Ask HN: How to switch from front-end to back-end

First start by defining "backend". It means something different depending on the size of the project. Many systems now are three tier meaning front-end, middle-tier, and backend.

What you probably want to focus on is the middle tier. In those three tier systems the backend is actually very low level (data processing, storage, replication, message brokering, etc) and is often handled by third-party products such as database engines.

Some (many) projects combine backend-and middle tier as if they are the same thing. And in some systems the middle-tier is very thin and just slightly abstracts the backend.

So definitions aside... if you want to transition to middle tier...

- Learn API development. Especially focus on REST and possibly GraphQL. Learn the difference between a 422 and a 401 error, GET/POST/PATCH/PUT etc, etc.

If you want to really get into backend...

- Learn hardware limitations

- Learn Linux very well

- Learn about job queues, Message busses, and interprocess communication

- Learn about service discovery and the differences between eventually consistent and strongly consistent

- Learn about containerization

- Learn about system operations

- Learn algorithms. Including graph algorithms and how to determine algorithmic complexity

Useful for both...

- Learn SQL

- Learn a few NoSQL systems... MongoDB, Elastic Search, Redis

- Learn about security

Don't worry about specific languages. The concepts carry over to any language. If you have to pick, Node.js, GoLang, Ruby, and Python are all acceptable choices for middle-tier.

And don't solely rely on node.js as a backend. It can be a gateway to backend dev but not the best option out there.

Thank you for advice!

Actually, I know that language is not that important, but as I said, without prior experience, I am afraid that if I will market myself as just a "backend/software developer", companies will be afraid, and with a single language it seems easier.

So, the best way just to pick a topic and go deeper, there are no resources that cover them together?

Backend is full of rabbit holes.

So build something simple (blogger) which touches on primary concepts : api-router, auth, access control, storage, db, cache, cloud, tests, continuous integration & deployment. Even for a small app - one will have to make lot of choices from existing components/frameworks/packages. So begin in a language you are comfortable or you like to get a hang of concepts.

Personally I would pick API development and go from there.

Decide you want to build a REST API, design it properly (it is easy to make a not-really-REST API), write unit tests, and build it.

I think this answer kind of puts the cart before the horse.

I've been doing backend dev for many years and my perspective is that it's better to dive in and learn things as you go along.

Yes, all of these pieces listed above are important, BUT if you focus on learning each one well, it'll be a long time before you actually ship backend code. You don't need to understand things like containers, deployment, queues, distributed systems, etc to just start.

I'm going to take an opposite approach and say that the best way to get started in backend is from the top of the stack. Build a simple web app or API, for example a journal or bookmarking service.

Language and framework choice don't really matter at this point. Fundamentals are not radically different across them aside from the biggest difference being asynchronous vs synchronous paradigms. Start simple.

Just to clarify, I was not suggesting someone needs to learn all of this before they get started.

Although having a meaningful product with either knowing most of this or having a mentor who can help and/or potential write code as well is difficult and you will en dup with a lot of technical debt and or problems as the product grows.

Define "middle-tier". The difference between backend and frontend seem pretty clear to me in the case of web services. Some code is clearly executed in the client's browser, and the rest is not.

You can perhaps use "middle-tier" to be more specific about which aspects of development you mean, but there's no use in fuzzing what is actally a very clear and helpful distinction.

Honestly if you want to get out of your comfort zone and really start thinking like a backend developer, I would recommend using a solid, proven platform like Java. Specifically you could start with Java 8 & Spring Boot.

The differences between frontend & backend: frontend code tends to be more loosey-goosey, less robust. Generally the goal of the frontend coder is to write lots of features in a short amount of time. Backend development is more "slow", you still want lots of features, but they need to be robust and work correctly 99.99% of the time.

For that reason, I think the best way to think like a backend developer is pick a language that doesn't have dynamic objects (like Python). I'm not saying that Python can't work, I'm saying that using a static-type language will help you outgrow any sloppy thinking habits that people tend to get when they spend too much time in Javascript.

