FastAPI Async & High-Performance Pack

Pydantic validation, dependency injection, async def vs def threadpool offloading, Starlette async middleware, and OpenAPI contracts.

FastAPI has rapidly become the standard for high-performance Python backend services and AI inference APIs. This pack covers all 15 FastAPI interview questions, teaching you when to use def vs async def, how FastAPI utilizes AnyIO threadpools for blocking operations, how dependency injection simplifies auth, and how to build scalable async endpoints.

Target AudiencePython engineers building high-performance, asynchronous web APIs and microservices with FastAPI.

Targeted Companies

MicrosoftUberNetflixCiscoScale AI

2 WeeksPlan Duration

2Curriculum Modules

15Curated Questions

4Milestones

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Structured Syllabus

Curriculum Modules (Preview Mode)

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Pydantic Schemas, Type Hints & Endpoint Mechanics

Free Preview

Request validation, response models, and def vs async def execution.

~6h

Target Competency & Objective:Understand how FastAPI uses Python type hints for validation, documentation, and serialization, and how the runtime executes async vs sync endpoints.

Core Technical Concepts Tested

Pydantic BaseModel: Field validation, request body parsing, and schema generationresponse_model filtering to prevent leaking private attributes (password_hash)async def (runs directly on main asyncio event loop) vs def (offloaded to threadpool)Why blocking I/O in async def halts the entire server process

What Fails in Production (Triage Scenarios):

Calling blocking time.sleep() or sync DB driver in async def freezing all concurrent users
Forgetting response_model leading to sensitive internal fields returned to public clients
Type coercion bugs from misconfigured Pydantic validation rules

Deep-Dive Architectural Guide

FastAPI: Sync vs Async Endpoints Explained

13 min read

Module Milestones (0 / 2)

Dependency Injection, Middleware & Async Performance

Depends() system, database sessions, BackgroundTasks, and centralized error handling.

~6h

Module 02 Content is Locked

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Module Outline

01. Pydantic Schemas, Type Hints & Endpoint MechanicsPreview 02. Dependency Injection, Middleware & Async PerformanceLocked

Specific Pack Deliverables

Mastery of async def vs standard def execution mechanics and thread pool offloading
Building reusable business logic and authentication using FastAPI's Depends() system
Strict request validation and response filtering using Pydantic BaseModel
Centralized exception handlers, custom middleware, and asynchronous background tasks

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