What is fastapi-development?

A guide to building Python web APIs with FastAPI, a framework for creating HTTP services. It covers asynchronous routes, input validation, authentication, dependency injection, database integration, and automatic API documentation.

Use it to build REST endpoints, microservices, validated request handling, JWT authentication, and OpenAPI or Swagger documentation.

It helps structure modern Python APIs while checking incoming data and generating documentation. It also supports services that need asynchronous request handling.

fastapi-development — Skill for Claude Code and Codex by aj-geddes

Install

Getting it into your agent

One page per mod, every tool's command on it. A separate URL per tool would split the same page into five that compete with each other.

Any agent

npx skills add aj-geddes/useful-ai-prompts --skill fastapi-development

Clone the repo

git clone --depth 1 https://github.com/aj-geddes/useful-ai-prompts

Made for: Claude Code, Codex.

Wrote this? Show the measurements

A badge with what this costs and how it scanned, read live from this page, so it follows the numbers instead of freezing them. Markdown for a README, HTML for a documentation site or a project page.

README.md

[![agentmods](https://agentmods.dev/badge/skills/aj-geddes/useful-ai-prompts/fastapi-development/github.svg)](https://agentmods.dev/skills/aj-geddes/useful-ai-prompts/fastapi-development)

Your own site

<a href="https://agentmods.dev/skills/aj-geddes/useful-ai-prompts/fastapi-development"><img src="https://agentmods.dev/badge/skills/aj-geddes/useful-ai-prompts/fastapi-development/github.svg" alt="Measured on agentmods" height="20"></a>

Or the 80×15 button, for a site that already has a row of RSS and ATOM ones. Only the verdict fits; the numbers stay here.

Your own site · 80×15

<a href="https://agentmods.dev/skills/aj-geddes/useful-ai-prompts/fastapi-development"><img src="https://agentmods.dev/badge/skills/aj-geddes/useful-ai-prompts/fastapi-development.svg" alt="Reviewed on agentmods" width="80" height="20"></a>

Per session 46 Skills are progressive disclosure: only the name and description are preloaded; the body loads when the skill is used.

When invoked 716 The whole file, excluding the scripts and references it only reads on demand.

Security scan A 0 findings. A grade says what 26 rules found in the file — not that it is safe. Third-party audits

Socket warn 16 Sept 2026
Snyk pass 16 Sept 2026

How audits are shown

Origin original No closer match found in the catalogue.

Token cost

What it costs to keep this loaded

Counted locally with the o200k_base tokenizer, which is exact for GPT models; Claude uses its own tokenizer and its counts differ. Treat this as one consistent yardstick across the catalogue rather than a bill. Prices are per million input tokens.

Model	Per session	Once invoked
Fable 5.1	$0.00046	$0.00716
Opus 5.5	$0.00018	$0.00286
Sonnet 5.5	$0.00009	$0.00143
Haiku 4.5	$0.00005	$0.00072

Measured 2mo ago against content hash 457d44d0eda3, method: parsed. Prices are Anthropic first-party input rates as of 2026-10-07, from the pricing page.

Security

Grade A, and why

fastapi-development scanned grade A with 0 findings against 26 rules in 11 categories — prompt injection, anti-refusal, data exfiltration, privilege escalation, supply chain, agent snooping, system-prompt leakage, SSRF and excessive agency — measured 2mo ago.

The scan reads SKILL.md. This mod also ships 1 executable file (scripts/validate-api.sh), listed below but not scanned — reading those needs a real analyzer, not pattern matching.

A static scan of the body, not an audit. Every finding is printed with the line that produced it so you can judge whether it matters here. A mod is markdown that instructs an agent; that is exactly why what it instructs is worth reading.

