@derodero24/comprs-middleware

HTTP compression middleware powered by comprs. Supports Express, Fastify, and Hono with zstd, brotli, gzip, and deflate.

Features

• Multi-framework — Express, Fastify, and Hono via subpath imports
• zstd, brotli, gzip, deflate — all algorithms via a single package
• Accept-Encoding negotiation — automatically selects the best encoding
• Configurable priority — control which algorithm is preferred
• Threshold support — skip compression for small responses
• Content-Type filtering — only compresses known compressible types; skips responses without a Content-Type header
• Rust-powered — uses comprs native bindings for maximum throughput

Installation

npm install @derodero24/comprs @derodero24/comprs-middleware

Usage

Express

import express from 'express';
import { comprs } from '@derodero24/comprs-middleware/express';

const app = express();
app.use(comprs());

Fastify

import Fastify from 'fastify';
import { comprs } from '@derodero24/comprs-middleware/fastify';

const app = Fastify();
app.register(comprs);

Hono

import { Hono } from 'hono';
import { comprs } from '@derodero24/comprs-middleware/hono';

const app = new Hono();
app.use(comprs());

Options

All adapters accept the same core options:

comprs({
  encodings: ['zstd', 'br', 'gzip'],   // Algorithm priority
  threshold: 512,                        // Min response size (bytes)
  level: { zstd: 3, br: 6, gzip: 6 },  // Per-algorithm levels
  filter: (req, res) => true,            // Custom filter (Express/Fastify)
})

API

Subpath exports

| Import path | Framework | Returns | |-------------|-----------|---------| | @derodero24/comprs-middleware/express | Express/Connect | (req, res, next) => void | | @derodero24/comprs-middleware/fastify | Fastify | FastifyPluginAsync | | @derodero24/comprs-middleware/hono | Hono | MiddlewareHandler | | @derodero24/comprs-middleware | — | negotiate(), types |

Option reference

| Option | Type | Default | Description | |--------|------|---------|-------------| | encodings | Encoding[] | ['zstd', 'br', 'gzip', 'deflate'] | Algorithm priority order | | threshold | number | 1024 | Minimum response size (bytes) to compress | | level | LevelOptions | {} | Per-algorithm compression levels | | filter | (req, res) => boolean | Compressible types | Custom filter (Express/Fastify) |

Hono adapter accepts filter: (c: Context) => boolean instead.

negotiate(acceptEncoding, preferred?)

Low-level Accept-Encoding negotiation. Returns the best encoding or null.

import { negotiate } from '@derodero24/comprs-middleware';

negotiate('gzip, br;q=0.8, zstd');
// => 'zstd' (highest server preference accepted by client)

Behavior

All adapters automatically:

• Set Content-Encoding header
• Remove Content-Length (compressed size is unknown)
• Set Vary: Accept-Encoding for caching correctness
• Skip compression when:
  • Response already has Content-Encoding
  • Cache-Control: no-transform is set
  • Content-Type is not compressible (images, etc.)
  • Content-Type is not set
  • Response body is below threshold
  • Request method is HEAD
  • Client does not accept any supported encoding

License

MIT