Kounta by Lightspeed uses an OAuth 2.0 compliant RESTful API for easy integration with third-party applications.
Kounta by Lightspeed’s REST API is based at https://api.kounta.com/v1/. There is no unencrypted (non-SSL) version available.
Add-ons are created and managed from within Kounta by Lightspeed. There you will find your Client ID and Client Secret for authenticating with the API.
To find out more information about creating your Kounta by Lightspeed add-on, see this knowledge base article.
Two types of authentication are available:
For more details, see the section on Authentication.
Requests and responses will use JSON.
When sending data via POST or PUT, specify application/json
            as the format of the data you’re sending in the Content-Type header of your request.
            Any other value will result in a 400 Bad Request response status.
The format of the response body is determined by the file extension of the requested
            endpoint, which is .json. Alternatively,
            you can omit the file extension if you include the aforementioned format in your
                Accept header. If you omit the Accept header and the file
            extension, you’ll get a 406 Not Acceptable response status.
Data in Kounta by Lightspeed is represented in these formats:
true or false.Understanding data types isn’t critical, but it can help you avoid problems like
            inadvertently trimming leading zeroes off phone numbers and rendering null
            as a string.
In some cases an id field with a number type may represent a 64-bit integer, in which case we will also provide an id_str string representation
            of that number, as some programming languages may have difficulty interpreting 64-bit integers.
CRUD operations follow a few standard patterns. Deviations from these patterns are noted in the documents for individual actions.
GET requests result in 200 OK response
                statuses.POST requests result in 201 Created response
                statuses, and Location headers containing the GET URIs of
                the newly created resources.PUT requests result in 200 OK response
                statuses, and include the updated record in the form of the corresponding
                    GET action.DELETE requests result in 204 No Content
                response statuses.Additionally:
GET
                    /v1/customers ) often include abridged versions of
                records, containing only descriptive information (e.g. name,
                    email) and an id. In these cases, you can
                    GET the individual records by id for more detailed
                records.When you request a
            list
            of records (e.g.
            GET
                /v1/companies/5678/customers 
            
            to list all customers),
            you’ll receive a maximum of
            25
            results. To retrieve the entire result
            set, you’ll need to request additional pages.
        
Each page will include the
            X-Next-Page
            header that will contain the full URL to request the next set of 25
            results. This process can be repeated until all the records have
            been returned.
        
Regarding the cursor provided by X-Next-Page:
X-Next-Page header is not present to retrieve all
                resources from a paginated API.Responses to GET requests will include Etag headers. Subsequent
            requests to the same endpoints should include this header’s value in an
                If-None-Match header. If we send you a 304 Not Modified
            response, you can save bandwidth and lighten our server load by using your cached
            copy.
Read more about Etag headers and HTTP caching here.
Kounta by Lightspeed will use standard HTTP status codes when your requests cannot be satisfied.
Additional error information will be sent in the response body as key-value pairs,
            including an error code error, an error description
                error_description, and other diagnostically useful information.
Error responses are OAuth 2.0 compliant.
For simplicity, PATCH and PUT requests are identically treated
            as partial updates, i.e. only fields included in the request are altered. This
            documentation will always specify PUT, but you can use PATCH
            and PUT interchangeably if you like.
There are plenty of good plugins for both Firefox and Chrome for testing REST APIs.
If you prefer to use cURL or something a little less
            sophisticated, try sending an X-Pretty-Print: 1 header with your requests.
            We'll format the output with nice indentation to make it easier to read.