Nothing flagged

None of the 26 patterns this scan looks for appear in this file: no shell pipes, no recursive deletes, no credential paths, no hidden text, no instruction-override or anti-refusal phrasing, no agent-config snooping. That is not a guarantee, it is the absence of the things that are checkable.

skills/fastapi-development/SKILL.md · 105 lines

How it starts

The opening of the file, as written. The whole thing — 105 lines — stays where its author put it; the contents beside it link to each section on GitHub.

Overview

Create fast, modern Python APIs using FastAPI with async/await support, automatic API documentation, type validation using Pydantic, dependency injection, JWT authentication, and SQLAlchemy ORM integration.

When to Use

Building high-performance Python REST APIs
Creating async API endpoints
Implementing automatic OpenAPI/Swagger documentation
Leveraging Python type hints for validation
Building microservices with async support
Integrating Pydantic for data validation

Quick Start

Minimal working example:

# main.py
from fastapi import FastAPI, HTTPException, status
from fastapi.middleware.cors import CORSMiddleware
from contextlib import asynccontextmanager
import logging

# Setup logging
logging.basicConfig(level=logging.INFO)
logger = logging.getLogger(__name__)

# Create FastAPI instance
app = FastAPI(
    title="API Service",
    description="A modern FastAPI application",
    version="1.0.0",
    docs_url="/api/docs",
    openapi_url="/api/openapi.json"
)

# Add CORS middleware
app.add_middleware(
    CORSMiddleware,
    allow_origins=["http://localhost:3000"],
    allow_credentials=True,
    allow_methods=["*"],
// ... (see reference guides for full implementation)

Reference Guides

Detailed implementations in the references/ directory:

Guide	Contents
FastAPI Application Setup	FastAPI Application Setup
Pydantic Models for Validation	Pydantic Models for Validation
Async Database Models and Queries	Async Database Models and Queries
Security and JWT Authentication	Security and JWT Authentication
Service Layer for Business Logic	Service Layer for Business Logic
API Routes with Async Endpoints	API Routes with Async Endpoints

Read the full file on GitHub · 105 lines

Files

What ships with it

8 files beside SKILL.md in the same directory: the scripts, references and assets a skill reads on demand. Not counted in the per-session cost; read them before you install if any of them is executable.

Changes

What this file has done since we first saw it

Hashed on every crawl. A supply-chain change to an agent config is a question of when, not whether, so the history is kept rather than the latest state alone.

2mo ago First seen · 105 lines · 46 tokens per session scan A 457d44d0eda3

Subscribe to this mod's changes

fastapi-development is a skill published in the GitHub repository aj-geddes/useful-ai-prompts (376 stars, last pushed 8mo ago), licensed MIT. It adds 46 tokens to every session and 716 once invoked, about $0.0002 per session on Opus 5.5. A static security scan graded it A with 0 findings. No closer match exists in the catalogue, so it is treated as the original; first seen 2026-09-03.

Backend and APIs Languages Python

fastapi-development next to 6 skills from other repositories
Mod	Type	Stars	Last push	Licence	Scan	Tokens	Works with
fastapi-developmentaj-geddes/useful-ai-prompts	Skill	376	8mo ago	MIT	A	46	Claude Code, Codex
fastapi-patternsaffaan-m/ECC	Skill	298k	4d ago	MIT	A	35	Claude Code, Kiro
stripe-projectse2b-dev/E2B	Skill	15k	yesterday	Apache-2.0	A	51	Claude Code, Codex
azure-mgmt-botservice-pymicrosoft/skills	Skill	3.2k	yesterday	MIT	A	59	Claude Code
azure-messaging-webpubsubservice-pymicrosoft/skills	Skill	3.2k	yesterday	MIT	A	64	Claude Code
azure-messaging-webpubsubservice-pybenjaminasterA/antigravity-awesome-skills	Skill	461	yesterday	MIT	A	0	Claude Code, Codex
azure-appconfiguration-pybenjaminasterA/antigravity-awesome-skills	Skill	461	yesterday	MIT	A	0	Claude Code, Codex

fastapi-development