Great developer team with a good mix of experience (seniors vs. juniors)
Consideration of developer preferences and learning goals (you will achieve better results if you like what you do)
Very good and up-to-date tech stack (ELK 5.x, Redis 3.x, Postgres 9.x, MongoDB 3.x, Play 2.6.x, Java 8, React, Angular, Spring, Docker, Ansible, Jenkins, GitHub, Slack, AWS, ...) with opportunities to add more (e.g. Kafka).
Very interesting development challenges (high traffic application, movement towards microservices, business intelligence, machine learning, RESTful APIs, Partner Integration, ...)
Full cloud infrastructure on AWS with the possibility to manage your own servers for your application if wanted and needed (self responsibility).
A lot of monitoring (ELK) to see the health and the status of our applications.
Already quite some legacy code with no unit tests, but we are cleaning it up and writing more tests + we are moving towards microservices which are written much cleaner from the beginning.
All the pros and cons of a startup :-)
technology stack, development challanges, development team
legacy code, unit tests