Updated: May 10, 2021

Some people say that the best programming language is the one that the developer knows best. This is a joke, but there’s some truth behind every joke.
How to Choose the Right Language for an IoT Project?
When choosing tools for the execution of a certain task, we should always consider programming languages in relation to technologies because technologies are the basis for the development of various software types. And the technology chosen imposes requirements on the choice of language.
For example, if you are developing a product using blockchain technology, you may choose the Ethereum platform and write smart contracts in Solidity. Or you may choose the Hyperledger Fabric platform as a blockchain framework implementation, and Go or JS as the programming language for writing smart contracts. However, other programming languages, such as Java, can also be used.
To build a roadmap for your project, you need to decide which technologies to use for product implementation. If there is no rigid binding to one technology, the choice should be made based on the following factors:
Undoubted popularity — not trending, not hyped up, but the technology with a stable and positive reputation
Regular version updates
Good technical support and up-to-date documentation
Large online community
The right choice will allow you to find a team more easily and cheaper while ensuring that you can always find more people to develop or maintain your product if necessary.
Talking about IoT development, we can divide the project into three parts:
The firmware
The back-end part of the project
Client applications
Let’s talk about each part in more detail, based on the issue type.
Firmware Development
If your device has a board like Arduino, then most likely the firmware will be developed in the built-in C-like programming language. Everything is simple and clear enough then. You will need a developer who knows the syntax of C programming language (and almost any developer knows it) and preferably has experience in programming such devices.
But if Arduino’s capabilities are not enough for your product, you should consider more advanced systems like Raspberry Pi and its analogs. These systems usually have the Linux operating system on board, but you can install Microsoft Windows if you wish. This means that firmware development is possible in almost any programming language — Python, Java, Kotlin, Ruby, JS, or PHP. Python is the most common programming language for these purposes. Let us, therefore, pick out the top 5 languages for such projects:
Python is the most common language for Raspberry Pi. There are many examples and ready-made solutions on the network.
Java is one of the most popular programming languages in general and for IoT projects in particular.
JavaScript is the most popular programming language, according to GitHub and Stack Overflow. It is used in many IT spheres.
C, in fact, is the only option for projects on Arduino and similar platforms. It can also be used on other platforms. This language is very popular for firmware development as a low-level programming language.
Kotlin is a modern and rapidly evolving language, especially among Java developers.
Building an IoT Back-End
The back-end application is developed independently of the fact that this is an IoT project. The server load, data volumes, etc. are more important here. In this case, the choice will be almost the same, but on condition that the team has experience in such complex projects — we mean the complexity of the business logic of the future server and not the fact that this is an IoT project. Let’s approximately name the top 5 languages for these purposes:
PHP — new versions of the language are free from problems of the previous ones. Most websites are developed using this programming language. The main frameworks at the moment are Symfony and Laravel.
Python — the simple syntax of the language has made it very popular among developers of different IT spheres. Python has many frameworks and libraries for various tasks.
Ruby is considered as one of the most reliable programming languages. It has an active community and is well documented. For most tasks, Ruby on Rails framework is used.
Java has a good reputation as a multi-purpose language. The main back-end framework is Spring, but many development teams are switching to Kotlin/Spring due to easier writing and reading of code.
C# is a popular language in many areas of IT, based on C++, but simpler and more convenient. Together with the .Net platform, it was developed by Microsoft and has good technical support.
Client Applications
Client applications for IoT devices are developed like any other client application on client-server systems. The choice of programming languages and other technologies will be based on client platforms for which these apps will be developed. Such platforms can be:
iOS, iPadOS and Android mobile operating systems;
Front-end web for Internet browsers and other devices based on web technologies;
Desktop operating systems: macOS, Windows, Linux;
Game consoles;
Other highly specialized platforms.
If you already know on which devices your custom app should run to control and monitor the developed IoT system, this will be the starting point for choosing a programming language and other technologies for client application development.