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The App type represents your Fiber application and provides methods for routing, configuration, and server lifecycle management.

​
Creating an App

​
New

Creates a new Fiber application instance. 
func New(config ...Config) *App
​
config
Config
Optional configuration for the app. See fiber.mdx for all config options.
​
*App
*App
Returns a new Fiber application instance.
Example
// Default config
app := fiber.New()

// With custom config
app := fiber.New(fiber.Config{
    CaseSensitive: true,
    StrictRouting: true,
    ServerHeader:  "Fiber",
})

​
NewWithCustomCtx

Creates a new App with a custom context factory function. 
func NewWithCustomCtx(fn func(app *App) CustomCtx, config ...Config) *App
​
fn
func(app *App) CustomCtx
Factory function that creates custom context instances.
​
config
Config
Optional configuration for the app.
​
*App
*App
Returns a new Fiber application with custom context support.
Example
type CustomCtx struct {
    fiber.DefaultCtx
}

app := fiber.NewWithCustomCtx(func(app *fiber.App) fiber.CustomCtx {
    return &CustomCtx{
        DefaultCtx: *fiber.NewDefaultCtx(app),
    }
})

​
Routing Methods

​
HTTP Method Handlers

Register routes for specific HTTP methods. 
func (app *App) Get(path string, handlers ...Handler) Router
func (app *App) Head(path string, handlers ...Handler) Router
func (app *App) Post(path string, handlers ...Handler) Router
func (app *App) Put(path string, handlers ...Handler) Router
func (app *App) Delete(path string, handlers ...Handler) Router
func (app *App) Connect(path string, handlers ...Handler) Router
func (app *App) Options(path string, handlers ...Handler) Router
func (app *App) Trace(path string, handlers ...Handler) Router
func (app *App) Patch(path string, handlers ...Handler) Router
​
path
string
The route path pattern.
​
handlers
...Handler
One or more handler functions.
​
Router
Router
Returns the Router instance for chaining.
Example
app.Get("/", func(c fiber.Ctx) error {
    return c.SendString("GET request")
})

app.Post("/user", func(c fiber.Ctx) error {
    return c.SendString("POST request")
})

​
Use

Register middleware or mount sub-applications. 
func (app *App) Use(args ...any) Router
​
args
...any
Can be middleware handlers, path prefix, or sub-applications.
​
Router
Router
Returns the Router instance for chaining.
Example
// Global middleware
app.Use(logger.New())

// Prefixed middleware
app.Use("/api", authMiddleware)

// Mount sub-app
micro := fiber.New()
app.Use("/micro", micro)

​
Group

Create a route group with a common prefix. 
func (app *App) Group(prefix string, handlers ...any) Router
​
prefix
string
The prefix for all routes in the group.
​
handlers
...any
Optional middleware handlers for the group.
​
Router
Router
Returns the group Router instance.
Example
api := app.Group("/api", authMiddleware)

v1 := api.Group("/v1")
v1.Get("/users", getUsers)     // /api/v1/users
v1.Post("/users", createUser)  // /api/v1/users

​
Route

Define routes with a common prefix using a callback function. 
func (app *App) Route(prefix string, fn func(router Router), name ...string) Router
​
prefix
string
The prefix for all routes defined in the callback.
​
fn
func(router Router)
Callback function that receives the router.
​
name
string
Optional name prefix for routes.
​
Router
Router
Returns the Router instance.
Example
app.Route("/test", func(api fiber.Router) {
    api.Get("/foo", handler).Name("foo") // /test/foo (name: test.foo)
    api.Get("/bar", handler).Name("bar") // /test/bar (name: test.bar)
}, "test.")

​
RouteChain

Create a chainable route for handling multiple HTTP methods. 
func (app *App) RouteChain(path string) Register
​
path
string
The route path.
​
Register
Register
Returns a Register interface for chaining method handlers.
Example
app.RouteChain("/api").
    Get(func(c fiber.Ctx) error {
        return c.SendString("GET /api")
    }).
    Post(func(c fiber.Ctx) error {
        return c.SendString("POST /api")
    })

​
Route Information

​
Stack

Returns the raw router stack. 
func (app *App) Stack() [][]*Route
​
[][]*Route
[][]*Route
Returns a 2D array of routes organized by HTTP method.
Example
data, _ := json.MarshalIndent(app.Stack(), "", "  ")
fmt.Println(string(data))

