In the world there are different projects making software, some off these software is free to use.This site will only link to sites which provide free software.
From the EfficienSea Project:
- DaMSA AisLib - Java library for handling AIS messages: https://github.com/dma-ais/AisLib
- EfficienSea AIS VHF Datalink Manager: https://github.com/DaMSA/EAVDAM
- Extended INS https://github.com/DaMSA/ee-INS
- A free AIS Decoder and NMEA router: http://web.arundale.co.uk/docs/ais/ais_decoder_v3_downloads.html
- A free multi platform Chartplotter and GPS Navigation software: http://opencpn.org/ocpn/download