📦 Fiber

Server start

New

This method creates a new App named instance. You can pass optional config when creating a new instance.

Signature

func New(config ...Config) *App

Example

// Default config
app := fiber.New()

// ...

Config

You can pass an optional Config when creating a new Fiber instance.

Example

// Custom config
app := fiber.New(fiber.Config{
    CaseSensitive: true,
    StrictRouting: true,
    ServerHeader:  "Fiber",
    AppName: "Test App v1.0.1",
})

// ...

Config fields

Property	Type	Description	Default
AppName	string	Sets the application name used in logs and the Server header	""
BodyLimit	int	Sets the maximum allowed size for a request body. Zero or negative values fall back to the default limit. If the size exceeds the configured limit, it sends 413 - Request Entity Too Large response.	4 * 1024 * 1024
CaseSensitive	bool	When enabled, /Foo and /foo are different routes. When disabled, /Foo and /foo are treated the same.	false
ColorScheme	Colors	You can define custom color scheme. They'll be used for startup message, route list and some middlewares.	DefaultColors
CompressedFileSuffixes	map[string]string	Adds a suffix to the original file name and tries saving the resulting compressed file under the new file name.	{"gzip": ".fiber.gz", "br": ".fiber.br", "zstd": ".fiber.zst"}
Concurrency	int	Maximum number of concurrent connections.	256 * 1024
DisableDefaultContentType	bool	When true, omits the default Content-Type header from the response.	false
DisableDefaultDate	bool	When true, omits the Date header from the response.	false
DisableHeaderNormalizing	bool	By default all header names are normalized: conteNT-tYPE -> Content-Type	false
DisableKeepalive	bool	Disables keep-alive connections so the server closes each connection after the first response.	false
DisablePreParseMultipartForm	bool	Will not pre parse Multipart Form data if set to true. This option is useful for servers that desire to treat multipart form data as a binary blob, or choose when to parse the data.	false
EnableIPValidation	bool	If set to true, c.IP() and c.IPs() will validate IP addresses before returning them. Also, c.IP() will return only the first valid IP rather than just the raw header value that may be a comma separated string. WARNING: There is a small performance cost to doing this validation. Keep disabled if speed is your only concern and your application is behind a trusted proxy that already validates this header.	false
EnableSplittingOnParsers	bool	Splits query, body, and header parameters on commas when enabled. For example, /api?foo=bar,baz becomes foo[]=bar&foo[]=baz.	false
TrustProxy	bool	When true, Fiber validates the proxy IP against TrustProxyConfig.Proxies. By default, c.Protocol(), c.IP(), and c.Hostname() read values from standard X-Forwarded headers. If the remote IP matches a trusted proxy, these methods behave as if TrustProxy were disabled. Otherwise, c.Protocol() reflects the connection scheme, c.IP() uses RemoteIP() from Fasthttp, and c.Hostname() uses fasthttp.Request.URI().Host()	false

|

ErrorHandler

| ErrorHandler | ErrorHandler is executed when an error is returned from fiber.Handler. Mounted fiber error handlers are retained by the top-level app and applied on prefix associated requests. | DefaultErrorHandler | |

GETOnly

| bool | Rejects all non-GET requests if set to true. This option is useful as anti-DoS protection for servers accepting only GET requests. The request size is limited by ReadBufferSize if GETOnly is set. | false | |

IdleTimeout

| time.Duration | The maximum amount of time to wait for the next request when keep-alive is enabled. If IdleTimeout is zero, the value of ReadTimeout is used. | nil | |

Immutable

| bool | When enabled, all values returned by context methods are immutable. By default, they are valid until you return from the handler; see issue #185. | false | |

JSONEncoder

| utils.JSONMarshal | Allowing for flexibility in using another json library for encoding. | json.Marshal | |

JSONDecoder

| utils.JSONUnmarshal | Allowing for flexibility in using another json library for decoding. | json.Unmarshal | |

CBOREncoder

| utils.CBORMarshal | Allowing for flexibility in using another cbor library for encoding. | *binder.UnimplementedCborMarshal | |

CBORDecoder

| utils.CBORUnmarshal | Allowing for flexibility in using another cbor library for decoding. | *binder.UnimplementedCborUnmarshal | |

MsgpackEncoder

| utils.MsgpackMarshal | Allowing for flexibility in using another msgpack library for encoding. | *binder.UnimplementedMsgpackMarshal | |

MsgpackDecoder

| utils.MsgpackUnmarshal | Allowing for flexibility in using another msgpack library for decoding. | *binder.UnimplementedMsgpackUnmarshal | |