Hiring wise, Java is still a very in-demand skill. Tech wise, Java is an extremely stable and proven platform that will serve any project well. It's "boring" technology (which is a good thing). If you really want to change your thinking, then try to stop gravitating towards shiny things and instead use a "boring" platform.

I agree. Java might not be sexy but there is a huge marketplace for java devs. The nice thing is that you don't have to learn a new framework every week. I learned Java in 1998 and spring in 2005 and I still rely on that knowledge today.

I'd second this and throw the idea of jumping into C# and .NET. The .NET platform is about as common as Java in back-ends, and seems to be evolving at a more aggressive pace. C# is pretty great, and once you become familiar with .NET as a whole it's pretty easy to gain skills in VB.NET and F# if those interest you.

Is not it too enterprise'y? Is it possible to find small (~100 devs) company using .Net and C#?

And also, how much it will take to achieve some decent level (to be able to work as a middle dev)? I think with Python 1year should be fine, what about .Net?

There are tons of of them. Might not be flashy but they're definitely out there. A lot of B2B software is Java/.Net.

It's not overly enterprise driven at all, from my perspective. The company I work for has teams totaling to about 40 or so developers and we're completely MSFT driven. From the DB side of SQL Server to web/backend of ASP.NET and .NET. And my understanding of the industry is we're hardly alone. In my area (the southeast US) there's plenty of opportunities at similar sized companies or smaller.

Achieving an intermediate skill set in any language/platform will certainly take more than a year. The language itself takes very little time - but picking up maintainable (Clean Code, Pragmattic Programmer, etc) habits takes a good bit longer for most people. Python probably has more beginner resources available thanks to MOOCs and the like, but there's plenty of .NET intro sources as well.

Funnily enough, most companies I have worked at has much better frontend code than backend...but maybe that's a problem that tends to come with smaller companies if they're not hiring the right engineers, and not so much a frontend vs. backend thing.

As for advice, find a company hiring for full stack engineers and bill yourself as someone able to learn on the backend. The company also has to be one willing to take that chance. Do not get sucked into the debates of x vs y language, and be willing to adapt to what you're working with. If your credentials are strong, you may have more wiggle room to be opinionated.

Edit: Just to add, I also transitioned from frontend to fullstack, although now I'm in the hybrid land of engineering management with coding being a bonus tool for assisting with management. My company has helped multiple engineers with primarily frontend experience transition to fullstack work (or in the case of some, even exclusively backend work). I honestly think it's not worth fussing about languages, as those can be learned - even SQL. Understand your fundamentals, and make sure you present yourself as a flexible person willing to put in the time and effort to learn and you will likely succeed in a transition.

Also I recommend avoiding being desperate to switch when job searching in such a transition - few things smell worse than the stench of desperation, which will affect your pay & negotiating wiggle room.

Yeah, that's true about both Java and .Net, but what I am afraid, is that these areas are too "enterprise". To be honest, I am leaning towards more small companies. I like .Net Core project, but again, I am afraid that I'll end up in a big corporation with pretty boring stuff. Also in corporate environments it seems that there is a lot bureaucracy, which I don't like at all.

But yeah, in terms of stable and proven solutions it is extremely safe place.

Try using Django (Python) for a little while. You'll get exposed to everything you mentioned because the Django core is feature rich. There's a lot of support for Django—it's battle-tested and used by a large community of Python developers. Out of the box, Django is a lot heavier than something like Tornado or Pyramid, but if your goal is to work with a widely used framework with lots of backend features to learn, I'd choose Django.

Yeah, that's a good one. What would you recommend to focus – Flask or Django (or maybe Tornado), given that I like to wire stuff by myself (so I enjoyed building an API in Golang)?

I'd go Django first to understand the basic terminology, concepts, and patterns that are used on the backend. Django is old, but feature rich as the parent said, yet still heavy development and use. So the ideas and concepts you'll get from it will still be very valid.

Than as you get comfortable you can branch out into the less meaty frameworks like Flask or Go ( if you want to call that a framework ).

