HTTP 200 OK is the standard success response indicating that the request has been fulfilled. The meaning varies by HTTP method: for GET, the resource is returned in the body; for POST, the result of the action is described; for HEAD, only headers are sent without a body. While seemingly simple, proper use of 200 OK — versus more specific success codes like 201 Created or 204 No Content — significantly impacts API design quality, caching behavior, and client-side logic.
Response includes the status code, standard headers (including Content-Type), and a small diagnostic JSON body describing the request and returned status.
Simulator URL (copy in the app after load — not a normal link):
https://httpstatus.com/api/status/200
Example request:
curl -i "https://httpstatus.com/api/status/200"The request has succeeded.
On this code, Inspector focuses on semantics, headers, and correctness warnings that commonly affect clients and caches.
200 OK is defined in RFC 7231 Section 6.3.1 as the most general successful response. The response payload depends on the method: GET returns the target resource representation, HEAD returns the same headers without a body, POST returns the processing result, and TRACE returns the received request message. Caching: 200 responses to GET are cacheable by default (RFC 7234). The response may include Cache-Control, ETag, Last-Modified, and Vary headers to control caching granularity. A critical design consideration: returning 200 for error conditions (e.g., { "success": false, "error": "not found" }) is an anti-pattern that breaks HTTP semantics, caching, and monitoring tools. CDNs cache 200 responses aggressively — returning errors as 200 means your error pages get cached.
const express = require('express');
const app = express();
// GET - 200 with caching headers
app.get('/api/users/:id', async (req, res) => {
const user = await db.findUser(req.params.id);
if (!user) return res.status(404).json({ error: 'User not found' });
res.set('Cache-Control', 'private, max-age=60');
res.set('ETag', `"${user.version}"`);
res.json(user); // 200 is implicit
});
// Search - 200 even with empty results
app.get('/api/search', async (req, res) => {
const results = await db.search(req.query.q);
res.json({ results, total: results.length }); // 200 OK
});from fastapi import FastAPI, HTTPException
from fastapi.responses import JSONResponse
app = FastAPI()
@app.get('/api/users/{user_id}')
async def get_user(user_id: int):
user = await db.find_user(user_id)
if not user:
raise HTTPException(status_code=404, detail='User not found')
# 200 is the default status code
return {
'id': user.id,
'name': user.name,
'email': user.email
}
@app.get('/api/search')
async def search(q: str = ''):
results = await db.search(q)
return {'results': results, 'total': len(results)} # 200 OK@RestController
@RequestMapping("/api/users")
public class UserController {
@GetMapping("/{id}")
public ResponseEntity<User> getUser(@PathVariable Long id) {
return userRepo.findById(id)
.map(user -> ResponseEntity.ok() // 200
.cacheControl(CacheControl.maxAge(60, TimeUnit.SECONDS))
.eTag(String.valueOf(user.getVersion()))
.body(user))
.orElseThrow(() -> new ResponseStatusException(
HttpStatus.NOT_FOUND, "User not found"));
}
}func getUserHandler(w http.ResponseWriter, r *http.Request) {
id := chi.URLParam(r, "id")
user, err := db.FindUser(id)
if err != nil {
http.Error(w, `{"error":"User not found"}`,
http.StatusNotFound)
return
}
w.Header().Set("Content-Type", "application/json")
w.Header().Set("Cache-Control", "private, max-age=60")
w.Header().Set("ETag", fmt.Sprintf(`"%d"`, user.Version))
// 200 is the default WriteHeader
json.NewEncoder(w).Encode(user)
}