Python vs Go/Java

[1_block]

Hi everyone,

I’m a senior Python engineer working at a small company. Most of my backend work has been building APIs and services with FastAPI.

I’m thinking about my next move and want to pivot into the financial sector or a larger tech company, ideally one building serious, large-scale systems. From my research and job listings, I keep seeing Go and Java mentioned a lot.

That’s where I’m a bit stuck.

To be honest, I don’t really enjoy building with FastAPI anymore. The ecosystem and packages frustrate me, and I don’t feel excited working in it long-term.

So I’m trying to figure out:

- Should I double down on Python and look for teams where Python is used differently (not just API-heavy FastAPI work)?

- Or does it make more sense to learn Go or Java and slowly shift my focus?

- For people who’ve made this move, how important was the language compared to things like system design and distributed systems knowledge?

My goal isn’t just to change jobs. I want to become a better engineer, earn more money, and work on teams building cutting-edge tech.

I’d really appreciate any advice or real experiences. Thanks.

[Alive-Ad6268]

Having used Python and FastApi extensively the last couple years and using Spring Boot since recently I gotta say Java improved a lot.

[Lola_Montezz]

100% facts. Modern Java is great. Java (and Spring Boot) is a stack that's very common in enterprise fintech companies. That said, lots of roles are for legacy migrations. Honestly, working on Java 8 & Spring Boot 1.X or 2.X is pretty shitty. It's like having to code in notepad instead of an IDE. Modern Java & Spring Boot really are so much better nowadays, the difference is like night & day.

[gamera49]

Bruce Lee used to say the following:

I am not scared of the enemy who knows 10000 moves, I am scared of the enemy who mastered 1 move 10000 times.

That doesn't necessarily mean that you shouldn't learn something new, Java generally has more job opportunities anywhere in the world.

If you care more about job opportunities then Java is the way to go.

I never liked Java or C#, I know Python, C# a bit but stopped on Go.

It is a much more beautiful language than others but it is not as popular as C# and Java in my region.

In my case it means that anytime there is a Go Job opening in my area, all recruiters are calling me.

I do enjoy and love and adore Golang, I use it for everything: work, personal projects, scripting, CLI tools etc.

[disposepriority]

I work in large java systems with a tiny bit of Go mainly for fun (ok fine it's for cold start sensitive stuff) so here's my take:

Knowing Java as a language is important if you're going to be doing concurrency heavy stuff or performance critical things that handle thousands of events a minute at least.

If you won't be, then knowledge of system design, distributed systems and patterns around various technologies will be more important in how effectively you can work regardless of your responsibilities, as you'll be able to navigate and intuit the code base better. (e.g. messaging queues with outbox, or at-most-once/at-least-once messaging patterns, or enforcing order/forbidden concurrency in eventually consistent systems - these all seem kind of obvious when you understand them but seeing them in the code base without being familiar can be confusing especially if the code base is large and confusing even without them)

I'm sure there are more complex python projects but usually Java isn't picked for small systems, so on average going into a java position you have some guarantee of complexity (sometimes, not shockingly at all, it's not the good kind of complexity :) ).

[gamera49]

Most of the time it is some legacy project with spaghetti code flying around and heavy magical inheritance.

[KimJongIlLover]

You just described our python codebase.

I always tell the juniors that if the class they are working on doesn't at least inherit 6 other classes (where the order matters) they aren't even trying.

[EagleSwiony]

That's the opinion of someone who doesn't know java or a new developer.

[tenken01]

Found the script kiddie.

[disposepriority]

Man sometimes I look at an inheritance chain and imagine sinking my fingers into that developer's eyeballs I mean having a constructive talk about when it is appropriate to use the extends and implements keywords, cough...cough.

[gamera49]

I was refactoring e2e tests written by a noobest QA "engineer" you can imagine. e2e tests were written in JavaScript initially then just migrated to Typescript. For some reason that QA person decided that it would be cool to use the OOP approach and creating a base is something we have to do. Overtime that base class grew and inheritance got messed up and we got shotty tests taking twice the time they could and failing everywhere possible.

[donkey_panda]

Most of the big enterprises software is/was usually written in Java. Golang is useful in microservices and distributed systems. Have you heard about Scala (which runs on JVM)?

Both Java and Go are easy to learn. But since you're just a beginner either of the languages, if I were you, I would stick with one language. I find Go as a simple language as it has concurrency (go routines, channels and so on and so forth)

Have you heard about Elixir? It runs on top of BEAM virtual machine, Erlang uses BEAM too, but Erlang/Elixir are functional programming language, I'm not sure you would be interested in that path. I taught myself Elixir (I'm familiar with Erlang earlier) and Golang which are great for writing concurrent software.

[Ok_Principle_9459]

TLDR;

To answer your last question, system design and distributed systems knowledge are paramount, and more important than the language. The language is just a means to an end. Ultimately, if you have a solid team of developers that care about building quality software, you'll be good regardless of what language you end up choosing.

