fastapi

fastapi is a cursor rule for Cursor from PatrickJS/awesome-cursorrules. It costs 427 tokens per session, scanned A, original, CC0-1.0.

A set of Python guidelines for building FastAPI web APIs, including project structure, validation, databases, authentication, and security.

In plain words
What is it for?
Use it when creating or reviewing FastAPI services, request and response models, database code, authentication, documentation, and middleware.
Why use it?
It provides consistent patterns for designing API endpoints and handling data, errors, users, and common security concerns.

Cursor rule for Cursor

Written for Cursor: a Cursor rule (.mdc).

Good fit Use it when creating or reviewing FastAPI services, request and response models, database code, authentication, documentation, and middleware.

Compare 6 cursor rules from other repositories ↓
Install with agentmods
npx agentmods add rules/patrickjs/awesome-cursorrules/fastapi
About the project

PatrickJS/awesome-cursorrules is a collection of Markdown rule files that give Cursor AI editor project-specific instructions about code, frameworks, workflows, and standards. Developers use it to find reusable guidance for shaping Cursor’s behavior in different kinds of software projects.

PatrickJS/awesome-cursorrules · 40,914 stars · on GitHub

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.

Clone the repo
git clone --depth 1 https://github.com/PatrickJS/awesome-cursorrules

Made for: Cursor.

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.

agentmods badge for fastapi

README.md
[![agentmods](https://agentmods.dev/badge/rules/patrickjs/awesome-cursorrules/fastapi/github.svg)](https://agentmods.dev/rules/patrickjs/awesome-cursorrules/fastapi)
Your own site
<a href="https://agentmods.dev/rules/patrickjs/awesome-cursorrules/fastapi"><img src="https://agentmods.dev/badge/rules/patrickjs/awesome-cursorrules/fastapi/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.

agentmods 80×15 button for fastapi

Your own site · 80×15
<a href="https://agentmods.dev/rules/patrickjs/awesome-cursorrules/fastapi"><img src="https://agentmods.dev/badge/rules/patrickjs/awesome-cursorrules/fastapi.svg" alt="Reviewed on agentmods" width="80" height="20"></a>
Per session 427 This file is loaded in full into every session.
When invoked 427 The same file — it is already loaded in full.
Security scan A 0 findings. A grade says what 26 rules found in the file — not that it is safe.
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.

ModelPer sessionOnce invoked
Fable 5.1 $0.00427 $0.00427
Opus 5.5 $0.00171 $0.00171
Sonnet 5.5 $0.00085 $0.00085
Haiku 4.5 $0.00043 $0.00043

Measured 1mo ago against content hash 0c94b5295310, method: parsed. Prices are Anthropic first-party input rates as of 2026-10-07, from the pricing page.

Security

Grade A, and why

fastapi 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 1mo ago.

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.

Origin

Copies of this mod

6 near-identical copies found in the catalogue:

  • fastapi — 97% identical, 7 lines differ
  • fastapi — 97% identical, 7 lines differ
  • fastapi — 97% identical, 6 lines differ
  • fastapi — 97% identical, 7 lines differ
  • fastapi — 97% identical, 7 lines differ
  • fastapi — 95% identical, 1 lines differ
rules/fastapi.mdc · 87 lines

What it actually says

FastAPI Best Practices

Project Structure

  • Use proper directory structure
  • Implement proper module organization
  • Use proper dependency injection
  • Keep routes organized by domain
  • Implement proper middleware
  • Use proper configuration management

API Design

  • Use proper HTTP methods
  • Implement proper status codes
  • Use proper request/response models
  • Implement proper validation
  • Use proper error handling
  • Document APIs with OpenAPI

Models

  • Use Pydantic models
  • Implement proper validation
  • Use proper type hints
  • Keep models organized
  • Use proper inheritance
  • Implement proper serialization

Database

  • Use proper ORM (SQLAlchemy)
  • Implement proper migrations
  • Use proper connection pooling
  • Implement proper transactions
  • Use proper query optimization
  • Handle database errors properly

Authentication

  • Implement proper JWT authentication
  • Use proper password hashing
  • Implement proper role-based access
  • Use proper session management
  • Implement proper OAuth2
  • Handle authentication errors properly

Security

  • Implement proper CORS
  • Use proper rate limiting
  • Implement proper input validation
  • Use proper security headers
  • Handle security errors properly
  • Implement proper logging

Performance

  • Use proper caching
  • Implement proper async operations
  • Use proper background tasks
  • Implement proper connection pooling
  • Use proper query optimization
  • Monitor performance metrics

Testing

  • Write proper unit tests
  • Implement proper integration tests
  • Use proper test fixtures
  • Implement proper mocking
  • Test error scenarios
  • Use proper test coverage

Deployment

  • Use proper Docker configuration
  • Implement proper CI/CD
  • Use proper environment variables
  • Implement proper logging
  • Use proper monitoring
  • Handle deployment errors properly

Documentation

  • Use proper docstrings
  • Implement proper API documentation
  • Use proper type hints
  • Keep documentation updated
  • Document error scenarios
  • Use proper versioning
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.

  1. 1mo ago First seen · 87 lines · 0 tokens per session scan A 0c94b5295310

Subscribe to this mod's changes

fastapi is a cursor rule published in the GitHub repository PatrickJS/awesome-cursorrules (40,914 stars, last pushed 4mo ago), licensed CC0-1.0. It adds 427 tokens to every session, about $0.0017 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 2026-08-30.