"Python developer" means three different jobs. Here's how to hire the right one.
TL;DR — Quick Facts
Metric Data Developer adoption 57.9% (Stack Overflow 2025 ) #1 desired language To learn ML engineer premium 20-40% over backend Senior backend (US) $140k - $190k Senior ML engineer (US) $200k - $280k
Three Types of Python Developers
Type Key Skills Use For Backend Django, FastAPI, PostgreSQL APIs, web apps, microservices Data Science Pandas, NumPy, Scikit-learn Analytics, statistical modeling ML Engineer PyTorch, LangChain, MLOps AI products, LLMs, production ML
Clarify which you need before sourcing. The skills barely overlap.
Skills by Role
Backend
Must-Have Nice-to-Have Django or FastAPI Flask, GraphQL PostgreSQL, SQL Redis, MongoDB pytest, Docker Kubernetes, async
Data Science
Must-Have Nice-to-Have Pandas, NumPy Polars, Dask Scikit-learn XGBoost Matplotlib, SQL Streamlit
ML Engineering
Must-Have Nice-to-Have PyTorch or TensorFlow JAX Model serving basics TensorRT, ONNX LLM APIs Fine-tuning, RAG
Where to Find Them
Free
Source Best For available.dev Immediate hires Python Discord (350k+)Community sourcing Hugging Face contributors ML expertise Kaggle winners Data science
Paid
Source Cost LinkedIn $10-15k/year Wellfound $400/month
Evaluation by Role
Backend — Code Review (30 min)
Show this code:
def get_users(db, filters):
query = "SELECT * FROM users WHERE 1=1"
for key, value in filters.items():
query += f" AND {key} = '{value}'"
return db.execute(query)They must identify: SQL injection, missing parameterized queries, no type hints, no error handling.
Data Science — Analysis Exercise (1 hr)
Give a dataset: "What questions would you investigate? Walk me through your approach."
Look for: Statistical thinking, methodology, communication of findings.
ML Engineering — Deployment Question
"You have a PyTorch model serving 1000 req/sec. Walk me through deployment."
Look for: Quantization, ONNX, TorchServe, monitoring.
Salary Benchmarks (2026)
United States — By Specialization
Role Junior Mid Senior Staff Backend $70-95k $95-140k $140-190k $190-260k Data Scientist $80-110k $110-160k $160-220k $220-300k ML Engineer $100-140k $140-200k $200-280k $280-400k
Remote (Senior)
Region Backend ML Engineer Western Europe $100-150k $130-200k Eastern Europe $55-95k $75-130k Latin America $50-85k $65-110k
Sources: Levels.fyi , AI Jobs
Common Mistakes
1. Data scientist vs data analyst — Scientists build models; analysts create dashboards. Most companies need analysts.2. ML engineers too early — Until you have millions of data points and clear use cases, use OpenAI APIs.3. Wrong evaluation — Testing Django for a data science role (or vice versa) wastes everyone's time.4. Notebooks ≠ production code — Verify data scientists can write tested, deployable Python.
FAQ
Django vs FastAPI?
Django: Full web apps, admin interface needed, batteries-included.
FastAPI: Pure APIs, high performance, async-first.
Python vs Go/Rust for backend?
Python wins for: Fast development, ML integration, MVPs. Go/Rust wins for: High performance, high concurrency.
Is notebook experience enough?
No. Notebooks don't teach version control, testing, error handling, or deployment. Verify production skills separately.
Bottom Line
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