diff --git a/types/logger.go b/types/logger.go
new file mode 100644
index 0000000000..f736b01209
--- /dev/null
+++ b/types/logger.go
@@ -0,0 +1,49 @@
+package types
+
+import (
+	"github.com/tendermint/tmlibs/log"
+)
+
+// MemLogger logs to memory
+type MemLogger interface {
+	log.Logger
+	Logs() []LogEntry
+}
+
+// LogEntry is an entry in a log
+type LogEntry struct {
+	Level   string
+	Message string
+	Keyvals []interface{}
+}
+
+type memLogger struct {
+	entries *[]LogEntry
+}
+
+func (l memLogger) Debug(msg string, keyvals ...interface{}) {
+	*l.entries = append(*l.entries, LogEntry{"debug", msg, keyvals})
+}
+
+func (l memLogger) Info(msg string, keyvals ...interface{}) {
+	*l.entries = append(*l.entries, LogEntry{"info", msg, keyvals})
+}
+
+func (l memLogger) Error(msg string, keyvals ...interface{}) {
+	*l.entries = append(*l.entries, LogEntry{"error", msg, keyvals})
+}
+
+func (l memLogger) With(keyvals ...interface{}) log.Logger {
+	panic("not implemented")
+}
+
+func (l memLogger) Logs() []LogEntry {
+	return *l.entries
+}
+
+func NewMemLogger() MemLogger {
+	entries := make([]LogEntry, 0)
+	return &memLogger{
+		entries: &entries,
+	}
+}
diff --git a/types/logger_test.go b/types/logger_test.go
new file mode 100644
index 0000000000..e8cb51e113
--- /dev/null
+++ b/types/logger_test.go
@@ -0,0 +1,17 @@
+package types
+
+import (
+	"testing"
+
+	"github.com/stretchr/testify/require"
+)
+
+func TestMemLogger(t *testing.T) {
+	logger := NewMemLogger()
+	logger.Info("msg")
+	require.Equal(t, logger.Logs(), []LogEntry{LogEntry{"info", "msg", nil}})
+	logger.Debug("msg2")
+	require.Equal(t, logger.Logs(), []LogEntry{LogEntry{"info", "msg", nil}, LogEntry{"debug", "msg2", nil}})
+	logger.Error("msg3", 2)
+	require.Equal(t, logger.Logs(), []LogEntry{LogEntry{"info", "msg", nil}, LogEntry{"debug", "msg2", nil}, LogEntry{"error", "msg3", []interface{}{2}}})
+}