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 [1]:

• DaMSA AisLib - Java library for handling AIS messages:  https://github.com/dma-ais/AisLib
• EfficienSea AIS VHF Datalink Manager: https://github.com/DaMSA/EAVDAM [2]
• Extended INS https://github.com/DaMSA/ee-INS [3]

From Arundale [4]:

• A free AIS Decoder and NMEA router: https://arundaleais.github.io/docs/ais/ais_decoder_v3_downloads.html [5]
• The mirror website and sourcecode is available on: https://arundaleais.github.io/docs/ais/ais_decoder.html
  and the source: https://github.com/arundaleais

From OpenCPN [6]:

• A free multi platform Chartplotter and GPS Navigation software: https://opencpn.org/ [7]