Compress

Response compression middleware for Fiber

Compression middleware for Fiber that automatically compresses responses with gzip, deflate, brotli, or zstd based on the client’s Accept-Encoding header.

Bodies smaller than 200 bytes remain uncompressed because compression would likely increase their size and waste CPU cycles. See the fasthttp source.

Behavior

• Skips compression for responses that already define Content-Encoding, for range requests, 206 responses, status codes without bodies, or when either side sends Cache-Control: no-transform
• HEAD requests negotiate compression so Content-Encoding, Content-Length, ETag, and Vary reflect the encoded representation, but the body is removed before sending
• When compression runs, strong ETag values are recomputed from the compressed bytes; when skipped, Accept-Encoding is still merged into Vary unless the header is * or already present

Signatures

func New(config ...Config) fiber.Handler

Usage

import (
    "github.com/gofiber/fiber/v3"
    "github.com/gofiber/fiber/v3/middleware/compress"
)

Basic Example

// Initialize default config
app.Use(compress.New())

// Or extend your config for customization
app.Use(compress.New(compress.Config{
    Level: compress.LevelBestSpeed, // 1
}))

Skip Specific Routes

app.Use(compress.New(compress.Config{
    Next:  func(c fiber.Ctx) bool {
      return c.Path() == "/dont_compress"
    },
    Level: compress.LevelBestSpeed,
}))

Configuration

Next · func(fiber.Ctx) bool · default: "nil"

Skips this middleware when the function returns true.

Level · Level · default: "LevelDefault (0)"

Compression level to use. Available levels:

• LevelDisabled (-1): Compression is disabled
• LevelDefault (0): Default compression level
• LevelBestSpeed (1): Best compression speed
• LevelBestCompression (2): Best compression

Default Config

var ConfigDefault = Config{
    Next:  nil,
    Level: LevelDefault,
}

Constants

// Compression levels
const (
    LevelDisabled        = -1
    LevelDefault         = 0
    LevelBestSpeed       = 1
    LevelBestCompression = 2
)

Common Use Cases

Maximum Compression for Static Assets

app.Use("/static", compress.New(compress.Config{
    Level: compress.LevelBestCompression,
}))

Fast Compression for API Responses

app.Use("/api", compress.New(compress.Config{
    Level: compress.LevelBestSpeed,
}))

Conditional Compression

app.Use(compress.New(compress.Config{
    Next: func(c fiber.Ctx) bool {
        // Don't compress images
        return strings.HasPrefix(c.Get("Content-Type"), "image/")
    },
}))

Selective Compression by Route

// Compress API responses
api := app.Group("/api")
api.Use(compress.New(compress.Config{
    Level: compress.LevelBestSpeed,
}))

// Don't compress file uploads
app.Post("/upload", uploadHandler) // No compression