Remember, beyond the actual application server and framework, there's all the other 'stuff' that goes around it. The web server, databases, caching technologies, etc. Take the well travelled path first to see the best practices, than go your own way if you really do want to 'wire stuff' yourself. ( And trust me, even with Django there's plenty of wiring required still to build a real app ).

I would recommend Bottle.py, it's super easy to get you going. But the advantage with Flask is that you have more code to learn from and its arguably more adaptable. Django is good for bigger stuff, it's too heavy for hobby stuff and microservices.

When you're just starting out, it probably doesn't matter too much. Pick one, and pick a project to build using it. You'll learn lots no matter what language out framework you use, and most of that knowledge will be portable to other back end languages and frameworks.

Maybe do something like building yourself a personal Pinboard clone. Or your own personal Twitter clone. Or anything else you'd like. Deliberately just focus on bare bones functionality. No fancy extras.

And no JavaScript. Make sure your project works without it. You can add in JS later in if you really want to, but worrying about it now will just take your focus away from developing back end development skills.

Depends on your priorities for learning.

Pick Django (+ Django Rest Framework if building an API) if you want to take advantage of its many abstractions, build features and ship fast.

Pick Flask if you want a small, simple codebase that's closer to the metal. You can learn more this way but it also takes more work to ship the same app in Flask vs Django IMO. One example is the Django ORM is much more intuitive and simpler to get started with than SQLAlchemy.

Django also has incredibly well written and complete docs. The best of any web framework that I've seen.

I'm currently a full time API developer using JS (Node), SQL (MySQL), and Ruby (Rails) and whatever is needed for each new project.

- My initial experience with "coding" was MySpace (HTML/CSS) which led me to learn/experiment with JS.

- Rails got me into API development because of all of its "magic" (even though now I'm less about magic by far); but it was a step.

- Having experience with HTML/CSS/JS made Rails easier as far as getting something up and running because I already knew what my views should look like and how to get them there.

- This allowed me more time to experiment and get to know Rails, leading me to discover a lot of terms and concepts I had to become more familiar with i/e cacheing, server-side rendering, deadlocks, data-layer, and the list goes on forever.

- I realized the best thing to be great at, in my case, is SQL because persisting and extracting data the way you want/need to goes so far in making other things easier.

- Finally, I started learning how to truly develop architecture, queues, schedule, etc once I got a job on a team where my peers and supervisors were willing to teach me.

Hope some of that helps!

I don't think you can go wrong with Python. I can't say one way or the other about Go.

That said; it seems to me (as just one dev's opinion in the U.S.) that Europe -- particularly northern Europe -- has a pretty healthy Clojure scene. Of course, it's not going to compare to Python/Ruby/JS in # of jobs, but if you liked it, I can tell you it only gets more fun as you learn more.

One general piece of advice -- internalize this: https://gist.github.com/jboner/2841832 (latency comparison of different operations) as one or two operations at the wrong layer will overwhelm a whole lot of algorithmic cleverness.

Thanks! Very helpful gist.

The problem with Clojure is that I am not very proficient in JVM (actually, I know very little about it), and I know only basics (like create a simple REST CRUD), so I have some doubts that I'll end up getting job just studying language and platform in the evenings.

I would be hesitant to aim anyone's nascent development career at Clojure. Not that there's anything wrong with the language, but I think we've passed "peak Clojure":

https://www.google.com/trends/explore?date=all&q=clojure

You've received some wonderful advice about some specific technologies that you should focus on. In particular, the advice to develop strong database skills is going to be particularly helpful.

I want to add that because you're experience on the front-end, your transition to the back-end will be a little easier. The best way to learn how to design an API is to consume many of them!!

Also, since already have front-end experience, you may find it easier to transition from front-end -> full-stack -> back-end only. Your front-end skills will be considered full-stack experience and when you're in a full-stack role, you'll have an opportunity to learn some solid back-end fundamentals!

Good luck with this!

