diff --git a/lightning/custom_msg_client.go b/lightning/custom_msg_client.go
new file mode 100644
index 00000000..c34ccfa3
--- /dev/null
+++ b/lightning/custom_msg_client.go
@@ -0,0 +1,12 @@
+package lightning
+
+type CustomMessage struct {
+	PeerId string
+	Type   uint32
+	Data   []byte
+}
+
+type CustomMsgClient interface {
+	Recv() (*CustomMessage, error)
+	Send(*CustomMessage) error
+}
diff --git a/lsps0/codes/code.go b/lsps0/codes/code.go
new file mode 100644
index 00000000..46e0797f
--- /dev/null
+++ b/lsps0/codes/code.go
@@ -0,0 +1,14 @@
+package codes
+
+type Code int32
+
+const (
+	OK             Code = 0
+	Canceled       Code = 1
+	Unknown        Code = 2
+	ParseError     Code = -32700
+	InvalidRequest Code = -32600
+	MethodNotFound Code = -32601
+	InvalidParams  Code = -32602
+	InternalError  Code = -32603
+)
diff --git a/lsps0/jsonrpc/jsonrpc.go b/lsps0/jsonrpc/jsonrpc.go
new file mode 100644
index 00000000..0812cb42
--- /dev/null
+++ b/lsps0/jsonrpc/jsonrpc.go
@@ -0,0 +1,30 @@
+package jsonrpc
+
+import "encoding/json"
+
+var Version = "2.0"
+
+type Request struct {
+	JsonRpc string          `json:"jsonrpc"`
+	Method  string          `json:"method"`
+	Id      string          `json:"id"`
+	Params  json.RawMessage `json:"params"`
+}
+
+type Response struct {
+	JsonRpc string          `json:"jsonrpc"`
+	Id      string          `json:"id"`
+	Result  json.RawMessage `json:"result"`
+}
+
+type Error struct {
+	JsonRpc string    `json:"jsonrpc"`
+	Id      *string   `json:"id"`
+	Error   ErrorBody `json:"error"`
+}
+
+type ErrorBody struct {
+	Code    int32           `json:"code"`
+	Message string          `json:"message"`
+	Data    json.RawMessage `json:"data,omitempty"`
+}
diff --git a/lsps0/protocol_server.go b/lsps0/protocol_server.go
new file mode 100644
index 00000000..f44d1b82
--- /dev/null
+++ b/lsps0/protocol_server.go
@@ -0,0 +1,55 @@
+package lsps0
+
+import "context"
+
+type ProtocolServer interface {
+	ListProtocols(
+		ctx context.Context,
+		req *ListProtocolsRequest,
+	) (*ListProtocolsResponse, error)
+}
+type protocolServer struct {
+	protocols []uint32
+}
+
+type ListProtocolsRequest struct{}
+type ListProtocolsResponse struct {
+	Protocols []uint32 `json:"protocols"`
+}
+
+func NewProtocolServer(supportedProtocols []uint32) ProtocolServer {
+	return &protocolServer{
+		protocols: supportedProtocols,
+	}
+}
+
+func (s *protocolServer) ListProtocols(
+	ctx context.Context,
+	req *ListProtocolsRequest,
+) (*ListProtocolsResponse, error) {
+	return &ListProtocolsResponse{
+		Protocols: s.protocols,
+	}, nil
+}
+
+func RegisterProtocolServer(s ServiceRegistrar, p ProtocolServer) {
+	s.RegisterService(
+		&ServiceDesc{
+			ServiceName: "lsps0",
+			HandlerType: (*ProtocolServer)(nil),
+			Methods: []MethodDesc{
+				{
+					MethodName: "lsps0.listprotocols",
+					Handler: func(srv interface{}, ctx context.Context, dec func(interface{}) error) (interface{}, error) {
+						in := new(ListProtocolsRequest)
+						if err := dec(in); err != nil {
+							return nil, err
+						}
+						return srv.(*protocolServer).ListProtocols(ctx, in)
+					},
+				},
+			},
+		},
+		p,
+	)
+}
diff --git a/lsps0/server.go b/lsps0/server.go
new file mode 100644
index 00000000..55a8858a
--- /dev/null
+++ b/lsps0/server.go
@@ -0,0 +1,267 @@
+package lsps0
+
+import (
+	"context"
+	"encoding/json"
+	"errors"
+	"log"
+	"sync"
+
+	"github.com/breez/lspd/lightning"
+	"github.com/breez/lspd/lsps0/codes"
+	"github.com/breez/lspd/lsps0/jsonrpc"
+	"github.com/breez/lspd/lsps0/status"
+	"golang.org/x/exp/slices"
+)
+
+var ErrAlreadyServing = errors.New("lsps0: already serving")
+var ErrServerStopped = errors.New("lsps0: the server has been stopped")
+var Lsps0MessageType uint32 = 37913
+var BadMessageFormatError string = "bad message format"
+var InternalError string = "internal error"
+
+// ServiceDesc and is constructed from it for internal purposes.
