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🔌 Routing

Handlers​

Registers a route bound to a specific HTTP method.

Signatures
// HTTP methods
func (app *App) Get(path string, handler Handler, handlers ...Handler) Router
func (app *App) Head(path string, handler Handler, handlers ...Handler) Router
func (app *App) Post(path string, handler Handler, handlers ...Handler) Router
func (app *App) Put(path string, handler Handler, handlers ...Handler) Router
func (app *App) Delete(path string, handler Handler, handlers ...Handler) Router
func (app *App) Connect(path string, handler Handler, handlers ...Handler) Router
func (app *App) Options(path string, handler Handler, handlers ...Handler) Router
func (app *App) Trace(path string, handler Handler, handlers ...Handler) Router
func (app *App) Patch(path string, handler Handler, handlers ...Handler) Router

// Add allows you to specify a method as value
func (app *App) Add(method, path string, handler Handler, handlers ...Handler) Router

// All will register the route on all HTTP methods
// Almost the same as app.Use but not bound to prefixes
func (app *App) All(path string, handler Handler, handlers ...Handler) Router
Examples
// Simple GET handler
app.Get("/api/list", func(c fiber.Ctx) error {
    return c.SendString("I'm a GET request!")
})

// Simple POST handler
app.Post("/api/register", func(c fiber.Ctx) error {
    return c.SendString("I'm a POST request!")
})
#Use

Can be used for middleware packages and prefix catchers. These routes will only match the beginning of each path i.e. /john will match /john/doe, /johnnnnn etc

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

// Different usage variations
func (app *App) Use(handler Handler, handlers ...Handler) Router
func (app *App) Use(path string, handler Handler, handlers ...Handler) Router
func (app *App) Use(paths []string, handler Handler, handlers ...Handler) Router
func (app *App) Use(path string, app *App) Router
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 
app.Use("/api", func(c fiber.Ctx) error {
    c.Set("X-Custom-Header", random.String(32))
    return c.Next()
}, func(c fiber.Ctx) error {
    return c.Next()
})

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

Paths​

A route path paired with an HTTP method defines an endpoint. It can be a plain string or a pattern.

Examples of route paths based on strings​

// This route path will match requests to the root route, "/":
app.Get("/", func(c fiber.Ctx) error {
    return c.SendString("root")
})

// This route path will match requests to "/about":
app.Get("/about", func(c fiber.Ctx) error {
    return c.SendString("about")
})

// This route path will match requests to "/random.txt":
app.Get("/random.txt", func(c fiber.Ctx) error {
    return c.SendString("random.txt")
})

As with the Express.js framework, the order in which routes are declared matters. Routes are evaluated sequentially, so more specific paths should appear before those with variables.

info

Place routes with variable parameters after fixed paths to avoid unintended matches.

Parameters​

Route parameters are dynamic segments in a path, either named or unnamed, used to capture values from the URL. Retrieve them with the Params function using the parameter name or, for unnamed parameters, the wildcard (*) or plus (+) symbol with an index.

The characters :, +, and * introduce parameters.

Use * or + to capture segments greedily.

You can define optional parameters by appending ? to a named segment. The + sign is greedy and required, while * acts as an optional greedy wildcard.

Example of defining routes with route parameters​

// Parameters
app.Get("/user/:name/books/:title", func(c fiber.Ctx) error {
    fmt.Fprintf(c, "%s\n", c.Params("name"))
    fmt.Fprintf(c, "%s\n", c.Params("title"))
    return nil
})
// Plus - greedy - not optional
app.Get("/user/+", func(c fiber.Ctx) error {
    return c.SendString(c.Params("+"))
})

// Optional parameter
app.Get("/user/:name?", func(c fiber.Ctx) error {
    return c.SendString(c.Params("name"))
})

// Wildcard - greedy - optional
app.Get("/user/*", func(c fiber.Ctx) error {
    return c.SendString(c.Params("*"))
})

// This route path will match requests to "/v1/some/resource/name:customVerb", since the parameter character is escaped
app.Get(`/v1/some/resource/name\:customVerb`, func(c fiber.Ctx) error {
    return c.SendString("Hello, Community")
})
info

The hyphen (-) and dot (.) are treated literally, so you can combine them with route parameters.

info

Escape special parameter characters with \\ to treat them literally. This technique is useful for custom methods like those in the Google API Design Guide. Wrap routes in backticks to keep escape sequences clear.

// http://localhost:3000/plantae/prunus.persica
app.Get("/plantae/:genus.:species", func(c fiber.Ctx) error {
    fmt.Fprintf(c, "%s.%s\n", c.Params("genus"), c.Params("species"))
    return nil // prunus.persica
})
// http://localhost:3000/flights/LAX-SFO
app.Get("/flights/:from-:to", func(c fiber.Ctx) error {
    fmt.Fprintf(c, "%s-%s\n", c.Params("from"), c.Params("to"))
    return nil // LAX-SFO
})

Fiber's router detects when these characters belong to the literal path and handles them accordingly.

// http://localhost:3000/shop/product/color:blue/size:xs
app.Get("/shop/product/color::color/size::size", func(c fiber.Ctx) error {
    fmt.Fprintf(c, "%s:%s\n", c.Params("color"), c.Params("size"))
    return nil // blue:xs
})

You can chain multiple named or unnamed parameters—including wildcard and plus segments—giving the router greater flexibility.

