Alternativas ao ahrefs para Software as a Service (SaaS) com licença gratuita

• Software as a Service (SaaS)
  Todas as plataformas Windows Mac Linux Chrome OS Android iPhone Windows Phone Blackberry Blackberry 10 iPad Android Tablet Web Software as a Service (SaaS) Firefox Opera Safari Windows Mobile Chrome
• Licença gratuita
  Qualquer licença Licença gratuita Licença Open Source Licença comercial