+type serviceInfo struct {
+	// Contains the implementation for the methods in this service.
+	serviceImpl interface{}
+	methods     map[string]*MethodDesc
+}
+
+type methodInfo struct {
+	service *serviceInfo
+	method  *MethodDesc
+}
+
+type Server struct {
+	mu       sync.Mutex
+	serve    bool
+	services map[string]*serviceInfo
+	methods  map[string]*methodInfo
+}
+
+func NewServer() *Server {
+	return &Server{
+		services: make(map[string]*serviceInfo),
+		methods:  make(map[string]*methodInfo),
+	}
+}
+
+func (s *Server) Serve(lis lightning.CustomMsgClient) error {
+	s.mu.Lock()
+	if s.serve {
+		return ErrAlreadyServing
+	}
+	s.serve = true
+	s.mu.Unlock()
+
+	defer func() {
+		s.mu.Lock()
+		s.serve = false
+		s.mu.Unlock()
+	}()
+
+	// TODO: Add a possibility to break this loop.
+	for {
+		msg, err := lis.Recv()
+		if err != nil {
+			log.Printf("lsps0 Serve(): Recv() err != nil: %v", err)
+			continue
+			// TODO: check whether this is a fatal error. delay until next recv.
+		}
+
+		// Ignore any message that is not an lsps0 message
+		if msg.Type != Lsps0MessageType {
+			continue
+		}
+
+		// Make sure there are no 0 bytes
+		if slices.Contains(msg.Data, 0x00) {
+			log.Printf("UNUSUAL: Got custom message containing 0 bytes from peer '%s'.", msg.PeerId)
+			go sendError(lis, msg, nil, status.New(codes.ParseError, BadMessageFormatError))
+			continue
+		}
+
+		req := new(jsonrpc.Request)
+		err = json.Unmarshal(msg.Data, req)
+		if err != nil {
+			log.Printf("UNUSUAL: Failed to unmarshal custom message from peer '%s': %v", msg.PeerId, err)
+			go sendError(lis, msg, nil, status.New(codes.ParseError, BadMessageFormatError))
+			continue
+		}
+
+		// TODO: make sure there is no additional data after parsing the object
+
+		if req == nil {
+			log.Printf("UNUSUAL: req == nil after unmarshal custom message from peer '%s': %v", msg.PeerId, err)
+			go sendError(lis, msg, nil, status.New(codes.ParseError, BadMessageFormatError))
+			continue
+		}
+
+		if req.JsonRpc != jsonrpc.Version {
+			log.Printf("UNUSUAL: jsonrpc version is '%s' in custom message from peer '%s': %v", req.JsonRpc, msg.PeerId, err)
+			go sendError(lis, msg, req, status.Newf(codes.InvalidRequest, "Expected jsonrpc %s, found %s", jsonrpc.Version, req.JsonRpc))
+			continue
+		}
+
+		m, ok := s.methods[req.Method]
+		if !ok {
+			log.Printf("UNUSUAL: peer '%s' requested method '%s', but it does not exist.", msg.PeerId, req.Method)
+			go sendError(lis, msg, req, status.New(codes.MethodNotFound, "method not found"))
+			continue
+		}
+
+		df := func(v interface{}) error {
+			if err := json.Unmarshal(req.Params, v); err != nil {
+				return status.Newf(codes.InvalidParams, "invalid params").Err()
+			}
+
+			return nil
+		}
+		r, err := m.method.Handler(m.service.serviceImpl, context.TODO(), df)
+		if err != nil {
+			s, ok := status.FromError(err)
+			if !ok {
+				log.Printf("Internal error when processing custom message '%s' from peer '%s': %v", string(msg.Data), msg.PeerId, err)
