Swagger UI

Interactive API documentation and testing.

Quick Start

Run your application with web_run():

from fasthttp import FastHTTP
from fasthttp.response import Response

app = FastHTTP()


@app.get("https://httpbin.org/get")
async def get_data(resp: Response) -> dict:
    return resp.json()


app.web_run()

After running, open in browser:

• Swagger UI: http://127.0.0.1:8000/docs
• ReDoc: http://127.0.0.1:8000/redoc
• OpenAPI Schema: http://127.0.0.1:8000/openapi.json

Available Endpoints

Endpoint	Description
/docs	Swagger UI interface (dark mode toggle in the top-right corner)
/redoc	ReDoc — clean, read-only alternative view
/openapi.json	OpenAPI schema in JSON
/request	Proxy for executing requests

Using Swagger UI

Viewing Documentation

All HTTP requests are automatically displayed with:

• HTTP method (GET, POST, PUT, DELETE)
• URL address
• Description from docstring
• Request parameters
• Pydantic response models

Testing Requests

1. Find the desired endpoint in the list
2. Click to expand
3. Click "Execute" button
4. View response in Response section

Custom Host and Port

app.web_run(host="0.0.0.0", port=8080)

Custom Docs Base URL

app.web_run(base_url="/api")

Now the docs will be available at http://127.0.0.1:8000/api/docs.

Customizing API Info

Pass title, version, and description to FastHTTP to control what Swagger UI shows in the header:

from fasthttp import FastHTTP
from fasthttp.response import Response

app = FastHTTP(
    title="Payments API",
    version="3.1.0",
    description="""
## Payments API

Charge cards, issue refunds, and query transaction history.

Markdown is **supported**.
""",
)


@app.get("https://api.example.com/transactions")
async def list_transactions(resp: Response) -> list:
    """List recent transactions."""
    return resp.json()


app.web_run()

Parameter	Default	Description
title	"FastHTTP API"	API name shown in Swagger UI header
version	"1.0.0"	Version string next to the title
description	""	Markdown description below the title

Security Schemes in Swagger UI

When routes use auth=, FastHTTP automatically adds the corresponding security scheme to components/securitySchemes and attaches a lock icon to protected operations in Swagger UI.

from fasthttp import FastHTTP, BearerAuth, BasicAuth
from fasthttp.response import Response

app = FastHTTP(title="Secure API", version="1.0.0")


@app.get(
    "https://api.example.com/profile",
    auth=BearerAuth(token="my-token"),
    tags=["users"],
)
async def get_profile(resp: Response) -> dict:
    """Protected with Bearer token."""
    return resp.json()


@app.get(
    "https://legacy.example.com/data",
    auth=BasicAuth(username="admin", password="pass"),
    tags=["legacy"],
)
async def get_legacy_data(resp: Response) -> dict:
    """Protected with Basic auth."""
    return resp.json()


@app.get("https://api.example.com/status", tags=["public"])
async def status(resp: Response) -> dict:
    """Public — no lock icon."""
    return resp.json()


app.web_run()

FastHTTP emits the following scheme entries automatically:

Auth class	Scheme name	OpenAPI type
BearerAuth	bearerAuth	http / bearer / JWT
BasicAuth	basicAuth	http / basic
DigestAuth	digestAuth	http / digest
OAuth2ClientCredentials	oauth2ClientCredentials	oauth2 / clientCredentials

Schemes are only added to the schema when at least one route uses the corresponding auth= class.

With Tags

@app.get("https://api.example.com/data", tags=["users"])
async def get_data(resp: Response) -> dict:
    return resp.json()

Example

from fasthttp import FastHTTP
from fasthttp.response import Response
from pydantic import BaseModel


class User(BaseModel):
    id: int
    name: str
    email: str


app = FastHTTP()


@app.get("https://jsonplaceholder.typicode.com/users/1", response_model=User)
async def get_user(resp: Response) -> dict:
    return resp.json()


@app.post("https://jsonplaceholder.typicode.com/users")
async def create_user(resp: Response) -> dict:
    return resp.json()


# Run with Swagger UI
app.web_run()

Now open http://127.0.0.1:8000/docs or your prefixed docs URL such as http://127.0.0.1:8000/api/docs.