flask-orjson

What it is and what it does

flask-orjson is a Flask extension that swaps out Flask's built-in JSON encoder for orjson, a third-party library optimized for fast JSON serialization. You install it, import OrjsonProvider, and assign it to your Flask app's json property in a single line. The package is thin—it exists only to bridge Flask's JSON interface with orjson's performance characteristics.

The main use case is reducing latency in Flask applications that handle significant JSON traffic. Since JSON encoding and decoding can be a bottleneck in web services, using a faster serializer can improve throughput and response times. The package is marked Production/Stable and carries no known vulnerabilities, but maintenance is dormant, so it may not track changes in Flask or orjson closely.

Use it for:

• Speed up JSON response generation in Flask APIs that handle high request volume or large JSON payloads.
• Reduce latency when parsing incoming JSON request bodies in REST endpoints.
• Replace Flask's default JSON encoder in existing applications without rewriting serialization logic.
• Improve throughput in microservices where JSON is the primary data format.

Worth the install?

AI-flagged interpretation of the facts on this page — verify before relying

Replaces Flask's default JSON encoder with orjson, a faster JSON serialization library, to speed up JSON request parsing and response generation in Flask applications.

Yes, if you are running a Flask application and JSON performance is a measurable concern. The package is simple, low-friction to install, carries no vulnerabilities, and uses a permissive license. However, dormant maintenance means you should verify compatibility with your Flask and orjson versions before deploying to production, and be prepared to maintain a fork if Flask's JSON interface changes significantly.

Install

flask-orjson on PyPI

pip install flask-orjson

uv add flask-orjson

poetry add flask-orjson

Installing flask-orjson

Before you install

Low install friction with only two runtime dependencies (flask and orjson). Maintenance is dormant—last release was over a year ago—but the package is marked Production/Stable.

License in practice

Licensed under MIT (permissive), so you can use, modify, and distribute this package freely in both open-source and commercial projects with minimal legal friction.

Quickstart

pip install flask-orjson

from flask import Flask
from flask_orjson import OrjsonProvider

app = Flask(__name__)
app.json = OrjsonProvider(app)

Requires Python 3.8 or later and an existing Flask application to integrate with.

Verify before relying

• Actual performance improvement magnitude compared to Flask's default JSON encoder in typical workloads.
• Compatibility with recent Flask versions given dormant maintenance status.
• Whether orjson's serialization behavior is a drop-in replacement for all JSON types Flask applications typically use.

Package facts

Evidence: flask_orjson-2.0.0-py3-none-any.whl

Tags

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