How to Hire Python Developers and Identify True Masters

Python has cemented its position as one of the most popular and influential programming languages in the world. It‘s highly sought-after across industries, from web development to data science to artificial intelligence.

As the inventor of Python Guido van Rossum put it: "Python is a widely used high-level, general-purpose, interpreted, dynamic programming language. Its design philosophy emphasizes code readability, and its syntax allows programmers to express concepts in fewer lines of code than possible in languages such as C++ or Java."

For companies looking to leverage this powerful language, finding and hiring skilled Python developers is crucial. But with so many candidates claiming Python expertise, how can you identify the true masters? As a full-stack developer and engineering manager who has interviewed hundreds of Python developers, I‘ll share my insights on effectively evaluating Python skills and finding the best fit for your team.

The Explosive Growth of Python

First, let‘s look at some data that demonstrates the incredible rise of Python and the increasing demand for Python skills:

• Python is the 3rd most popular language behind JavaScript and HTML/CSS, used by 48% of professional developers according to the 2021 Stack Overflow Developer Survey.
• Python added the most new contributors on GitHub in 2020 and 2021, more than any other language, based on the Octoverse reports.
• The PYPL PopularitY of Programming Language index, which analyzes Google searches for language tutorials, ranks Python #1 with 29% share as of November 2021.
• The TIOBE Index, which measures language popularity based on web search results, named Python the Programming Language of the Year for 2020 due to gaining the most ranking points.
• Python is in the top 3 most in-demand tech skills in 2021 based on Hired‘s State of Software Engineers Report.
• The average Python developer salary in the US is $110,840, with higher salaries for specialized roles like data scientist ($124,333) and machine learning engineer ($122,287) according to Glassdoor data.

These stats paint a clear picture: Python is immensely popular and only continuing to grow. The battle for the best Python developers is fierce and hiring managers need a keen eye for talent to stay competitive.

Key Python Skills to Look For

So what skills and qualifications should you prioritize when evaluating Python developers? The specifics will vary based on the role and domain, but here are some of the most important areas:

Core Python Programming

At a minimum, a strong Python developer should be highly proficient in core Python concepts such as:

• Data types (strings, lists, tuples, sets, dictionaries)
• Control flow (if/else, for/while loops)
• Functions and methods
• Object-oriented programming (classes, inheritance, composition)
• Exception handling
• File I/O
• Virtual environments and package/dependency management

Look for developers who can not only write Python code, but understand the pros and cons of different approaches. They should be able to discuss tradeoffs in terms of performance, readability, and maintainability.

Web Development

For Python web development roles, key skills and tools to look for include:

• Web frameworks like Django, Flask, or FastAPI
• Familiarity with front-end technologies like HTML, CSS, JavaScript
• Knowledge of web servers like Apache, Nginx, or Gunicorn
• Experience with databases like PostgreSQL, MySQL, or MongoDB and ORMs like SQLAlchemy
• RESTful API design and consumption
• Authentication and security best practices
• Async programming with tools like Celery or Dramework

A strong web developer should be able to architect and build complex, secure web applications that can scale to high volumes of traffic. They should have a deep understanding of the request-response cycle, HTTP methods, and how web servers work.

Data Science and Machine Learning

For data-heavy Python roles, prioritize these skills:

• Strong grasp of statistics and probability
• Experience with scientific computing libraries like NumPy, SciPy, and Pandas
• Data visualization tools like Matplotlib, Seaborn, or Plotly
• Machine learning frameworks like scikit-learn, TensorFlow, or PyTorch
• Familiarity with Jupyter notebooks and reproducible research
• Experience with big data tools like Apache Spark or Dask
• Cloud computing platforms like AWS, GCP, or Azure

A great Python data scientist or ML engineer can wrangle messy datasets, build and test models, and communicate results to both technical and non-technical stakeholders. They should have a strong foundation in math and statistics along with practical experience applying machine learning to real-world problems.

Certifications: Are They Valuable?

Some Python developers pursue certifications to demonstrate their knowledge. But are they actually useful for hiring?

In general, I don‘t place too much weight on certifications compared to hands-on experience and skills. Many of the best Python developers I‘ve worked with don‘t have any formal certifications.

