NPLN provides modern game services through gRPC. The decompiled protobuf files can be found here.

The NPLN server is at https://<tenant id>.lp1.t.npln.srv.nintendo.net. The tenant id is always t-<server id>-lp1.

• Metadata
• List of services
• List of games
• Useful tools

The following metadata fields may be included in requests:

The npln-tenant-id field is always required. The authorization and uid fields are only required if the request requires authorization.

If the metadata is invalid, the server returns status code 12 (Unimplemented) on production servers, or 14 (Unavailable) on development servers.

The official library sets the user agent to grpc-c++/1.31.1 grpc-c/11.0.0 (nintendo; chttp2).

Services are never modified in a backward incompatible way, but new methods and services may be added in the future.

• nn.npln.auth.v1.Auth
• nn.npln.friends.v1.Friends
• nn.npln.friends.v1.PresenceService
• nn.npln.gamesync.v1.Gamesync
• nn.npln.hydro.v1.Datastore
• nn.npln.leaderboard.v1.LeaderboardService
• nn.npln.maintenance.v1.MaintenanceScheduleService
• nn.npln.matchmaking.v1.GameSessionService
• nn.npln.matchmaking.v1.Matchmaker
• nn.npln.messaging.v1.Messaging
• nn.npln.ugcstore.v1.Screening
• nn.npln.ugcstore.v1.Ugcstore

Splatoon 3 also implements some custom services:

• nn.npln.toyohr.v1.Canola
• nn.npln.toyohr.v1.CloudSave
• nn.npln.toyohr.v1.CoopScenario
• nn.npln.toyohr.v1.FestService
• nn.npln.toyohr.v1.GameRecord
• nn.npln.toyohr.v1.LobbyMessaging
• nn.npln.toyohr.v1.Locker
• nn.npln.toyohr.v1.Replay
• nn.npln.toyohr.v1.Schedule
• nn.npln.toyohr.v1.UserScreening

Pokemon Scarlet and Violet implement custom services as well:

• nn.npln.timber.v1.CompetitionService
• nn.npln.timber.v1.TradeBoxService

• SDK version table

• grpcui - a simple user interface for gRPC
• grpc-dump - a proxy that dumps gRPC messages (for mitm)