HTTP status code for update and delete?

For a PUT request: HTTP 200, HTTP 204 should imply "resource updated successfully". HTTP 201 if the PUT request created a new resource.

For a DELETE request: HTTP 200 or HTTP 204 should imply "resource deleted successfully".

HTTP 202 can also be returned by either operation and would imply that the instruction was accepted by the server, but not fully applied yet. It's possible that the operation fails later, so the client shouldn't fully assume that it was success.

A client that receives a status code it doesn't recognize, but it's starting with 2 should treat it as a 200 OK.

PUT

If an existing resource is modified, either the 200 (OK) or 204 (No Content) response codes SHOULD be sent to indicate successful completion of the request.

DELETE

A successful response SHOULD be 200 (OK) if the response includes an entity describing the status, 202 (Accepted) if the action has not yet been enacted, or 204 (No Content) if the action has been enacted but the response does not include an entity.

Source: IETF: RFC-9110 Method Definitions

HTTP 200 OK: Standard response for successful HTTP requests. The actual response will depend on the request method used.

HTTP 204 No Content: The server successfully processed the request, but is not returning any content

Source: List of HTTP status codes: 2xx Success

Short answer: for both PUT and DELETE, you should send either 200 (OK) or 204 (No Content).

Long answer: here's a complete decision diagram (click to magnify).

Source: https://github.com/for-GET/http-decision-diagram

Here are some Tips:

DELETE

• 200 (if you want send some additional data in the Response) or 204 (recommended).

• 202 Operation deleted has not been committed yet.

• If there's nothing to delete, use 204 or 404 (DELETE operation is idempotent, delete an already deleted item is operation successful, so you can return 204, but it's true that idempotent doesn't necessarily imply the same response)

Other errors:

• 400 Bad Request (Malformed syntax or a bad query is strange but possible).
• 401 Unauthorized Authentication failure
• 403 Forbidden: Authorization failure or invalid Application ID.
• 405 Not Allowed. Sure.
• 409 Resource Conflict can be possible in complex systems.
• And 501, 502 in case of errors.

PUT

If you're updating an element of a collection

• 200/204 with the same reasons as DELETE above.
• 202 if the operation has not been commited yet.

The referenced element doesn't exists:

• PUT can be 201 (if you created the element because that is your behaviour)

• 404 If you don't want to create elements via PUT.

• 400 Bad Request (Malformed syntax or a bad query more common than in case of DELETE).

• 401 Unauthorized

• 403 Forbidden: Authentication failure or invalid Application ID.

• 405 Not Allowed. Sure.

• 409 Resource Conflict can be possible in complex systems, as in DELETE.

• 422 Unprocessable entity It helps to distinguish between a "Bad request" (e.g. malformed XML/JSON) and invalid field values

• And 501, 502 in case of errors.

RFC 2616 describes which status codes to use.

And no, it's not always 200.

Here's some status code, which you should know for your kind of knowledge.

1XX Information Responses

• 100 Continue
• 101 Switching Protocols
• 102 Processing
• 103 Early Hints

2XX Success

• 200 OK
• 201 Created
• 202 Accepted
• 203 Non-Authoritative Information
• 204 No Content
• 205 Reset Content
• 206 Partial Content
• 207 Multi-Status
• 208 Already Reported
• 226 IM Used

3XX Redirection

• 300 Multiple Choices
• 301 Moved Permanently
• 302 Found
• 303 See Other
• 304 Not Modified
• 305 Use Proxy
• 306 Switch Proxy
• 307 Temporary Redirect
• 308 Permanent Redirect

4XX Client errors

• 400 Bad Request
• 401 Unauthorized
• 402 Payment Required
• 403 Forbidden
• 404 Not Found
• 405 Method Not Allowed
• 406 Not Acceptable
• 407 Proxy Authentication Required
• 408 Request Timeout
• 409 Conflict
• 410 Gone
• 411 Length Required
• 412 Precondition Failed
• 413 Payload Too Large
• 414 URI Too Long
• 415 Unsupported Media Type
• 416 Range Not Satisfiable
• 417 Expectation Failed
• 418 I'm a teapot
• 420 Method Failure
• 421 Misdirected Request
• 422 Unprocessable Entity
• 423 Locked
• 424 Failed Dependency
• 426 Upgrade Required
• 428 Precondition Required
• 429 Too Many Requests
• 431 Request Header Fields Too Large
• 451 Unavailable For Legal Reasons

