The company is constantly and deliberately understaffed. Even though your pay may be not the worst, as a software developer you’ll be doing at least a 3-person job - you’ll be a developer, project manager, and user support specialist. There’s pretty much no planning, things are done in a hectic way, it’s often unclear what needs to be done to move forward with a task/project. Optiver is a noisy and distracting workplace, it’s considered ok to have loud conversations when others around are trying to concentrate. There’re very limited options to work from home or away from desk, you won’t get a laptop or decent phone. While I worked there, there was a major reconstruction of the office being done, both outdoors and indoors. During that time sometimes it was virtually impossible to concentrate - there was loud sound of drilling, toxic smell of paint or burned plastic, extremely low temperatures during winter, even workers listening to radio during office hours... The company didn’t do anything to minimize these inconveniences, probably breaking quite a few workplace laws in the meantime.
The technology stack they use is very limited and outdated. There’s no room for trying out new things in tech; they constantly emphasise that they’re a trading, not a tech company, and technology is just a tool to accomplish the business needs. They have pretty much non-existent IT support, you have to figure all out by yourself and the developer machine setup is very inconvenient.
Projects in some teams can be interesting if you’re lucky but there’s also a lot of work done due to regulatory requirements or for ‘political’ reasons. The company is very hierarchical, even though it’s advertised as having a flat structure. The teams, instead of cooperating, often are very competitive against each other; between different offices (e.g. Amsterdam and Sydney) there is pretty much no cooperation at all.
They are quite obviously favorizing Dutch employees; even though the Dutch comprise quite a bit less that 50% of the staff in Amsterdam, somehow the vast majority of team leadership/managerial positions are given to the Dutch.
Overall, maybe it’s not the worst place to work and you can definitely make an impact there, but all the cons are just too much to make you want to stay there.