REST API Guidelines

REST API Guidelines

The API is like a language, for developers, so it should be easy to understand and should follow the grammar.

Main topics

API Endpoints

The resources should always be plural in the API endpoint. Each instance of the resource should have an unique ID, which can be passed in the URL to get the detail of the specific resource.

HTTP Verbs

  • method GET on path /gardens should get the list of all gardens
  • method POST on path /gardens should create a new garden with given details
  • method GET on path /gardens/5 should get the detail of garden 5
  • method PUT on path /gardens/5 should update the detail of garden 5
  • method DELETE on path /gardens/5 should delete garden 5

likewise nested resources should be handled like

  • method GET on path /gardens/6/plants should get the list of all plants in garden 6
HTTP verb Action Collection Importance
GETFetch resource*/collection* or */collection/:resourceId*STRICT
POSTCreate resource*/collection*STRICT
PUTUpdate resource*/collection/:resourceId*STRICT
DELETERemove resource*/collection/:resourceId*STRICT
PATCHUpdate resource*/collection/:resourceId*OPTIONAL
OPTIONSSupported resource methods*/collection/:resourceId*OPTIONAL
CONNECTConverts to TCP/IP*/collection/:resourceId*OPTIONAL

HTTP Response Status Codes

HTTP response status codes helps the client to understand the status of the request, whether it failed, passed, the request was wrong or even the API is not available. There are number of standardized codes. These can be broadly divided into 5 categories :

1xxInformationalIt means the request has been received and the process is continuing.
2xxSuccessIt means the action was successfully received, understood, and accepted.
3xxRedirectionIt means further action must be taken in order to complete the request.
4xxClient ErrorIt means the request contains incorrect syntax or cannot be fulfilled.
5xxServer ErrorIt means the server failed to fulfill an apparently valid request.

The following are the important categorization of HTTP codes:

200OKEverything is working
201CREATEDNew resource has been created
204NO CONTENTThe resource was successfully deleted, no response body
304NOT MODIFIEDThe date returned is cached data (data has not changed)
400BAD REQUESTThe request was invalid or cannot be served. The exact error should be explained in the error payload. Eg The REQUEST BODY is not valid .
401UNATHORIZEDThe request requires user authentication.
403FORBIDDENThe server understood the request, but is refusing it or the access is not allowed.
404NOT FOUNDThere is no resource behind the URI.
410GONEGone indicates that the requested resource is no longer available which has been intentionally moved.
500INTERNAL SERVER ERRORAPI developers should avoid this error. If an error occurs in the global catch blog, the stack trace should be logged and not returned as response.
503SERVICE UNAVAILABLE Service Unavailable indicates that the server is down or unavailable to receive and process the request. Mostly if the server is undergoing maintenance

Response Data

Any casing convention is fine, but make sure it is consistent across the application. If the request body or response type is JSON then please follow camelCase to maintain the consistency.

Searching, sorting, filtering and pagination

sort*/cats?sort=weight*sort the cats by its weight in ascending order.
search*/cats?search=kitty*returns the cats having name kitty.
limit*/cats?limit=10*returns only first 10 cats
skip*/cats?skip=5*skips first 5 cats
pagination*/cats?limit=10&skip=5*skips first 5 cats and returns next 10


APIs are not intended to be changed often. But critical and feature upgrades are always appreciated. Given the new APIs should not lead to break the existing products or services using your APIs. is a good example, which has the version number of the API in the path. If there is any major breaking update, we can name the new set of APIs as v2 or v1.x.x

API Examples

  • GET /cats

    List cats

    Status Code : 200

        "fullName": "Kitty"
        "fullName": "Blue"
        "fullName": "Little kitty"
  • POST /cats

    Create cat

    Status Code : 201

  • GET /cats/1

    Get cat detail

    Status Code : 200

      "fullName": "Kitty"
  • PUT /cats/1

    Update cat detail

    Status Code : 200

  • DELETE /cats/1

    Remove cat

    Status Code : 200

Tagged in :
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REST API Guidelines
Checklist for building REST APIs