Application programming interface (API)

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Definition

A set of rules that lets one program request services or data from another, often over HTTP using JSON. A safe API validates input, authenticates callers, limits data returned and uses HTTPS.

Example: Return only the fields the client needs.

Found in: syllabus, school notes.

Short version to memorise (key terms bank)

Rules letting software components request data or services from each other.

Where you'll use it in the test

Syllabus area: Y12 Secure Software Architecture.

Question types it can appear in

Multiple choice: Pick the option that matches the definition or example.
Short answer: Define, outline or explain it and tie it to the scenario.
Extended response: Use it as a supporting point linked to the stimulus.

Where it has appeared in the paper

Secure Software Architecture (Part A). Part letters follow each paper’s own layout.

How to use it

A model sentence

General advice, built from the definition and example above

“A set of rules that lets one program request services or data from another, often over HTTP using JSON.” Then apply it: Return only the fields the client needs.

In a short answer, give the definition in your own words first, then tie it to the situation in the question. Do not copy the example above unless it fits the scenario.

Command words used with it

From the linked past questions

Identify: Recognise and name. (2025 HSC Q5 (1 mark): API vulnerabilities)

Go deeper

Flashcard: Application programming interface (API) in Secure Software Architecture (Year 12) · study that set
Memorise: Defensive data input handling: validation, sanitisation, error handling
Key terms bank entry: API
Notes: Safe APIs to minimise vulnerabilities (Secure Software Architecture (Year 12))
Notes: Design, develop and implement a safe application programming interface (API) to minimise… (Secure Software Architecture (Year 12))
Notes: Describe how collaborative work practices between front-end and back-end developers… (Programming for the Web (Year 12))
Full term page: every question, note and marking comment for Application programming interface (API)

Check yourself

Explain “Application programming interface (API)” in one sentence, give an example, and name a question type that could test it.

Reveal the answer

A set of rules that lets one program request services or data from another, often over HTTP using JSON. A safe API validates input, authenticates callers, limits data returned and uses HTTPS.

Example: Return only the fields the client needs.

Could be tested as: Multiple choice, Short answer, Extended response.

Quick multiple choice

Which is the BEST way to reduce the risk of an API exposing more data than intended?

Return only the fields the client needs and require authentication and authorisation on each endpoint
Return the entire database record for every request
Disable error logging
Allow unlimited anonymous requests

Show the answer

Excessive data exposure and weak access control are common API vulnerabilities (cf. 2025 HSC Q5). Also use rate limiting and validate input.

Source: original (written for this study pack; not a NESA question). Open it in the multiple-choice bank.