5XX Server errors

• 500 Internal Server error
• 501 Not Implemented
• 502 Bad Gateway
• 503 Service Unavailable
• 504 gateway Timeout
• 505 Http version not supported
• 506 Varient Also negotiate
• 507 Insufficient Storage
• 508 Loop Detected
• 510 Not Extended
• 511 Network Authentication Required

In addition to 200 and 204, 205 (Reset Content) could be a valid response.

The server has fulfilled the request and the user agent SHOULD reset the document view which caused the request to be sent ... [e.g.] clearing of the form in which the input is given.

Since the question delves into if DELETE "should" return 200 vs 204 it is worth considering that some people recommend returning an entity with links so the preference is for 200.

"Instead of returning 204 (No Content), the API should be helpful and suggest places to go. In this example I think one obvious link to provide is to" 'somewhere.com/container/' (minus 'resource') "- the container from which the client just deleted a resource. Perhaps the client wishes to delete more resources, so that would be a helpful link."

http://blog.ploeh.dk/2013/04/30/rest-lesson-learned-avoid-204-responses/

If a client encounters a 204 response, it can either give up, go to the entry point of the API, or go back to the previous resource it visited. Neither option is particularly good.

Personally I would not say 204 is wrong (neither does the author; he says "annoying") because good caching at the client side has many benefits. Best is to be consistent either way.

In June 2014 RFC7231 obsoletes RFC2616. If you are doing REST over HTTP then RFC7231 describes exactly what behaviour is expected from GET, PUT, POST and DELETE