PassLocalsToViews

| bool | PassLocalsToViews Enables passing of the locals set on a fiber.Ctx to the template engine. See our Template Middleware for supported engines. | false | |

ProxyHeader

| string | This will enable c.IP() to return the value of the given header key. By default c.IP()will return the Remote IP from the TCP connection, this property can be useful if you are behind a load balancer e.g. X-Forwarded-*. | "" | |

ReadBufferSize

| int | per-connection buffer size for requests' reading. This also limits the maximum header size. Increase this buffer if your clients send multi-KB RequestURIs and/or multi-KB headers (for example, BIG cookies). | 4096 | |

ReadTimeout

| time.Duration | The amount of time allowed to read the full request, including the body. The default timeout is unlimited. | nil | |

ReduceMemoryUsage

| bool | Aggressively reduces memory usage at the cost of higher CPU usage if set to true. | false | |

RequestMethods

| []string | RequestMethods provides customizability for HTTP methods. You can add/remove methods as you wish. | DefaultMethods | |

ServerHeader

| string | Enables the Server HTTP header with the given value. | "" | |

StreamRequestBody

| bool | StreamRequestBody enables request body streaming, and calls the handler sooner when given body is larger than the current limit. | false | |

StrictRouting

| bool | When enabled, the router treats /foo and /foo/ as different. Otherwise, the router treats /foo and /foo/ as the same. | false | |

StructValidator

| StructValidator | If you want to validate header/form/query... automatically when to bind, you can define struct validator. Fiber doesn't have default validator, so it'll skip validator step if you don't use any validator. | nil | |

TrustProxyConfig

| TrustProxyConfig | Configure trusted proxy IP's. Look at TrustProxy doc.

TrustProxyConfig.Proxies can take IP or IP range addresses. | nil | |

UnescapePath

| bool | Converts all encoded characters in the route back before setting the path for the context, so that the routing can also work with URL encoded special characters | false | |

Views

| Views | Views is the interface that wraps the Render function. See our Template Middleware for supported engines. | nil | |

ViewsLayout

| string | Views Layout is the global layout for all template render until override on Render function. See our Template Middleware for supported engines. | "" | |

WriteBufferSize

| int | Per-connection buffer size for responses' writing. | 4096 | |

WriteTimeout

| time.Duration | The maximum duration before timing out writes of the response. The default timeout is unlimited. | nil | |

XMLEncoder

| utils.XMLMarshal | Allowing for flexibility in using another XML library for encoding. | xml.Marshal | |

XMLDecoder

| utils.XMLUnmarshal | Allowing for flexibility in using another XML library for decoding. | xml.Unmarshal |

Server listening

Config

You can pass an optional ListenConfig when calling the Listen or Listener method.

Example

// Custom config
app.Listen(":8080", fiber.ListenConfig{
    EnablePrefork: true,
    DisableStartupMessage: true,
})

Config fields

Property	Type	Description	Default
BeforeServeFunc	func(app *App) error	Allows customizing and accessing fiber app before serving the app.	nil
CertClientFile	string	Path of the client certificate. If you want to use mTLS, you must enter this field.	""
CertFile	string	Path of the certificate file. If you want to use TLS, you must enter this field.	""
CertKeyFile	string	Path of the certificate's private key. If you want to use TLS, you must enter this field.	""
DisableStartupMessage	bool	When set to true, it will not print out the «Fiber» ASCII art and listening address.	false
EnablePrefork	bool	When set to true, this will spawn multiple Go processes listening on the same port.	false
EnablePrintRoutes	bool	If set to true, will print all routes with their method, path, and handler.	false
GracefulContext	context.Context	Field to shutdown Fiber by given context gracefully.	nil
ShutdownTimeout	time.Duration	Specifies the maximum duration to wait for the server to gracefully shutdown. When the timeout is reached, the graceful shutdown process is interrupted and forcibly terminated, and the context.DeadlineExceeded error is passed to the OnPostShutdown callback. Set to 0 to disable the timeout and wait indefinitely.	10 * time.Second
ListenerAddrFunc	func(addr net.Addr)	Allows accessing and customizing net.Listener.	nil
ListenerNetwork	string	Known networks are "tcp", "tcp4" (IPv4-only), "tcp6" (IPv6-only), "unix" (Unix Domain Sockets). WARNING: When prefork is set to true, only "tcp4" and "tcp6" can be chosen.	tcp4
UnixSocketFileMode	os.FileMode	FileMode to set for Unix Domain Socket (ListenerNetwork must be "unix")	0770
TLSConfigFunc	func(tlsConfig *tls.Config)	Allows customizing tls.Config as you want.	nil
AutoCertManager	*autocert.Manager	Manages TLS certificates automatically using the ACME protocol. Enables integration with Let's Encrypt or other ACME-compatible providers.	nil
TLSMinVersion	uint16	Allows customizing the TLS minimum version.	tls.VersionTLS12

Listen

Listen serves HTTP requests from the given address.

