brotli-asgi

BrotliMiddleware adds Brotli response compression to ASGI applications (Starlette, FastAPI, Quart, etc.). It provides faster and more dense compression than GZip, and can be used as a drop in replacement for the GZipMiddleware shipped with Starlette.

Installation

pip install brotli-asgi

Examples

Starlette

from starlette.applications import Starlette
from starlette.responses import JSONResponse
from starlette.routing import Route
from starlette.middleware import Middleware

from brotli_asgi import BrotliMiddleware

async def homepage(request):
    return JSONResponse({"data": "a" * 4000})

app = Starlette(
  routes=[Route("/", homepage)],
  middleware=[Middleware(BrotliMiddleware)],
)

FastAPI

from fastapi import FastAPI
from brotli_asgi import BrotliMiddleware

app = FastAPI()
app.add_middleware(BrotliMiddleware)

@app.get("/")
def home() -> dict:
    return {"data": "a" * 4000}

API Reference

Overview

app.add_middleware(
  BrotliMiddleware,
  quality=4,
  mode="text",
  lgwin=22,
  lgblock=0,
  minimum_size=400,
  gzip_fallback=True
)

Parameters:

• (Optional) quality: Controls the compression speed vs compression density tradeoff. The higher the quality, the slower the compression. Range is 0 to 11.
• (Optional) mode: The compression mode can be: "generic" (default), "text" (for UTF-8 format text input) or "font" (for WOFF 2.0).
• (Optional) lgwin: Base 2 logarithm of the sliding window size. Range is 10 to 24.
• (Optional) lgblock: Base 2 logarithm of the maximum input block size. Range is 16 to 24. If set to 0, the value will be set based on the quality.
• (Optional) minimum_size: Only compress responses that are bigger than this value in bytes.
• (Optional) gzip_fallback: If True, uses gzip encoding if br is not in the Accept-Encoding header.

Performance

To better understand the benefits of Brotli over GZip, please read the great article written by Akamai team, Understanding Brotli's Potential, where detailed information and benchmarks are provided.

A simple comparative example using Python sys.getsizof() and timeit:

# ipython console
import gzip
import sys

import brotli
import requests

page = requests.get("https://github.com/fullonic/brotli-asgi").content
%timeit brotli.compress(page, quality=4)
# 1.83 ms ± 43 µs per loop (mean ± std. dev. of 7 runs, 1000 loops each)
sys.getsizeof(brotli.compress(page, quality=4))
# 20081
%timeit gzip.compress(page, compresslevel=6)
# 2.75 ms ± 29.8 µs per loop (mean ± std. dev. of 7 runs, 100 loops each)
sys.getsizeof(gzip.compress(page, compresslevel=6))
# 20640

Compatibility

According to caniuse.com, Brotli is supported by all major browsers with a global use of 94%.