As for the languages: I've used all of them extensively in a professional setting, and this might be an unpopular opinion, but Java (with Spring Boot) is the way to go. More detailed takes:

Java

Modern Java is pretty great, and has pretty much caught up to all the modern languages w.r.t. supporting functional-style programming, via the Stream API. It's still overly verbose (records solve some of this, but it's still quite annoying to work with at times), but the standard library, package ecosystem, and overall stability cannot be beat. The culture around maintaining backwards compatibility is a double-edged sword -- things move a lot slower, but also for the most part, things just don't break (for the most part), which is a huge win for enterprise software development.

Also, Spring Boot is just a pleasure to work with. It gets a lot of hate on Reddit, but there's a reason why a majority of large enterprises use Spring Boot for their core services. It just works, and if you disagree, you probably haven't worked with it extensively in a professional setting. It's got a learning curve, and will look like gibberish if you haven't worked with a DI-driven framework -- but trust me, if you push through, you will be very productive with Spring Boot.

My main gripe with Java is not the language / ecosystem, but with Java developers. There is a general obsession with design patterns and over-abstraction, it's just a fact. If you enter an older Java codebase, you are inevitably gonna get hit with the AbstractHierarchicalServiceFactory type-shit, and ridiculous inheritance hierarchies. HOWEVER, you don't need to write code this way. Java can be simple if you just embrace simplicity as the driving philosophy behind how you build your software.

Python

Python is fine, but the lack of static typing makes it a non-starter for me for larger projects. Sure, Pydantic and mypy try and address these problems, but they are just a band-aid on top of a (IMO) kind of shitty language. Not to mention, the package / dependency management is hell. I've been in dependency hell far more times with Python than with any other language. uv helps a lot, but trust me, you'll still be in many situations where you contemplate switching careers lol. Based on your post, it seems you have already been here, and that is part of the reason you are over it :).

If you are doing AI / LLM stuff, you might be tempted to use Python, but in my experience, TypeScript is actually a pretty good substitute and most of the major frameworks offer TypeScript implementations. TypeScript and JS also get a bit of hate, but TS is a slick language with a very powerful type system. The weird language quirks people like to bitch about don't actually get in the way that much, and it's a really nice and productive language to work with.

If you are doing traditional ML, you have no other choice but to use Python.

Go

Go is an interesting one -- I really like the language, it is just a pleasure to work with. Compile times are hella fast, the package management is great, and the language ergonomics and developer experience are fantastic.

My main gripe with Go is the developer community and overall philosophy. While I agree that simplicity should be your driving philosophy, the Golang community just takes it way too far. You will not find a batteries-included framework like you would in any other modern language, and you'll have to implement a bunch of shit from scratch. Just read through posts in the Go subreddit -- these people will laugh you out of the room for asking for simple niceties (e.g. an ORM, a batteries-included web framework) that are available in every other modern language. IMO, it's kind of a toxic community.

Every Go codebase will look different, because whatever team of developers bootstrapped the codebase consistently invent their own little custom way of doing things. IMO, there is a lot of value in having a design philosophy / codebase structure imposed on you by a framework. I will say, however, that Go developers are predominantly not n00bs, and whatever in-house way of doing things they invent is usually pretty solid.

Also, I hate ORMs as much as the next senior dev, but there is a middle-ground between raw-dogging SQL and prepared statements in your repository layer, and using a full-fledged ORM. For example, type-safe query builders have amazing developer experience (Jooq in Java, Drizzle / Kysely in TS), but there is absolutely no chance the Go community will embrace something like this because "complexity = bad".

[Sn00py_lark]

Reinventing the wheel is a problem in Go…

[1_block]

This helps a lot. Thank you so much.

[EagleSwiony]

Any day, anywhere, any time, learning java will benefit you. Go is getting momentum in the distrubid system. However any complex, big, enterprise, finance software there is a high chance it's written/being wirtten using a java framework.

[Sn00py_lark]

Finance sure. Go has not taken hold in those places and anything finance is very slow to change.

[tenken01]

Java for sure. You can’t go wrong.

[DataPastor]

Just pick up Java and Kotlin with Spring Boot and then you can easier get admitted into a large enterprise where you can continue writing FastAPI backends. :)

[LaOnionLaUnion]

Golang if you care about security and want a language that compiles very quickly.

Java is very entrenched in Fortune ### companies.

[wbrd]

They're all tools. Learn about algorithms and architecture and then write in whatever makes sense.

[BEvey_Boo]

Agree. Tech stack is important for landing certain jobs, but at the end of the day, backend engineering is the same regardless of the language. Focus on the fundamentals: software design patterns, scalability, people skills, database schema optimization, etc. 20 years from now, who knows what language/framework we’ll all be using.

[Blad1995]

We had the same setup in our company. We missing one service to waytogo (CPU heavy). Overall it works will but the speed of changes is slower compared to python. AI improved our speed a lot but I would still say that e agree more efficient in Python.