​
GetRoutes

Retrieve all registered routes. 
func (app *App) GetRoutes(filterUseOption ...bool) []Route
​
filterUseOption
bool
When true, filters out routes registered by middleware.
​
[]Route
[]Route
Returns a slice of all routes.
Example
routes := app.GetRoutes(true)
for _, route := range routes {
    fmt.Printf("%s %s\n", route.Method, route.Path)
}

​
GetRoute

Retrieve a route by name. 
func (app *App) GetRoute(name string) Route
​
name
string
The route name.
​
Route
Route
Returns the named route.
Example
app.Get("/", handler).Name("index")
route := app.GetRoute("index")
fmt.Println(route.Path) // "/"

​
Name

Assign a name to the last created route. 
func (app *App) Name(name string) Router
​
name
string
The name to assign to the route.
​
Router
Router
Returns the Router instance for chaining.
Example
app.Get("/users/:id", handler).Name("user.show")

​
HandlersCount

Returns the number of registered handlers. 
func (app *App) HandlersCount() uint32
​
uint32
uint32
Returns the total handler count.

​
MountPath

Returns the mount path of the application. 
func (app *App) MountPath() string
​
string
string
Returns the mount path or empty string if not mounted.
Example
subApp := fiber.New()
app.Use("/api", subApp)
fmt.Println(subApp.MountPath()) // "/api"

​
Configuration & State

​
Config

Returns the app configuration. 
func (app *App) Config() Config
​
Config
Config
Returns a copy of the app configuration.

​
Handler

Returns the fasthttp request handler. 
func (app *App) Handler() fasthttp.RequestHandler
​
fasthttp.RequestHandler
fasthttp.RequestHandler
Returns the handler compatible with fasthttp server.

​
ErrorHandler

Executes the configured error handler. 
func (app *App) ErrorHandler(ctx Ctx, err error) error
​
ctx
Ctx
The request context.
​
err
error
The error to handle.
​
error
error
Returns an error if the handler fails.

​
Server Lifecycle

​
Listen

Start the server on the specified address. 
func (app *App) Listen(addr string, config ...ListenConfig) error
​
addr
string
The address to listen on (e.g., “:3000”).
​
config
ListenConfig
Optional listen configuration.
​
error
error
Returns an error if the server fails to start.
Example
if err := app.Listen(":3000"); err != nil {
    log.Fatal(err)
}

​
Shutdown

Gracefully shutdown the server. 
func (app *App) Shutdown() error
​
error
error
Returns an error if shutdown fails.

​
Test

Test the app with a simulated HTTP request. 
func (app *App) Test(req *http.Request, config ...TestConfig) (*http.Response, error)
​
req
*http.Request
The HTTP request to test.
​
config
TestConfig
Optional test configuration (timeout, etc.).
​
*http.Response
*http.Response
Returns the HTTP response.
​
error
error
Returns an error if the test fails.
Example
req := httptest.NewRequest("GET", "/", nil)
resp, err := app.Test(req)
if err != nil {
    log.Fatal(err)
}

​
Hooks

​
Hooks

Returns the hooks manager. 
func (app *App) Hooks() *Hooks
​
*Hooks
*Hooks
Returns the hooks manager instance.
Example
app.Hooks().OnListen(func(data fiber.ListenData) error {
    fmt.Printf("Listening on %s:%s\n", data.Host, data.Port)
    return nil
})

​
Advanced

​
RegisterCustomBinder

Register a custom binder for request body parsing. 
func (app *App) RegisterCustomBinder(binder CustomBinder)
​
binder
CustomBinder
The custom binder implementation.

​
RegisterCustomConstraint

Register a custom route constraint. 
func (app *App) RegisterCustomConstraint(constraint CustomConstraint)
​
constraint
CustomConstraint
The custom constraint implementation.

​
RebuildTree

Rebuild the routing tree (for dynamic route registration). 
func (app *App) RebuildTree() *App
​
*App
*App
Returns the app instance for chaining.
This method is not thread-safe and should only be used in development mode.

​
RemoveRoute

Remove a route by path. 
func (app *App) RemoveRoute(path string, methods ...string)
​
path
string
The route path to remove.
​
methods
...string
Optional HTTP methods. If omitted, removes for all methods.

​
GetString

Returns a string respecting the Immutable setting. 
func (app *App) GetString(s string) string
​
s
string
The input string.
​
string
string
Returns the string (cloned if Immutable is enabled).

​
GetBytes

Returns a byte slice respecting the Immutable setting. 
func (app *App) GetBytes(b []byte) []byte
​
b
[]byte
The input byte slice.
​
[]byte
[]byte
Returns the byte slice (cloned if Immutable is enabled).

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