Since the External API is versioned, it supports specification of a version identifier as part of the standard Accept HTTP request header:

Header Type Description
Accept string application/<version>+<format> is used to specify the API version and format



Accept: application/v1.0.0+json

If that header is not specified, or no version information can be extracted from the header, the assumption is that the request should be executed against the most recent version. If the version specified is not available, 406 (NOT ACCEPTABLE) is returned as the HTTP response code.

With every response, the API version is specified as part of the standard HTTP Content-Type header, as in application/v1.0.0+json.

Versions should be specified as obtained from the Base API call to /versions.


The External API is using basic authentication. In order to make calls to the API, the following standard request headers need to be sent with every request:

Header Type Description
Authorization string Sends username and password as defined in Basic Authentication


There are multiple ways to authorize a request - see the authorization section for more details. In short, the External API either supports specifying the execution user, the execution user’s roles or a combination of the two in which case the execution roles will be added to the execution user’s existing roles.

If no user is specified, Opencast’s anonymous user is used to execute the request, potentially enriched by the roles provided using the X-ROLES request.

Header Type Description
X-API-AS-USER string Id of the user in whose name the request should be executed
X-API-WITH-ROLES string Set of roles, separated by whitespace, that the execution user should be assigned in addition to existing roles.

Formats and Encoding

Content Type

The External API currently supports JSON format only.

Header Type Description
Accept string The expected response format is application/json

If that header is not specified, the Content-Type will be application/<version>+json.

Note that the same header should be used to specify the version of the API that is expected to return the response. In this case, the header looks like this: application/v1+json. See the versioning chapter of the general section for more details.

Encoding of single objects

JSON notation

Single objects are enclosed in curly braces "{}" and are not explicitly named.


  "firstname": "John",
  "lastname": "Doe"

Encoding of collections of objects

JSON notation

Collections of objects are enclosed in braces "[ ... ]" and are not explicitly named.


    "firstname": "Jane",
    "lastname": "Doe"
    "firstname": "John",
    "lastname": "Doe"

Encoding of empty fields

Instead of dropping fields that do not contain a value for a specific data object from the JSON response structure, the respective identity element should be used:

Type Encoding Description
Literals "" Strings and numbers
Objects {} Non-existing objects
Arrays [] Non-existing list of literals or objects


Sorting of result sets is supported by a set of well-defined fields per request, one at a time. Each API request explicitly defines the fields that support sorting.

Multiple sort criteria can be specified as a comma-separated list of pairs such as: Sort Name:ASC or Sort Name:DESC. Adding the suffix ASC or DESC sets the order as ascending or descending order and is mandatory.

Parameter Description
sort Comma-separated list of sort critera


Ordering the list of events by title:

GET /api/events?sort=title:ASC,start_date:DESC


Filtering of result sets is supported by a set of well-defined fields per request. Multiple filter criteria can be defined by specifying a comma-separated list of filters. In this case, the criteria are applied using logical and.

A filter is the filter's name followed by a colon ":" and then the value to filter with so it is the form Filter Name:Value to Filter With.

Each API request explicitly defines the fields that support filtering.

Parameter Description
filter A comma seperated list of filters to limit the results with

Note that filter conditions must be URL encoded.


Filter the list of events by status and by series.

GET /api/events?filter=status%3dpublished,series%3dmath


When loading large result sets, being able to address and access the data in well-defined chunks using a limit and offset is essential. Paging is enabled for all requests that return lists of items.

Paramter Description
limit The maximum number of results to return for a single request
offset The index of the first record to return (counting starts on zero)


From the list of events, return items 50-74.

GET /api/events?limit=25&offset=50