Use

Use mounts middleware on a prefix (or mount) path: it runs for every request whose path begins with that prefix, on any HTTP method. Prefixes require either an exact match or a slash boundary, so /john matches /john and /john/doe but not /johnnnnn. Parameter tokens like :name, :name?, *, and + are still expanded before the boundary check runs. Called without a path, Use matches every request.

Signature

func (app *App) Use(args ...any) Router

// Fiber inspects args to support these common usage patterns:
// - app.Use(handler, handlers ...any)
// - app.Use(path string, handler, handlers ...any)
// - app.Use(paths []string, handler, handlers ...any)
// - app.Use(path string, subApp *App)

Each handler argument can independently be a Fiber handler (with or without an error return), an Express-style callback, a net/http handler, or any other supported shape including fasthttp callbacks that return errors.

Examples

// Match any request
app.Use(func(c fiber.Ctx) error {
    return c.Next()
})

// Match request starting with /api
app.Use("/api", func(c fiber.Ctx) error {
    return c.Next()
})

// Match requests starting with /api or /home (multiple-prefix support)
app.Use([]string{"/api", "/home"}, func(c fiber.Ctx) error {
    return c.Next()
})

// Attach multiple handlers (they run in order; each must call c.Next() to continue)
app.Use("/api", func(c fiber.Ctx) error {
    c.Set("X-Custom-Header", "value")
    return c.Next()
}, func(c fiber.Ctx) error {
    return c.Next()
})

// Mount a sub-app
app.Use("/api", api)