diff --git a/Libraries/aprs/ax25.h b/Libraries/aprs/ax25.h
new file mode 100644
--- /dev/null
+++ b/Libraries/aprs/ax25.h
@@ -0,0 +1,23 @@
+#ifndef AX25_H_
+#define AX25_H_
+
+#include <inttypes.h>
+
+struct s_address {
+	char callsign[7];
+	uint8_t ssid;
+};
+
+// Private
+void update_crc(uint8_t a_bit);
+void send_byte(uint8_t a_byte);
+
+// Public
+void ax25_send_byte(uint8_t a_byte);
+void ax25_send_flag(void);
+void ax25_send_string(const char *string);
+void ax25_send_header(const struct s_address *addresses, uint16_t num_addresses);
+void ax25_send_footer(void);
+void ax25_flush_frame(void);
+
+#endif /* AX25_H_ */