Quickstart

December 2, 2025 · View on GitHub

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Flask-Limiter


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Flask-Limiter adds rate limiting to Flask <https://flask.palletsprojects.com>_ applications.

You can configure rate limits at different levels such as:

  • Application wide global limits per user
  • Default limits per route
  • By Blueprints <https://flask-limiter.readthedocs.io/en/latest/recipes.html#rate-limiting-all-routes-in-a-blueprint>_
  • By Class-based views <https://flask-limiter.readthedocs.io/en/latest/recipes.html#using-flask-pluggable-views>_
  • By individual routes <https://flask-limiter.readthedocs.io/en/latest/index.html#decorators-to-declare-rate-limits>_

Flask-Limiter can be configured <https://flask-limiter.readthedocs.io/en/latest/configuration.html>_ to fit your application in many ways, including:

  • Persistance to various commonly used storage backends <https://flask-limiter.readthedocs.io/en/latest/#configuring-a-storage-backend>_ (such as Redis, Memcached & MongoDB) via limits <https://limits.readthedocs.io/en/stable/storage.html>__
  • Any rate limiting strategy supported by limits <https://limits.readthedocs.io/en/stable/strategies.html>__

Follow the quickstart below to get started or read the documentation <http://flask-limiter.readthedocs.org/en/latest>_ for more details.

Quickstart

Install

.. code-block:: bash

pip install Flask-Limiter

Add the rate limiter to your flask app

.. code-block:: python

app.py

from flask import Flask from flask_limiter import Limiter from flask_limiter.util import get_remote_address

app = Flask(name) limiter = Limiter( get_remote_address, app=app, default_limits=["2 per minute", "1 per second"], storage_uri="memory://", # Redis # storage_uri="redis://localhost:6379", # Redis cluster # storage_uri="redis+cluster://localhost:7000,localhost:7001,localhost:70002", # Memcached # storage_uri="memcached://localhost:11211", # Memcached Cluster # storage_uri="memcached://localhost:11211,localhost:11212,localhost:11213", # MongoDB # storage_uri="mongodb://localhost:27017", strategy="fixed-window", # or "moving-window", or "sliding-window-counter" )

@app.route("/slow") @limiter.limit("1 per day") def slow(): return "24"

@app.route("/fast") def fast(): return "42"

@app.route("/ping") @limiter.exempt def ping(): return 'PONG'

Inspect the limits using the command line interface

.. code-block:: bash

pip install Flask-Limiter[cli]

.. code-block:: bash

$ FLASK_APP=app:app flask limiter limits

app ├── fast: /fast │ ├── 2 per 1 minute │ └── 1 per 1 second ├── ping: /ping │ └── Exempt └── slow: /slow └── 1 per 1 day

Run the app

.. code-block:: bash

$ FLASK_APP=app:app flask run

Test it out

The fast endpoint respects the default rate limit while the slow endpoint uses the decorated one. ping has no rate limit associated with it.

.. code-block:: bash

curllocalhost:5000/fast42curl localhost:5000/fast 42 curl localhost:5000/fast 42 $ curl localhost:5000/fast

429 Too Many Requests

Too Many Requests

2 per 1 minute

$ curl localhost:5000/slow 24 $ curl localhost:5000/slow 429 Too Many Requests

Too Many Requests

1 per 1 day

$ curl localhost:5000/ping PONG $ curl localhost:5000/ping PONG $ curl localhost:5000/ping PONG $ curl localhost:5000/ping PONG