Voiceflow - Build voice apps in your browser without coding
Astra by Cesbo - Talk to Alexa anywhere, from your iPhone
Alexa Skill Kit - Effortless Alexa Skill development with AWS Lambda
Reverb - Use Alexa on your Mac, iPhone and Android
API to bot - Convert your API to Alexa skill or Google Home app in 5 mins
Amazon Blueprints - Create your own Alexa Skill in minutes