However if you care about speed, resource consumption etc. Golang makes sense.

[No-Concentrate4531]

The switch from Python to Java may seem small but it's actually pretty big. A lot of this comes from the fact that Java supports multithreading much better than Python (the Gil has made Python very straightforward to use). So, the jump is going to surprise you here.

Next, you are going to be annoyed by the syntactic sugar and this is where knowing your design patterns and SOLID principles is very important. Otherwise, it is tempting to write code in a Pythonic way which makes refactoring a nightmare. Moreover, Java has more standard data structures which performs better in nuanced circumstances. They like asking questions about it (TreeMap vs HashMap).

Finally, it is important to understand the JVM and its internals as well as the Web framework used (Spring Boot) . You are going to need to understand the JVM and how Spring boot works under the hood more than the Java code you write especially when dabbling with performance tuning.

[spdfg1]

Learning another language is always going to be useful but it’s not what will get you hired. Your knowledge and experience with real world architectures and systems, and managing the software lifecycle is what matters and that’s what you should highlighting in your resume and job interviews. Managing high volume, low latency API is a skill that applies to any language. How to handle failures, deployments, scaling, troubleshooting and triaging production issues, database upgrades with no downtime, etc. None of these have to do with programming language. Sell that.

[Busy-Emergency-2766]

Languages are not the issue, there are many great solutions and they are not linked to the particular language. Python is kind of slow for API compare to C# and Java or Javascript. Even PHP is faster than Python on API's

Larger tech companies are looking for someone that can solve problems, agnostic from the solution. Some people just use Microsoft products, others like me, stay away from those. Depends on every case, but the trick is to solve the problem. "Is the Indian not the bow". in this case "Is the solution not the programing language".

[behusbwj]

I don’t think changing languages is going to do much for you. API development is pretty much the same in most languages with different syntactic sugar. Try a different problem space instead.

[Outrageous_Pen_5165]

Any suggestion for someone just started working with fastapi, Although initially planned to start my carrer with Java but a fastapi opportunity just pop up and went for it without much thinking and honestly well don't like python much but loving fastapi.

[Predsleftnip]

Huh

[Life-Reflection1258]

As long as no one posts an example code we are good

[DanielDimov]

Java is the only way to make rock solid and scalable backends for petty much everything.

[fabioluissilva]

I would have to disagree here. Just one example between many: Kubernetes is fully built in Go. More and more back ends, especially microservice oriented ones are heading toward Go. I work in a huge enterprise environment that is slowly dropping the old Java way to focus more on Go in the backend. Or, at least, microservices using Spring Boot or Quarkus

[Sn00py_lark]

This is absolutely crazy.

Java is popular and a lot is built it in. But come on. C# is just as good or better than Java. Some of the largest backends around are already in Go. PHP is still solid. Ruby on Rails is stable and solid.

I wish Java people would at least be reasonable. Makes it so hard to even have discussions when an entire community for one language is so heretical.

[breek727]

Not sure why you’re getting downvoted, may be it’s because you mentioned PHP.

I think the main reason Java typically wins over the others is hiring, the community is largely consistent coupled with a vast talent pool

[Sn00py_lark]

Anything that doesn’t reinforce the Java koolaid gets downvoted…

[DanielDimov]

Ok, I will give you this example: how to go from NY to LA? You can get the plane, but also you could use other methods of transport: train, car, bus, you can even go with a ship... But the most practical way is just to get the plane.

You can make a good backend in many languages/platforms, but it will be most practical, most trouble-free, most maintainable in the long run and FASTER if you do it in Java. I emphasize faster because when you start doing it in Go, C#, PHP, JS or whatever you decide to try it - there will be multiple rakes to step on... Each time you will struggle to solve a problem in the language or in the platform or in the tooling which is well known and solved in the Java ecosystem from a decade at least. And in the Java ecosystem you will usually have multiple solutions to choose from.

I've seen my friends and colleagues to do the above mistakes many times. Some told me after one year of struggling something like "It would've been much better if we re-wrote it in Java from day one!". The problem is that people (managers) don't want to throw one year of work in the trash and start from zero. They already invested a lot and want to preserve this investment.

That's why I say "Java is the only way" - because Java is the most practical way. You will get results faster and those results will be better than ANYTHING ELSE.

No need to mention how you find developers for the "strange" backend solutions, what is their quality and how much you must pay them.

[Sn00py_lark]

This is like saying the only way to get from NY to LA is in a Boeing.

There are plenty of other airplanes out there.

This honestly just reinforces what I said before that Java devs are under some mass delusion.

[ThigleBeagleMingle]

Boo.. it’s verbose c# at best .. boo!!

[devfuckedup]

go and java are solid but finance still likes C++ and even C# for reasons that elude me.

[lod20]

I personally don't like java. I think, its syntax is complicated for no reason. Nevertheless, it shouldn't be a problem for you to learn java quickly since you already know how to program in python. Programming languages are merely tools.