I don't understand what is more "safe" about python than for example php. I've seen php used plenty of times for financial applications just like python, ruby, perl, c#,java and a bunch of other languages.
node.js is as solid of a platform for financial applications as any as long as you stick to all the regular rules that an application that deals with finances has to adhere to.
Would I develop a financial application using node.js? probably not. When recently we had to choose a platform for a financial application at the company I work, node.js had a few major shortcomings.
- It did not have solid enough database drivers for sql-server or sql azure which is the database we use. It goes without saying that it does not have as solid orms as let's say C# with entity framework and nhibernate.
- Most of the reference material you will find on node.js on the internet is still lacking. For example most of the material on using databases is on mongodb which was not an option in our case since we did not feel safe using a database that does not support transactions
- Hiring developers to work on your project later on will be more difficult. Since node.js is new there are less developers who know how to use it properly. This means that maintaining developers will cost more and will be harder to replace in the short run.
- No big existing solid financial frameworks to work with, it will be more likely harder to integrate your financial application with other enterprise financial software.
- Most importantly, it did not offer a significant advantage in either development time, maintenance costs or scaling ability compared to the solution we ended up choosing.
Here are some reasons to use node:
- The event based single threaded non-blocking i/o model makes a lot of sense. It apparently scales very well.
- Developing the application using a single language both on the client and server sides is very appealing, you can share a lot of code which saves potential development time.
- The node.js community is very enthusiastic
These are just our reasons, your scenario might be different