+				s = status.New(codes.InternalError, InternalError)
+			}
+
+			go sendError(lis, msg, req, s)
+			continue
+		}
+
+		go sendResponse(lis, msg, req, r)
+	}
+}
+
+func sendResponse(
+	lis lightning.CustomMsgClient,
+	in *lightning.CustomMessage,
+	req *jsonrpc.Request,
+	params interface{},
+) {
+	rd, err := json.Marshal(params)
+	if err != nil {
+		log.Printf("Failed to mashal response params '%+v'", params)
+		sendError(lis, in, req, status.New(codes.InternalError, InternalError))
+		return
+	}
+
+	resp := &jsonrpc.Response{
+		JsonRpc: jsonrpc.Version,
+		Id:      req.Id,
+		Result:  rd,
+	}
+	res, err := json.Marshal(resp)
+	if err != nil {
+		log.Printf("Failed to mashal response '%+v'", resp)
+		sendError(lis, in, req, status.New(codes.InternalError, InternalError))
+		return
+	}
+
+	msg := &lightning.CustomMessage{
+		PeerId: in.PeerId,
+		Type:   Lsps0MessageType,
+		Data:   res,
+	}
+
+	err = lis.Send(msg)
+	if err != nil {
+		log.Printf("Failed to send message '%s' to peer '%s': %v", string(msg.Data), msg.PeerId, err)
+		// TODO: Retry?
+		return
+	}
+}
+
+func sendError(
+	lis lightning.CustomMsgClient,
+	in *lightning.CustomMessage,
+	req *jsonrpc.Request,
+	status *status.Status,
+) {
+	var id *string
+	if req != nil {
+		id = &req.Id
+	}
+	resp := &jsonrpc.Error{
+		JsonRpc: jsonrpc.Version,
+		Id:      id,
+		Error: jsonrpc.ErrorBody{
+			Code:    int32(status.Code),
+			Message: status.Message,
+			Data:    nil,
+		},
+	}
+
+	res, err := json.Marshal(resp)
+	if err != nil {
+		log.Printf("Failed to mashal response '%+v'", resp)
+		return
+	}
+
+	msg := &lightning.CustomMessage{
+		PeerId: in.PeerId,
+		Type:   Lsps0MessageType,
+		Data:   res,
+	}
+
+	err = lis.Send(msg)
+	if err != nil {
+		log.Printf("Failed to send message '%s' to peer '%s': %v", string(msg.Data), msg.PeerId, err)
+		return
+	}
+}
+
+func (s *Server) RegisterService(desc *ServiceDesc, impl interface{}) {
+	s.mu.Lock()
+	defer s.mu.Unlock()
+	log.Printf("RegisterService(%q)", desc.ServiceName)
+	if s.serve {
+		log.Fatalf("lsps0: Server.RegisterService after Server.Serve for %q", desc.ServiceName)
+	}
+	if _, ok := s.services[desc.ServiceName]; ok {
+		log.Fatalf("lsps0: Server.RegisterService found duplicate service registration for %q", desc.ServiceName)
+	}
+	info := &serviceInfo{
+		serviceImpl: impl,
+		methods:     make(map[string]*MethodDesc),
+	}
+	for i := range desc.Methods {
+		d := &desc.Methods[i]
+		if _, ok := s.methods[d.MethodName]; ok {
+			log.Fatalf("lsps0: Server.RegisterService found duplicate method registration for %q", d.MethodName)
+		}
+		info.methods[d.MethodName] = d
+		s.methods[d.MethodName] = &methodInfo{
+			service: info,
+			method:  d,
+		}
+	}
+	s.services[desc.ServiceName] = info
+}
+
+type ServiceDesc struct {
+	ServiceName string
+	// The pointer to the service interface. Used to check whether the user
+	// provided implementation satisfies the interface requirements.
