Mastering HTTP: When to Use GET vs POST and Their Real Differences

Hello, I'm Lang Wang, a programmer who loves sports. In this article we discuss HTTP request methods and their differences, presented as an interview.

Interviewer: Which HTTP request methods do you commonly use?

Answer: HTTP/1.1 defines eight methods, often referred to as actions, to indicate different operations on the requested URL.

HTTP/1.0 defined three methods: GET, POST, and HEAD.

HTTP/1.1 added five more methods: OPTIONS, PUT, DELETE, TRACE, and CONNECT. In practice, GET and POST are used most frequently.

Interviewer: What are the differences between GET and POST?

GET parameters are placed in the URL and have length limits; POST parameters are sent in the request body without such limits.

GET is less secure because parameters appear in the URL; POST hides data in the body.

GET only accepts ASCII characters for parameters, while POST imposes no character restrictions.

GET parameters are stored in browser history; POST parameters are not.

GET uses URL‑encoded form ( application/x-www-form-urlencoded) only; POST supports multiple encoding types.

GET responses can be cached by browsers automatically; POST responses are not cached unless explicitly configured.

GET requests are safe to repeat (e.g., when navigating back); POST requests may cause duplicate submissions.

Both GET and POST operate over TCP/IP, so they are fundamentally TCP connections. Technically, a GET request can include a request body and a POST request can include URL parameters, but browser and server implementations often restrict this.

URL length is typically limited by browsers to about 2 KB and by servers to about 64 KB. Exceeding these limits may result in the request being rejected.

Parameters are usually appended to the URL after a ? and separated by &, for example:

http://example.com/api?username=langwang&age=26&sex=2

Headers such as token can be added to the request to handle authentication or permission checks.

Regarding security, POST is not inherently safer than GET because both are transmitted in clear text over HTTP. To protect data, HTTPS should be used.

In terms of TCP packets, a GET request typically sends a single packet containing both header and data, while a POST request may involve two packets: one for the header and another for the body after a 100‑Continue response.

GET: browser sends header and data together, server responds with 200 OK. POST: browser sends header, server may respond with 100 Continue, then browser sends data, and the server responds with 200 OK.

Both methods have distinct semantics and should not be used interchangeably. Performance differences are minimal in good network conditions, but in poor conditions the two‑step POST can provide better reliability.