{
    "VALIDATON_ERROR": {
        "code": 512,
        "message": "Validation error"
    },
    "CONTINUE": {
        "code": 100,
        "message": "Continue"
    },
    "SWITCHING_PROTOCOLS": {
        "code": 101,
        "message": "Switching Protocols"
    },
    "PROCESSING": {
        "code": 102,
        "message": "Processing"
    },
    "OK": {
        "code": 200,
        "message": "OK"
    },
    "CREATED": {
        "code": 201,
        "message": "Created"
    },
    "ACCEPTED": {
        "code": 202,
        "message": "Accepted"
    },
    "NON_AUTHORITATIVE_INFORMATION": {
        "code": 203,
        "message": "Non Authoritative Information"
    },
    "NO_CONTENT": {
        "code": 204,
        "message": "No Content"
    },
    "RESET_CONTENT": {
        "code": 205,
        "message": "Reset Content"
    },
    "PARTIAL_CONTENT": {
        "code": 206,
        "message": "Partial Content"
    },
    "MULTI_STATUS": {
        "code": 207,
        "message": "Multi-Status"
    },
    "MULTIPLE_CHOICES": {
        "code": 300,
        "message": "Multiple Choices"
    },
    "MOVED_PERMANENTLY": {
        "code": 301,
        "message": "Moved Permanently"
    },
    "MOVED_TEMPORARILY": {
        "code": 302,
        "message": "Moved Temporarily"
    },
    "SEE_OTHER": {
        "code": 303,
        "message": "See Other"
    },
    "NOT_MODIFIED": {
        "code": 304,
        "message": "Not Modified"
    },
    "USE_PROXY": {
        "code": 305,
        "message": "Use Proxy"
    },
    "TEMPORARY_REDIRECT": {
        "code": 307,
        "message": "Temporary Redirect"
    },
    "PERMANENT_REDIRECT": {
        "code": 308,
        "message": "Permanent Redirect"
    },
    "BAD_REQUEST": {
        "code": 400,
        "message": "Bad Request"
    },
    "UNAUTHORIZED": {
        "code": 401,
        "message": "Unauthorized"
    },
    "PAYMENT_REQUIRED": {
        "code": 402,
        "message": "Payment Required"
    },
    "FORBIDDEN": {
        "code": 403,
        "message": "Forbidden"
    },
    "NOT_FOUND": {
        "code": 404,
        "message": "Not Found"
    },
    "METHOD_NOT_ALLOWED": {
        "code": 405,
        "message": "Method Not Allowed"
    },
    "NOT_ACCEPTABLE": {
        "code": 406,
        "message": "Not Acceptable"
    },
    "PROXY_AUTHENTICATION_REQUIRED": {
        "code": 407,
        "message": "Proxy Authentication Required"
    },
    "REQUEST_TIMEOUT": {
        "code": 408,
        "message": "Request Timeout"
    },
    "CONFLICT": {
        "code": 409,
        "message": "Conflict"
    },
    "GONE": {
        "code": 410,
        "message": "Gone"
    },
    "LENGTH_REQUIRED": {
        "code": 411,
        "message": "Length Required"
    },
    "PRECONDITION_FAILED": {
        "code": 412,
        "message": "Precondition Failed"
    },
    "REQUEST_TOO_LONG": {
        "code": 413,
        "message": "Request Entity Too Large"
    },
    "REQUEST_URI_TOO_LONG": {
        "code": 414,
        "message": "Request-URI Too Long"
    },
    "UNSUPPORTED_MEDIA_TYPE": {
        "code": 415,
        "message": "Unsupported Media Type"
    },
    "REQUESTED_RANGE_NOT_SATISFIABLE": {
        "code": 416,
        "message": "Requested Range Not Satisfiable"
    },
    "EXPECTATION_FAILED": {
        "code": 417,
        "message": "Expectation Failed"
    },
    "IM_A_TEAPOT": {
        "code": 418,
        "message": "I'm a teapot"
    },
    "INSUFFICIENT_SPACE_ON_RESOURCE": {
        "code": 419,
        "message": "Insufficient Space on Resource"
    },
    "METHOD_FAILURE": {
        "code": 420,
        "message": "Method Failure"
    },
    "UNPROCESSABLE_ENTITY": {
        "code": 422,
        "message": "Unprocessable Entity"
    },
    "LOCKED": {
        "code": 423,
        "message": "Locked"
    },
    "FAILED_DEPENDENCY": {
        "code": 424,
        "message": "Failed Dependency"
    },
    "PRECONDITION_REQUIRED": {
        "code": 428,
        "message": "Precondition Required"
    },
    "TOO_MANY_REQUESTS": {
        "code": 429,
        "message": "Too Many Requests"
    },
    "REQUEST_HEADER_FIELDS_TOO_LARGE": {
        "code": 431,
        "message": "Request Header Fields Too"
    },
    "UNAVAILABLE_FOR_LEGAL_REASONS": {
        "code": 451,
        "message": "Unavailable For Legal Reasons"
    },
    "INTERNAL_SERVER_ERROR": {
        "code": 500,
        "message": "Internal Server Error"
    },
    "NOT_IMPLEMENTED": {
        "code": 501,
        "message": "Not Implemented"
    },
    "BAD_GATEWAY": {
        "code": 502,
        "message": "Bad Gateway"
    },
    "SERVICE_UNAVAILABLE": {
        "code": 503,
        "message": "Service Unavailable"
    },
    "GATEWAY_TIMEOUT": {
        "code": 504,
        "message": "Gateway Timeout"
    },
    "HTTP_VERSION_NOT_SUPPORTED": {
        "code": 505,
        "message": "HTTP Version Not Supported"
    },
    "INSUFFICIENT_STORAGE": {
        "code": 507,
        "message": "Insufficient Storage"
    },
    "NETWORK_AUTHENTICATION_REQUIRED": {
        "code": 511,
        "message": "Network Authentication Required"
    }
}

Generally, 200 OK and 201 Created are the best suited for a successful PUT request.

For DELETE method, 202 Accepted and 204 No Content would be the best choice.