Exact URL and method
- Timestamp and environment
- Safe request details
- Status and response
- Logs
- Reproduction frequency
Speaker notes
Be careful with tokens and personal data. A good bug report is detailed enough for someone else to reproduce without becoming a security incident.
Demo: diagnose a broken endpoint
POST /api/applications — expected 201 — actual 500
Speaker notes
Use an API client. Compare the payload to the contract. Check the application log. Show how a null field or database constraint creates the failure.
Pause: write the bug report
- Title
- Steps to reproduce
- Expected result
- Actual result
- Evidence
- Suspected cause
Speaker notes
Pause the video and write the report as if a teammate will receive it without a meeting.
Your artifact
- Publish a sanitized bug report
- Include an API collection
- Explain the evidence
Speaker notes
This demonstrates a highly employable skill: turning an unclear failure into a useful investigation.
Make the artifact.
Publish your work, then continue to the next lesson.
Closing notes
Repeat the artifact viewers should create. Invite them to subscribe and join the future live cohort waitlist.