So here is my take:
I'm currently working on a SaaS product built on .NET running on Windows Server, IIS, and SQL Server. We're not really a "startup" anymore, but we're still very small. I wasn't here when the first version of the product was built so I wasn't part of that decision.
If I were building this product from scratch today as a money-poor startup, I would probably go with tech stack included Java or Python and PostgreSQL. The primary motivation being cost (as in money).
Each developer is technically required to have an MSDN/VS Pro license (renews for just under $1000 per year). This is not very expensive if you're generating revenue, but if bootstrapping it is not cheap. You could cheat and just share a single license; you definitely won't get caught.
Windows Server licenses, compared to other datacenter costs, are relatively inexpensive. Windows Server has a few advantages; particularly in it's easy to administer and there are plenty of sysadmins out there than know it well.
The elephant in the room, at least for a SaaS product, is SQL Server. The features of Enterprise Edition are so compelling for SaaS (HADR, unlimited RAM, online index operations, compression, and encryption) that it's practically a requirement. But this will quickly become one of the most expensive costs in your datacenter.
But in my experience, SQL Server has some real advantages that I haven't yet discovered for PostgreSQL. The "community" around SQL Server is huge and has a ton of great people who love to help (often for free!). For instance check out http://brentozar.com or http://sqlblog.com/blogs/adam_machanic/.
There are programs like Bizspark which can bring the initial software license investment down to nearly $0. But if you're not generating significant revenue after three years, the licensing costs could hurt.
So like everything in world, it depends. But the bottom line is that, in my opinion, if you're bootstrapping then costs matter and Microsoft products (SQL Server in particular) are a huge cost which have real viable alternatives.
I'm currently working on a SaaS product built on .NET running on Windows Server, IIS, and SQL Server. We're not really a "startup" anymore, but we're still very small. I wasn't here when the first version of the product was built so I wasn't part of that decision.
If I were building this product from scratch today as a money-poor startup, I would probably go with tech stack included Java or Python and PostgreSQL. The primary motivation being cost (as in money).
Each developer is technically required to have an MSDN/VS Pro license (renews for just under $1000 per year). This is not very expensive if you're generating revenue, but if bootstrapping it is not cheap. You could cheat and just share a single license; you definitely won't get caught.
Windows Server licenses, compared to other datacenter costs, are relatively inexpensive. Windows Server has a few advantages; particularly in it's easy to administer and there are plenty of sysadmins out there than know it well.
The elephant in the room, at least for a SaaS product, is SQL Server. The features of Enterprise Edition are so compelling for SaaS (HADR, unlimited RAM, online index operations, compression, and encryption) that it's practically a requirement. But this will quickly become one of the most expensive costs in your datacenter.
But in my experience, SQL Server has some real advantages that I haven't yet discovered for PostgreSQL. The "community" around SQL Server is huge and has a ton of great people who love to help (often for free!). For instance check out http://brentozar.com or http://sqlblog.com/blogs/adam_machanic/.
There are programs like Bizspark which can bring the initial software license investment down to nearly $0. But if you're not generating significant revenue after three years, the licensing costs could hurt.
So like everything in world, it depends. But the bottom line is that, in my opinion, if you're bootstrapping then costs matter and Microsoft products (SQL Server in particular) are a huge cost which have real viable alternatives.