If you're familiar with JS then arguably the easiest transition route for you would be to start building some node based services on the back-end.

It'll allow you to get to grips with some of the gotchas you get with back-end development with an ecosystem you're already familiar with, once you've conquered those you can then start branching out to other languages and frameworks pretty easily with a solid understanding of back-end principles.

Another benefit of this approach is there's a huge demand for JS engineers who are comfortable on the front and back end at the moment, so it sounds like you're in a great position to spread your wings.

Yeah, basically we don't have node.js microservices, but sometimes I add endpoints to our node.js server with server-side rendering.

Also I am trying to create my side projects, but as I said, I suffer from not solid knowledge, so I feel that I am doing some wrong and unnecessary work all the time.

What is your goal?

If you want to land a job as fast as you can, you should get a team-enabling language like Java.

If you have some project you want to get done but need backend knowledge for it, go with a mature high productive toolset. Choose either Python+Django or Ruby+Rails and grow from there.

If you want a new area where you can have fun and learn new stuff, go wild with non-mature high learning curve tools like Closure or something even less mainstream.

If you have some very specific requirements like high availability, high concurrency, or whatever, ignore everything above and choose your toolset based on those.

I want to change my current development role and put myself into different position to the end of the year. I want new challenges and I want to try to work in different environment – from sandboxed browser to real servers (or containers), with different security model in my head, to work with databases, and I'd like to work with distributed system as well.

So much stuff, so little time.

I think you should take a VPS, one of (Django || Rails), do a small project all by yourself, and decide if you want to go deeper on any of those things. The alternative is to learn Java and go quickly into an entry-level job, but you won't be able to choose what to learn by doing that, besides the small project will help you learning Java too (but may make it unbearable).

> you should get a team-enabling language like Java

Note that if you want to work for a startup, Python, Ruby, or JavaScript are much more popular languages today than Java. You can iterate much faster in Python vs Java.

I went front recruiting w/an MBA to backend, so I'm pretty sure you can do it, too :). Not sure I have any generically useful tips beyond spending more time doing backend stuff. Write an API that a frontend can talk, figure out how to deploy a Docker container, learn SQL, etc. Backend is a pretty broad term that just means "not frontend".

Happy to chat 1 on 1 if you like. Email in profile.

If you already know frontend programming fairly well, why not going for Node/Express and re-use part of what you know? You will just have to study new coding approaches without having to change language as well. Once you learn how to write APIs in one language, switching to another one is pretty simple.

To be honest, I'd like to avoid Node.js train at all. Of course, I have some experience creating server side rendering and adding small features like authorization, but as I said, I'd like to dive into different communities and change my environment.

All I can say is to learn the spec. Like how REST works and pick a language and go deeper into it.

If you want to be on the safe side, go with Java.

It's there and will never die.

You are right with FE technologies keep popping up. But you will have the same issue in the BE. New BE technologies are born to solve a different problem space such as scaling, performance, or things of that nature where as FE is more focused around HTML, CSS and JS.

Overall, learn generic concept which are transferable regardless of stacks such as NoSql db such as mongodb, Relationship db such as oracle db, caching with Redis or memcached, message queue such as kafka, text indexing such as elastic search, stream processing such as storm, batch processing such as spark, and a ton of machine learning.

With that in mind, BE is aslo rather bloated, but it evolves around more area of concerns and not just CSS, HTML and JS

Learn how is composed a request, how to build it and how you read it. Iterate on architecture rather than on features. Try out all of them, take only what you need from them.

Check out and learn how to use Docker and the docker-composer ; Check Python & Ruby, choose to one you prefer. To me they are really great for database management (migrations) and administration; Lot of big websites use it in production.

Learn how to use a cache and understand why it is useful.

Check out GoLang and build your self a simple server. (Auth is great for a first approach of golang, i've been on it this week and everything is pretty much worked out by public libs) ;

Get back to SQL

Given that you are familliar with Javascript already. You can pick up nodejs easily. Using nodejs for a while will give you an idea of what backend development's daily life look like.

