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API OverviewΒΆ

Yamcs provides an HTTP API allowing external tools to integrate with Yamcs resources. Most HTTP endpoints send and expect JSON messages.


If you develop in Python consider using the Python Client which provides an idiomatic mapping for most of the operations documented here.

HTTP Verbs

The supported HTTP verbs are:


Retrieve a resource


Create a new resource


Update an existing resource


Delete a resource


All timestamps are returned as UTC and formatted according to ISO 8601. For example:

2015-08-26T08:08:40.724Z 2015-08-26

Error Handling

When an exception is caught while handling an HTTP request, the server will try to give some feedback to the client by wrapping it in a generic exception message like so:

  "exception" : {
    "type": string, // Short
    "msg": string // Long

Clients should check on whether the status code is between 200 and 299, and if not, interpret the response with the above structure.


Cross-origin Resource Sharing (CORS) allows access to the Yamcs HTTP API from a remotely hosted web page. This is the HTML5 way of bypassing the self-origin policy typically enforced by browsers. With CORS, the browser will issue a preflight request to Yamcs to verify that it allows browser requests from the originating web page.

CORS is off by default on Yamcs Server, but available through configuration.


All API methods are designed for JSON-over-HTTP. Matching type definitions in this documentation are written in TypeScript syntax because of its high readability. Note however that we do not currently mark parameters as optional (?).


As an alternative to JSON, most endpoints also support Google Protocol Buffers for a lighter footprint. To mark a request as Protobuf, set this HTTP header:

Content-Type: application/protobuf

If you also want to server to respond with Protobuf messages, add the Accept header:

Accept: application/protobuf

The proto files are available on GitHub. Using the protoc compiler, client code can be generated for Java, Python, C++ and more.

If the response status is not between 200 and 299, deserialize the response as of type yamcs.api.ExceptionMessage.