Signature

func (app *App) Listen(addr string, config ...ListenConfig) error

Examples

// Listen on port :8080 
app.Listen(":8080")

// Listen on port :8080 with Prefork 
app.Listen(":8080", fiber.ListenConfig{EnablePrefork: true})

// Custom host
app.Listen("127.0.0.1:8080")

Prefork

Prefork is a feature that allows you to spawn multiple Go processes listening on the same port. This can be useful for scaling across multiple CPU cores.

Examples

app.Listen(":8080", fiber.ListenConfig{EnablePrefork: true})

This distributes the incoming connections between the spawned processes and allows more requests to be handled simultaneously.

TLS

TLS serves HTTPs requests from the given address using certFile and keyFile paths to as TLS certificate and key file.

Examples

app.Listen(":443", fiber.ListenConfig{CertFile: "./cert.pem", CertKeyFile: "./cert.key"})

TLS with certificate

Examples

app.Listen(":443", fiber.ListenConfig{CertClientFile: "./ca-chain-cert.pem"})

TLS with certFile, keyFile and clientCertFile

Examples

app.Listen(":443", fiber.ListenConfig{CertFile: "./cert.pem", CertKeyFile: "./cert.key", CertClientFile: "./ca-chain-cert.pem"})

TLS AutoCert support (ACME / Let's Encrypt)

Provides automatic access to certificates management from Let's Encrypt and any other ACME-based providers.

Examples

// Certificate manager
certManager := &autocert.Manager{
    Prompt: autocert.AcceptTOS,
    // Replace with your domain name
    HostPolicy: autocert.HostWhitelist("example.com"),
    // Folder to store the certificates
    Cache: autocert.DirCache("./certs"),
}

app.Listen(":444", fiber.ListenConfig{
    AutoCertManager:    certManager,
})

Listener

You can pass your own net.Listener using the Listener method. This method can be used to enable TLS/HTTPS with a custom tls.Config.

Signature

func (app *App) Listener(ln net.Listener, config ...ListenConfig) error

Examples

ln, _ := net.Listen("tcp", ":3000")

cer, _:= tls.LoadX509KeyPair("server.crt", "server.key")

ln = tls.NewListener(ln, &tls.Config{Certificates: []tls.Certificate{cer}})

app.Listener(ln)

Server

Server returns the underlying fasthttp server

Signature

func (app *App) Server() *fasthttp.Server

Examples

func main() {
    app := fiber.New()

    app.Server().MaxConnsPerIP = 1

    // ...
}

Server Shutdown

Shutdown gracefully shuts down the server without interrupting any active connections. Shutdown works by first closing all open listeners and then waits indefinitely for all connections to return to idle before shutting down.

ShutdownWithTimeout will forcefully close any active connections after the timeout expires.

ShutdownWithContext shuts down the server including by force if the context's deadline is exceeded. Shutdown hooks will still be executed, even if an error occurs during the shutdown process, as they are deferred to ensure cleanup happens regardless of errors.

func (app *App) Shutdown() error
func (app *App) ShutdownWithTimeout(timeout time.Duration) error
func (app *App) ShutdownWithContext(ctx context.Context) error

Helper functions

NewError

NewError creates a new HTTPError instance with an optional message.

Signature

func NewError(code int, message ...string) *Error

Example

app.Get("/", func(c fiber.Ctx) error {
    return fiber.NewError(782, "Custom error message")
})

NewErrorf

NewErrorf creates a new HTTPError instance with an optional formatted message.

Signature

func NewErrorf(code int, message ...any) *Error

Example

app.Get("/", func(c fiber.Ctx) error {
    return fiber.NewErrorf(782, "Custom error %s", "message")
})

IsChild

IsChild determines if the current process is a result of Prefork.

Signature

func IsChild() bool

Example

// Config app
app := fiber.New()

app.Get("/", func(c fiber.Ctx) error {
    if !fiber.IsChild() {
        fmt.Println("I'm the parent process")
    } else {
        fmt.Println("I'm a child process")
    }
    return c.SendString("Hello, World!")
})

// ...

// With prefork enabled, the parent process will spawn child processes
app.Listen(":8080", fiber.ListenConfig{EnablePrefork: true})