That said, some reputable Python certifications include:

• Certified Entry-Level Python Programmer (PCEP)
• Certified Associate in Python Programming (PCAP)
• Certified Professional in Python Programming (PCPP)
• CISCO Certified Network Associate (CCNA) with Python focus

If a candidate has a certification, it‘s a positive signal that they‘ve put in effort to learn Python fundamentals and follow an established curriculum. Just don‘t mistake it as a replacement for real-world experience and problem-solving abilities.

Evaluating Python Skills

The most effective way to assess a Python developer‘s skills is to give them a hands-on coding challenge. Ideally this should be drawn from a real project that your team has encountered.

In a take-home coding challenge, key things to look for include:

• Clean, readable, well-organized code
• Appropriate choice of data structures and algorithms
• Adherence to PEP 8 style guide and docstrings
• Error handling and edge case considerations
• Unit tests to verify correctness
• README with setup, usage, and thought process documentation

A strong submission will not only solve the problem correctly but do so in a clear, maintainable way, with proper separation of concerns and robust test coverage. Ample code comments and documentation are also a positive sign.

For more senior roles, a system design or architecture challenge can also be valuable. Have the candidate outline how they would build a complex application or service, such as a real-time chat app or a recommendation engine. Look for an understanding of things like:

• Service-oriented architecture and microservices
• Database schema design and data pipelines
• Caching, rate limiting, and performance optimization
• Scalability and high availability considerations
• Security and compliance requirements
• DevOps and deployment best practices

In a live coding interview, ask the candidate to walk through their thought process and explain the choices they make. Do they break the problem down logically? Consider edge cases and performance tradeoffs? Communicate clearly and respond well to feedback?

Remember, the goal is not just to see if they can write code, but to understand how they approach problems and work through challenges. The best Python developers are not just skilled coders, but strong problem solvers and communicators.

Cultural Fit and Collaboration

Technical skills are critical, but they‘re not the whole picture. A developer‘s ability to work well with others, communicate clearly, and align with your team‘s values and ways of working is just as important.

Some key things to look for:

• Strong verbal and written communication skills
• Openness to feedback and willingness to learn
• Collaborative spirit and teamwork ethos
• Passion for their craft and eagerness to learn new things
• Alignment with your team‘s mission, values, and culture

Ask candidates about past experiences working on teams and navigating conflict. How do they prefer to give and receive feedback? What kind of work environment allows them to thrive?

Have them explain a complex technical concept as if to a non-technical stakeholder. Do they break it down clearly and patiently? Tailor the level of detail to the audience?

The best Python developers are humble, curious, and always looking to improve their skills. They contribute to the community through open source, mentoring, or knowledge sharing. They care about writing code that is not only functional, but also maintainable and elegant.

Junior vs. Senior Python Developers

When hiring Python developers, you‘ll need to decide between junior and senior-level candidates. There are pros and cons to each.

Junior Python developers may have less experience, but they can bring energy, fresh perspectives, and eagerness to learn. They often command lower salaries, making them a budget-friendly option. However, they may require more mentoring and ramp-up time to become fully productive.

Senior Python developers bring deep expertise and battle-tested experience. They can hit the ground running on complex projects, mentor junior team members, and make high-level architectural decisions. However, they also command higher salaries and may be harder to find and attract.

In general, I recommend a mix of junior and senior developers on a team. Senior developers can provide leadership and strategic direction, while junior developers bring new ideas and help with day-to-day execution. Look for senior candidates with strong mentorship and communication skills, and junior candidates with passion, potential, and diverse backgrounds.

Conclusion

Hiring Python developers is both an art and a science. There‘s no one-size-fits-all formula, but by focusing on the key skills, evaluating real-world problem-solving abilities, and assessing cultural fit, you can identify the true masters who will take your team to the next level.

Remember, the best Python developers are not just skilled coders, but also curious learners, strong communicators, and collaborative team players. They‘re passionate about their craft and always looking for ways to improve themselves and their team.

As Guido van Rossum said: "The joy of coding Python should be in seeing short, concise, readable classes that express a lot of action in a small amount of clear code — not in reams of trivial code that bores the reader to death."

Hire Python developers who embody that spirit of clean, elegant, and expressive code. Your team and your codebase will thank you.