Docs / Yamcs HTTP API / General


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:

GET Retrieve a resource
POST Create a new resource
PATCH Update an existing resource
DELETE Delete a resource


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



Mission Database entries like parameters and containers may be available under different namespaces. When an operation documents the use of /:namespace/:name in the URI, the namespace segment can be repeated for every subsystem in case of hierarchical XTCE names. For example, these resources evaluate to the same parameter resource:


Notice as well the use of %3A and + to URL-encode MDB:OPS Name to the ASCII character set. The server supports UTF-8 but your client may not.

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": "<short>",
    "msg": "<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 this is configurable by your site administrator.


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 at GitHub. Using the protoc compiler, client code can be generated for Java, Python, C++ and more.

The applicable top-level Protobuf messages are documented for every operation separately. If the response status is not between 200 and 299, deserialize the response as of type RestExceptionMessage.