How to Interview a Flutter Developer and What to Look For?

The most confidence-inspiring candidates in technical interviews come with years of experience, a heavyweight portfolio, and a rich history of glowing references to back-up their skills. These candidates are more difficult to find when the technology you’re interviewing for has only recently entered the market. Look at our article on hiring Flutter developers to find out tips on how to attract top talent.

Flutter is one of these tricky technologies. First launched in late 2018, in engineering terms, it’s still a relative newcomer to app development. Developers haven’t yet had the time to build up the many years of experience and expertise we often see with more mature tools. In many respects, this can be as much of an advantage as it is a problem.

Unique to interviewing Flutter developers, the platform gives you a chance to see how candidates learn new skills and pick-up new techniques. In many cases, Flutter developers have had to evolve their skills along with the platform, with some taking an active role in providing feedback and changes to aid its continued progression. Valuable skills an engineer can bring to your company.

In interviewing a Flutter developer, you’re looking for an experienced head that has worked across multiple languages, competing frameworks, and diverging platforms. You’re looking for someone who can utilise rapidly evolving feature-sets and engineer robust applications which will last.

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Included below are the interview questions that can help you gain valuable insight into candidates’ abilities and expertise. With careful application and a keen eye, these questions can open the door to the candidates who will land their ideal role within your company.

Soft Skill Questions for Flutter Developers

Just as critical as technical know-how and engineering abilities, soft skills will tell you how well a candidate is likely to fit within a team environment. Often underestimated, questions about soft skills help inform you of a candidate’s productivity, teamwork, and potential for future learning and development.

Tell me about a situation where you had to do something you have never done before. How did you handle it? What did you learn from it?

Diving into new technologies and learning new things is key to project success. In developing with a young, modern platform such as Flutter, these skill-sets become even more critical still. Finding out how comfortable a candidate is working in an unfamiliar environment is a great way to gauge how successful new projects are likely to be.

Have you ever had to produce work within a difficult working relationship? What was the issue? How did you resolve it?

Effective teams are crucial to any development project. How well these teams come together can be directly measured in the quality and quantity of their product output. The ability to solve major problems is a major asset to bring on board.

Recall a time when you were facing a significant issue, but your manager was unavailable. How did you solve it? How would you handle it now?

Finding out how far a candidate can progress independently, even against the odds, is a signal of how well they’re likely to progress without extensive micro-management. Finding out what they’ve learned from previous experiences can be a useful tool to see how they’re progressing through their careers.

Flutter Interview Questions About General Development

Until very recently, Flutter’s typical use-case was rooted in cross-platform mobile app development. Having only been released in late 2018, the framework is likely to be a late addition to any mobile developer's skill-set. Senior developers will have experience creating apps using native tools or alternate frameworks in the past.

Asking questions about their general approach to mobile app development can give you a fuller sense of each candidate’s skills and qualities as a mobile application engineer. The questions below are intended to inform you of a candidate’s generalised skill-set before focusing on Flutter interview questions.

Tell me about some of the mobile apps you have developed

Asking a candidate to talk about their work highlights is the best insight you’ll get into how they can discuss technical topics. Choosing a topic they’d be expected to know very well and be passionate about too can set the right candidate up for success.

Here, a portfolio of previously published apps can help sell a candidate’s abilities better than anything else. Even if they’re not built using Flutter, they can tell you a great deal about a candidate’s abilities. You should have the opportunity to determine if their apps meet your expectations, whether they match the technical knowledge you’d expect, and whether you’d be happy with similar applications representing your organisation in the marketplace.

Tell me about your greatest challenge as a mobile app developer and how you overcame it

Since software development is, at heart, a profession based on the ability to solve problems—many of our questions focus on that aspect of the role. Asking about a developer’s most difficult professional challenges can tell you a lot about the depth of their experience.

Where do you see the future of Flutter development?

The answer to this question is investigated more fully in our article about the future of Flutter development.

Tell me about various technologies you’ve used to implement previous mobile apps

Experienced app developers will have used technologies and frameworks outside of Flutter. Many will have used native application tools, cross-platform frameworks, or responsive web designs.