Once you understand the common tasks that are involved in backend development, it will be easier to switch programming languages. Python is a good choice for example, it is very versatile and has been used to program various backend server. It is also being used extensively in scientific computing, machine learning and etc.

Yeah, basically I can use node.js almost instantly for writing actual backend, but as I said I'd like to avoid it. I want to broad my programming horizons via using new language, new environment and exploring new community – I know, all of this is possible via side projects and open source, but it is still a different thing.

While I don't have your expertise in front end development I share your sentiment and I, too, find myself prone to backend development than anything else.

Python is a great language used often in systems programming. It's also a joy to code in.

Rust is intriguing is check it out. The build and package system is robust.

Go is great, too.

Basically you're on the right track. Now maybe just do some study on concepts like paxos or the CAP theorem. You might look into databases both relational and not as back ends often involve those.

Yeah, actually, I listen to some podcasts, and one of them touches distributed stuff pretty heavy, so I've heard about quorum, consensus, paxos, etc. But it seems too heavy, so I think it is much easier to enter the market through fullstack/API developer. Same story for cloud/infrastructure – I hope to go into not very big company and to touch all of this stuff.

Which one? I'm looking for one in that space.

I spend most of my day listening to podcasts. I'm glad I found them again.

I like the changelog, talk python to me, python bytes, Mac OS ken, the packet pushers network (networking centric even though I don't know much, Greg Farrow and company are hilarious), and software engineering daily and programming throw down, to name the ones I know off the top of my head

By learning a real programming language?

Well basically that was a joke, however a lot of stuff is different on the front end than on the backend. Not everything has a main event loop and async programming is not really there in many spaces. Depending on what you are doing you would need to learn a whole new programming concept, which is not that far off from my initial statement.

I would say Node, Ruby, Python should be the easier for you to get started.

Node: you already now JS, the ecosystem, and the idiomatic ways to do stuff. You can focus on the differences between FE/BE

Ruby: It's easy to learn, also dynamic typed, and Rails it's a very good technology to start with backend/MVC

Python: Also easy to learn, also dynamic typed. I never played with Django..

You ought to ask yourself "which database do you want to learn". Make sure database transactions, consistency etc. becomes your native tongue. Being familiar with SQL and Postgres (or similar) is just as, if not more, important than Erlang vs Python vs Go.

So, should I know the details of how, let's say, PostgreSQL works, or just normalization forms with effective analyzing of SQL queries is enough?

I know the basics, but how deep should I go, if I want to be a serious developer?

Once you make a pick of Postgres, you can go as deep as your free time allows you to.

Make sure you know about database transactions and the various ways they can be configured and what effects it will have on data consistency. That way you will not make code that seems to work but which randomly corrupts data. That is the most important thing of all.

Beyond that I would go with learning what you need on whatever job you get, just be aware that choice of DB is just as fundamental as what programming language is used to a backend project.

As a front end guy (I started as a graphic designer, learned HTML, then JavaScript, then Flash/ActionScript, back to jQuery, Backbone, Angular 1) who moved to backend, my advice is - pick anything that you feel comfortable with.

You have several planes of "moving to backend" and I will try to go over them categorically

1. Language: not a critical choice, but since you come from a JS background, I would stay with JS. I'd start by deciding to focus on NodeJS and that ecosystem. I wouldn't switch to Go/Python unless you have an urge to learn a new language. Moving to backend dev has many aspects to it. New language is not the most important one. Few aspects of languages do matter though, you have "lightweight threads" in Go (channels), but not in Java (unless you use Quasar). Node is not exactly multithreaded in the literal sense of it. Each language has it's own abstraction around async computing, Scala/Akka futures and promises slightly different than Java's futures and promises, which are highly different than JavaScripts Promises.