+	HandlerType interface{}
+	Methods     []MethodDesc
+}
+
+type MethodDesc struct {
+	MethodName string
+	Handler    methodHandler
+}
+
+type methodHandler func(srv interface{}, ctx context.Context, dec func(interface{}) error) (interface{}, error)
+
+// ServiceRegistrar wraps a single method that supports service registration. It
+// enables users to pass concrete types other than grpc.Server to the service
+// registration methods exported by the IDL generated code.
+type ServiceRegistrar interface {
+	// RegisterService registers a service and its implementation to the
+	// concrete type implementing this interface.  It may not be called
+	// once the server has started serving.
+	// desc describes the service and its methods and handlers. impl is the
+	// service implementation which is passed to the method handlers.
+	RegisterService(desc *ServiceDesc, impl interface{})
+}
diff --git a/lsps0/setup_test.go b/lsps0/setup_test.go
new file mode 100644
index 00000000..6a6717ba
--- /dev/null
+++ b/lsps0/setup_test.go
@@ -0,0 +1,62 @@
+package lsps0
+
+import (
+	"log"
+	"testing"
+
+	"github.com/breez/lspd/lightning"
+)
+
+type MockLightningImpl struct {
+	lightning.CustomMsgClient
+	msg  *lightning.CustomMessage
+	err  error
+	resp chan *lightning.CustomMessage
+}
+
+func newMock(msg *lightning.CustomMessage, err error) *MockLightningImpl {
+	return &MockLightningImpl{
+		msg:  msg,
+		err:  err,
+		resp: make(chan *lightning.CustomMessage),
+	}
+}
+
+func (m *MockLightningImpl) Recv() (*lightning.CustomMessage, error) {
+	if m.msg != nil {
+		return m.msg, nil
+	}
+
+	return nil, m.err
+}
+
+func (m *MockLightningImpl) Send(c *lightning.CustomMessage) error {
+	m.resp <- c
+	return nil
+}
+
+func TestSetup(t *testing.T) {
+	srv := NewServer()
+	pSrv := &protocolServer{}
+	RegisterProtocolServer(srv, pSrv)
+	rawMsg := `{
+		"method": "lsps0.listprotocols",
+		"jsonrpc": "2.0",
+		"id": "example#3cad6a54d302edba4c9ade2f7ffac098",
+		"params": {}
+	  }`
+	mock := newMock(
+		&lightning.CustomMessage{
+			PeerId: "AAA",
+			Type:   37913,
+			Data:   []byte(rawMsg),
+		},
+		nil,
+	)
+
+	go srv.Serve(mock)
+
+	resp := <-mock.resp
+	log.Printf("%+v", resp)
+	log.Print(string(resp.Data))
+}
diff --git a/lsps0/status/status.go b/lsps0/status/status.go
new file mode 100644
index 00000000..19ac0515
--- /dev/null
+++ b/lsps0/status/status.go
@@ -0,0 +1,62 @@
+package status
+
+import (
+	"fmt"
+
+	"github.com/breez/lspd/lsps0/codes"
+)
+
+type Status struct {
+	Code    codes.Code
+	Message string
+}
+
+func New(c codes.Code, msg string) *Status {
+	return &Status{Code: c, Message: msg}
+}
+
+func Newf(c codes.Code, format string, a ...interface{}) *Status {
+	return New(c, fmt.Sprintf(format, a...))
+}
+
+func FromError(err error) (s *Status, ok bool) {
+	if err == nil {
+		return nil, true
+	}
+	if se, ok := err.(interface {
+		Status() *Status
+	}); ok {
+		return se.Status(), true
+	}
+	return New(codes.Unknown, err.Error()), false
+}
+
+// Convert is a convenience function which removes the need to handle the
+// boolean return value from FromError.
+func Convert(err error) *Status {
+	s, _ := FromError(err)
+	return s
+}
+
+func (s *Status) Err() error {
+	if s.Code == codes.OK {
+		return nil
+	}
+	return &Error{s: s}
+}
+
+func (s *Status) String() string {
+	return fmt.Sprintf("lsps0 error: code = %d desc = %s", int32(s.Code), s.Message)
+}
+
+type Error struct {
+	s *Status
+}
+
+func (e *Error) Error() string {
+	return e.s.String()
+}
+
+func (e *Error) Lsps0Status() *Status {
+	return e.s
+}