A great follow-up question should be to ask about the relative strengths and weaknesses of technologies they’ve used against each other and against Flutter development tools. A complete answer to this follow-up should discuss implications on performance, user interface, and app functionality.

Technical Flutter Interview Questions

You’re interviewing for a Flutter application developer, so it stands to reason you should ask questions on the platform itself. Asking the right questions beforehand should give you a firm idea of the kind of developer they are, how well they could fit into the organisation, and the amount of experience they have under their belt.

These Flutter-specific interview questions should provide insights into how well they know the platform’s features and the Dart language too. Starting at the easier end of the scale and moving into more detailed topics, these questions will give you an insight into a candidate’s platform-specific experience.

What is a Widget in Flutter?

In Flutter, everything is a widget. From the app itself down through the code into UI components and views. Arranged in a tree structure, the UI of a Flutter app is constructed from nested widgets which define everything from layout to function and state.

Widgets have analogs in other frameworks too. In React, for example, similar structures are called components. A candidate may mention the similarity between the two. A senior developer may be expected to know that Flutter draws its own UI widgets while frameworks such as React Native render components into native code for the targeted platform.

What’s the difference between stateless and stateful widgets?

In Flutter, Widgets are split into two categories: stateless and stateful.

A stateless widget handles no data. They are created once and don’t store any values that may change over time. A stateful widget, in contrast, is dynamic in nature. Its values may update the UI and store values which influence the application in some way.

In the simplest possible terms: a user may manipulate a stateful widget such as an input field, text box, button, or slider.

Outline the lifecycle of a stateful Widget

The full widget lifecycle, in order, should feature:

• createState()— A method called immediately on a stateful widget. The method should return a widget’s State object
• initiate()—The first method called after the widget is created
• didChangeDependencies()—Called the first time the widget is built and immediately after initState()
• build()—Called only once in a stateless Widget. In a stateful Widget, it’s called every time the UI needs to render the widget. The method should return a widget’s tree
• didUpdateWidget()—Called when there are changes to the parent widget changes the widget is forced to redraw its own UI
• deactivate()—Called when this object is removed from the tree
• dispose()—Deallocates memory for the widget and its state

What is a Scoped Model?

Scoped model is an architecture pattern that separates business logic from UI code. The advantages are the ease with which you can pass a data model from a parent Widget to its descendants.

What are some of the most impactful differences between Flutter and a Web application?

A good answer will focus primarily on the inefficiencies of a web application. Using various frameworks and tools can overcome some of the access limitations and drawbacks of a web application, but their inefficiencies and latency will always remain as a result of the various architecture layers required.

Flutter, in contrast, compiles Dart into native ARM code which will run more efficiently by design.

When might you use a Native app rather than a Flutter one?

This may feel a bit like a trick question when interviewing for a Flutter role, but knowing when to utilise a powerful tool and when not to is a crucial skill for developers.

When an app absolutely must be lightweight due to device restraints, legacy operating systems, or for instant apps, then a Native app—which is more lightweight by design—is often a more sensible approach.

How to Assess a Strong Flutter Developer

How a developer solves tough problems is every bit as important as the solution they come up with. Pay close attention to how they tackle practical exercises and the details they provide in response to solving technical challenges.

Code samples, written exercises, and a rich portfolio can go a long way to demonstrating the abilities of any candidate. If they’re provided for you to review, use them well. A glimpse at their coding style, commenting, and documentation is a valuable insight.

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Intuition and Insight in Interviewing Flutter Developers

Finding the ideal developer in any language or platform is no easy task. The challenges of the interview are only made greater by introducing cutting-edge tools and technologies into the mix. The perfect interview should highlight the right combination of organisation, creativity, technical know-how, and engineering skill.

These questions, however, can’t determine all of that all on their own. They’re merely an introduction to each of these qualities. They are an insight into how a candidate will respond to technical challenges and practical problems. They are an introduction to the specific problems and challenges within your firm which you’re asking them to solve.​

Up next, check out what to do when you’ve assembled your remote Flutter team, The Do's & Don'ts of Managing an Outsourced Flutter Development Team.