2. Paradigm. learn both best and bad practices, patterns and antipatterns. Good to know some GoF design patterns, but also learning about functional programming, immutable design, reactive framework (RxJS for example). You will find out some of the front end philosophy is there in the backend too. Good design, OOP or Functional, has similar principles (single responsibility, loose coupling)

3. Databases If you want to do backend, you'll most likely need to have an understanding of how databases work. From basic RDBMS principles, transaction isolation, ACID principles, to NoSQL, CAP theorem, Big Data etc. Learning SQL, Hive dialects etc is in my opinion an integral part of backend programming.

4. Security - you must understand a lot of aspects in security, from why not use MD5 to hash passwords, what is a salt, a pepper. what is Kerberos, client SSL, and why we should stop saying SSL when we mean TLS. Why you should never use DES, why you should rather not store passwords in Java as Strings but rather as char array. How to sanitize user input, and do server side validation, preventing XSS / SQLI. What is CSRF and how to handle it on the server side. What is cookie based authentication, vs JWT. SAML, OpenID, Oauth principles. etc etc. Security must be baked into the process from start to end.

4. CS - as others have mentioned. Basic data structures and algorithms is a must.

5. Some basic OS stuff. you should know what is a page fault, virtual memory, and how OSs work in general. Caching and distributed caching, caching invalidation etc. Unless you do graphics on chips or something, then eliminating branching using bit twiddling is something I would skip... also cache alignment, unless you really are doing some really realtime stuff.

6. Learn architecture, especially, microservices, serverless, SOA, monolithic, 3 tier, what is a 12 factor app, what is distributed computing etc.

7. Learn devops and infrastructure, whether its on prem, AWS, GCP, or Azure, learn concepts such as infrastructure as code, CI/CD, configuration management, Puppet/Chef/Ansible. Docker and containers, Kubernetes, Mesos. This includes learning command line.

8. Learn basic networking. Don't lower than level 3 if not needed, but know how the network works

i always think, each one require a lot of knowledge, but it's easier change from front to back, depends of the language

Not a fan of Python, but its vast ecosystem of libraries makes it a very pragmatic solid choice.

I think you might be suffering from a grass is greener situation. The web development community as a whole is unfortunately very obsessed with new an shiny. New frameworks and new languages come up fairly regularly and people jump all over them assuming that they are a solution to their problems. I think this reflects the fact that web development has the lowest barrier to entry of any programming field (there is a ton of demand and it's relatively easy to write basic things like WordPress modules or whatever) and so young and inexperienced developers flock to it. (Which is not to say all young people think this way but I think it is more common among inexperienced developers.)

Personally I find that the way to avoid chasing new and shiny all the time is to work for a good organization that recognizes that is not the best way to have a stable and solid codebase.

In other words, I think the solution is not so much the position you have as far as front end vs. back end but where you are working.

Personally I feel it is not really about "grass is greener situation" (though of course it contains part of it). What I want is to be a better developer, to learn new platform, to get familiar with Linux, with processes, with infrastructure and so on.

Working as a front-end developer, you are pretty isolated, and while it is possible to communicate with other departments (what I do), it is still seems like a different level.

So I want to shape myself as a better software developer, along with trying new field.

If you want to really learn Linux and infrastructure stuff then you should become a systems engineer not a back end developer. Back end developers rarely become experts on those topics, since they are at least one layer beneath our area of concern usually. Even if you are working at a small shop chances are you will outsource those kinds of concerns to a hosting company like AWS.

Nearly every new programmer starts in the UI. Then, when you discover how annoying that can be, you CLAW your way out of it. I would recommend you know a backend language such as Java, .NET or Ruby. Learn it well.

Java and .Net both seem too enterprise. I'd like to make the transition during the year, so is it possible to get a job despite not having experience in such fields? Scripting/"Startup" languages (like Go, Python, Ruby) seem much more easier to get a job with not so solid experience.

Be careful about that enterprise assumption. I've worked for two startups in my career. The first used mainly Java, and the second used mostly .NET.

Heck, lots of companies you'd consider to be enterprise are building cool projects with React and Angular 2 front ends hooked up to Java or .NET on the back end. Projects like those might be a decent way for you to leverage your current experience and work your way toward back end development.