Cosmo Router
Open-source, Apache 2.0 GraphQL Federation router written in Go, part of the WunderGraph Cosmo platform.
Type: gateway
Website: https://github.com/wundergraph/cosmo
Features
| Feature | Supported Since | Note |
|---|---|---|
| MutationsJul 2015 | ||
| QueriesJul 2015 | ||
| SubscriptionsJun 2018 | Over graphql-ws, SSE, multipart HTTP and legacy protocols (doc) |
|
| Directives on Variable DefinitionsOct 2021 | ||
| Interfaces on InterfacesOct 2021 | ||
| Repeatable DirectivesOct 2021 | ||
| @specifiedByOct 2021 | partial | Subgraphs accept it, but composition strips it, so clients never see it (doc) |
| Deprecated input valuesSep 2025 | 0.232.1 | |
| Executable documents descriptionsSep 2025 | 0.261.0 | |
| @oneOfSep 2025 | 0.259.0 | |
| 'application/graphql-response+json' media typedraft | - | |
| Directives on directivesdraft | - | |
| Empty selection setsdraft | - | The parser rejects |
| GraphQL over HTTPdraft | partial | GET and POST are supported, but responses always use |
| '@defer'ExperimentalRFC2 | 0.353.0 | Off by default; enable with |
| Fragment ArgumentsExperimentalRFC2 | - | |
| '@stream'ExperimentalRFC2 | - | |
| Deprecated objectsExperimentalRFC1 | - | |
| Empty abstract typesExperimentalRFC1 | - | Empty interfaces and unions are rejected |
| Empty objectsExperimentalRFC1 | - | |
| 'onError' request parameterExperimentalRFC1 | - | In progress in the router's engine (branch) |
| Service capabilitiesExperimentalRFC1 | - | In progress in the router's engine (branch) |
| Field extensionsExperimentalGAP | - | |
| @semanticNonNullExperimentalGAP | partial | Kept in the client schema, but the router does nothing with it. Requires composition 0.45.0 and wgc 0.93.1 (doc) |
| Automatic Persisted QueriesExperimental | 0.140.0 | Off by default (doc) |
| HTTP batchingExperimental | 0.198.0 | Off by default; enable with |
| HTTP QUERY methodExperimental | - | |
| Persisted DocumentsExperimental | 0.36.0 | The protocol for persisted documents is still TBD (doc) |
| Semantic IntrospectionExperimental | - |