@aldas please take a look when you get a chance.

Hi, this is a "feature" that Echo uses. c.response.Status = code sets the code for status, which will be used with next responseWriter.Write call and until there have not been "Write" calls the echo.JSONSerializer.Serialize implementation can decide to use different status code.

I really do not want to touch this part as it could introduce subtle bugs for people that rely on this "feature".

Hi @aldas,

Thank you very much for taking the time to review and for the clear explanation — I really appreciate your insight!

I proposed this change because c.JSON() currently allows multiple calls in the same handler without any warning, unlike most other response methods (XML(), Blob(), etc.) that use WriteHeader() and correctly log "response already committed".

Minimal example showing the difference:

// /multiple-json → no warnings
	e.GET("/multiple", func(c echo.Context) error {
		responses := []Response{
			{ID: 1, Name: "first"},
			{ID: 2, Name: "second"},
			{ID: 3, Name: "third"},
		}
		c.JSON(200, responses[0])
		c.JSON(200, responses[1])
		c.JSON(200, responses[2])
		return nil
	})

// /multiple-xml → warns twice
	e.GET("/multiple_xml", func(c echo.Context) error {
		responses := []Response{
			{ID: 1, Name: "first"},
			{ID: 2, Name: "second"},
			{ID: 3, Name: "third"},
		}

		c.XML(200, responses[0])
		c.XML(200, responses[1])
		c.XML(200, responses[2])

		return nil
	})

the logs:

⇨ http server started on [::]:8080
method=GET, uri=/multiple, status=200
{"time":"2026-01-21T18:05:17.741384+06:00","level":"WARN","prefix":"echo","file":"response.go","line":"59","message":"response already committed"}
{"time":"2026-01-21T18:05:17.741707+06:00","level":"WARN","prefix":"echo","file":"response.go","line":"59","message":"response already committed"}
method=GET, uri=/multiple_xml, status=200

I thought aligning JSON() with the other methods would help catch accidental multiple-response mistakes more consistently.

Seems that in v5 this part has been changed. It is currently as

For history sake: c.response.Status = code was added in #1880 (v4.4.0)

I am not going to touch this part in v4 anymore - it works as it is and we are only doing security and bugfixes in v4. But I will check if v5 needs tinkering in that part.

okay. Thanks for the clarification.
I'll be in touch if I run into other issues or have another PR to contribute.

Hey @raju-mechatronics, thanks for taking the initiative here. Even though this PR didn’t get merged, it’s great to have people digging into the library’s internals and reviewing how things work. Thanks!