Hypercorn

Last updated: Mar 24, 2026

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Rationale

Hypercorn is the web server used by Fluid Attacks' platform.

The main reasons why we chose it over other alternatives are:

• It is open source.
• It has full asynchronous programming support, which is critical for performance.
• It supports both HTTP/2 and HTTP/3; this is critical for both security and performance.
• It has full parallelism support, allowing us to have several workers within a single machine, which is critical for performance.
• It supports hot reloading, critical for the development experience.
• It seamlessly integrates with Starlette.

Alternatives

These alternatives were considered but not chosen for the following reasons:

Granian

• Granian only supports HTTP/2, which reduces security and performance.
• It is still a highly experimental project that could become relevant in the future.

Socketify.py

• Socketify only supports HTTP/2, which reduces security and performance.
• It only performs considerably faster when implemented as a framework, which would force us to also replace Starlette with it, increasing complexity.
• Its fastest variants require us to use PyPy, increasing complexity.
• It does not support hot reloading, decreasing the development experience.

Uvicorn

• Uvicorn only supports HTTP/1.1, which reduces security and performance.
• It does not support parallelism, negatively impacting performance.

Gunicorn

• Gunicorn requires implementing Uvicorn for ASGI support, thus inheriting most of the disadvantages mentioned before.
• We detected a high rate of 5XX HTTP errors when using it.

Usage

We use Hypercorn as the web server for Fluid Attacks' platform.