Difference Between GET and POST
GET vs POST compared — URL params vs request body, idempotency, caching and when to use each — with examples and web development interview questions.
Expected Interview Answer
GET retrieves data and puts its parameters in the URL query string, making it idempotent, cacheable, and safe (no side effects), while POST submits data in the request body to create or change server state, making it non-idempotent and not cacheable by default.
GET is meant for reading: because parameters ride in the URL, requests can be bookmarked, cached, and logged, but that also caps how much data you can send and exposes it in the address bar. POST carries data in the body, so it handles large or sensitive payloads and is used to create resources or trigger changes. Repeating a GET yields the same result and no side effect, whereas repeating a POST may create duplicate resources — which is why forms warn about resubmission.
- GET: cacheable, bookmarkable, and safe for reads
- GET: idempotent — repeating it changes nothing
- POST: sends large or sensitive data in the body
- POST: creates resources and triggers state changes
AI Mentor Explanation
GET is like asking the scoreboard operator to read out the current score — you can ask again and again and nothing changes, and anyone nearby hears the same public answer. POST is like handing in a new team-sheet that alters the line-up — do it twice and you risk two conflicting sheets. Reading the score is safe and repeatable; submitting a sheet changes state and should not be blindly repeated. That is exactly the GET-versus-POST distinction.
Step-by-Step Explanation
Step 1
Purpose
GET reads data; POST creates or changes server state.
Step 2
Where data goes
GET puts params in the URL query string; POST puts them in the request body.
Step 3
Idempotency & caching
GET is idempotent and cacheable; POST is neither by default.
Step 4
Size & visibility
GET is length-limited and visible in the URL; POST handles large or sensitive payloads.
What Interviewer Expects
- GET for reads, POST for state changes
- Parameters in the URL vs the request body
- GET idempotent and cacheable; POST not
- Awareness of size limits and URL visibility for GET
Common Mistakes
- Using GET for actions that change data
- Believing POST is inherently secure (it still needs HTTPS)
- Putting sensitive data in a GET query string
- Thinking POST is always slower or heavier than GET
Best Answer (HR Friendly)
“GET is for reading data — it puts its info in the web address and can be repeated safely, like refreshing a page. POST is for sending data that changes something, like submitting a form, and its data goes in the request body. You use GET to look things up and POST to create or change them.”
Code Example
GET /search?q=laptop&page=2 HTTP/1.1 (params in the URL, cacheable)
Host: shop.example.com
POST /orders HTTP/1.1 (data in the body, changes state)
Host: shop.example.com
Content-Type: application/json
{ "item": "laptop", "qty": 1 }Follow-up Questions
- What does it mean for an HTTP method to be idempotent?
- When would you use PUT or PATCH instead of POST?
- Why should you not send sensitive data in a GET request?
- Is a GET request response always cacheable?
MCQ Practice
1. Where does a GET request put its parameters?
GET appends parameters to the URL as a query string, which is why they are visible.
2. Which statement is true?
Repeating a GET has no side effect; repeating a POST may create duplicates.
3. Which method should you use to submit a form that creates a record?
POST sends data in the body to create or change server-side state.
Flash Cards
GET vs POST — purpose? — GET reads data; POST creates or changes server state.
Where do parameters go? — GET: URL query string. POST: request body.
Is GET idempotent? — Yes — repeating it has no side effect and it is cacheable.
Why not put secrets in GET? — Query strings appear in URLs, browser history, and server logs.