// GET /@v1
// Params: "sign" -> "@", "param" -> "v1"
app.Get("/:sign:param", handler)

// GET /api-v1
// Params: "name" -> "v1"
app.Get("/api-:name", handler)

// GET /customer/v1/cart/proxy
// Params: "*1" -> "customer/", "*2" -> "/cart"
app.Get("/*v1*/proxy", handler)

// GET /v1/brand/4/shop/blue/xs
// Params: "*1" -> "brand/4", "*2" -> "blue/xs"
app.Get("/v1/*/shop/*", handler)

Fiber's routing is inspired by Express but intentionally omits regular expression routes due to their performance cost. You can try similar patterns using the Express route tester (v0.1.7).

Constraints​

Route constraints execute when a match has occurred to the incoming URL and the URL path is tokenized into route values by parameters. The feature was introduced in v2.37.0 and inspired by .NET Core.

caution

Constraints aren't validation for parameters. If constraints aren't valid for a parameter value, Fiber returns 404 handler.

ConstraintExampleExample matches
int:id<int>123456789, -123456789
bool:active<bool>true,false
guid:id<guid>CD2C1638-1638-72D5-1638-DEADBEEF1638
float:weight<float>1.234, -1,001.01e8
minLen(value):username<minLen(4)>Test (must be at least 4 characters)
maxLen(value):filename<maxLen(8)>MyFile (must be no more than 8 characters
len(length):filename<len(12)>somefile.txt (exactly 12 characters)
min(value):age<min(18)>19 (Integer value must be at least 18)
max(value):age<max(120)>91 (Integer value must be no more than 120)
range(min,max):age<range(18,120)>91 (Integer value must be at least 18 but no more than 120)
alpha:name<alpha>Rick (String must consist of one or more alphabetical characters, a-z and case-insensitive)
datetime:dob<datetime(2006\\-01\\-02)>2005-11-01
regex(expression):date<regex(\d{4}-\d{2}-\d{2})>2022-08-27 (Must match regular expression)

Examples​

app.Get("/:test<min(5)>", func(c fiber.Ctx) error {
    return c.SendString(c.Params("test"))
})

// curl -X GET http://localhost:3000/12
// 12

// curl -X GET http://localhost:3000/1
// Not Found
caution

Prefix routing characters with \\ when using the datetime constraint (*, +, ?, :, /, <, >, ;, (, )), to avoid misparsing.

Optional Parameter Example​

You can impose constraints on optional parameters as well.

app.Get("/:test<int>?", func(c fiber.Ctx) error {
  return c.SendString(c.Params("test"))
})
// curl -X GET http://localhost:3000/42
// 42
// curl -X GET http://localhost:3000/
//
// curl -X GET http://localhost:3000/7.0
// Not Found

Custom Constraint​

Custom constraints can be added to Fiber using the app.RegisterCustomConstraint method. Your constraints have to be compatible with the CustomConstraint interface.

caution

Attention, custom constraints can now override built-in constraints. If a custom constraint has the same name as a built-in constraint, the custom constraint will be used instead. This allows for more flexibility in defining route parameter constraints.

Add external constraints when you need stricter rules, such as verifying that a parameter is a valid ULID.

// CustomConstraint is an interface for custom constraints
type CustomConstraint interface {
    // Name returns the name of the constraint.
    // This name is used in the constraint matching.
    Name() string

    // Execute executes the constraint.
    // It returns true if the constraint is matched and right.
    // param is the parameter value to check.
    // args are the constraint arguments.
    Execute(param string, args ...string) bool
}

You can check the example below:

type UlidConstraint struct {
    fiber.CustomConstraint
}

func (*UlidConstraint) Name() string {
    return "ulid"
}

func (*UlidConstraint) Execute(param string, args ...string) bool {
    _, err := ulid.Parse(param)
    return err == nil
}

func main() {
    app := fiber.New()
    app.RegisterCustomConstraint(&UlidConstraint{})

    app.Get("/login/:id<ulid>", func(c fiber.Ctx) error {
        return c.SendString("...")
    })

    app.Listen(":3000")

    // /login/01HK7H9ZE5BFMK348CPYP14S0Z -> 200
    // /login/12345 -> 404
}

Middleware​

Functions that are designed to make changes to the request or response are called middleware functions. The Next is a Fiber router function, when called, executes the next function that matches the current route.

Example of a middleware function​

app.Use(func(c fiber.Ctx) error {
    // Set a custom header on all responses:
    c.Set("X-Custom-Header", "Hello, World")

    // Go to next middleware:
    return c.Next()
})

app.Get("/", func(c fiber.Ctx) error {
    return c.SendString("Hello, World!")
})

Use method path is a mount, or prefix path, and limits middleware to only apply to any paths requested that begin with it.

Constraints on Adding Routes Dynamically​

caution

Adding routes dynamically after the application has started is not supported due to design and performance considerations. Make sure to define all your routes before the application starts.

Grouping​

If you have many endpoints, you can organize your routes using Group.

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

    api := app.Group("/api", middleware) // /api

    v1 := api.Group("/v1", middleware)   // /api/v1
    v1.Get("/list", handler)             // /api/v1/list
    v1.Get("/user", handler)             // /api/v1/user

    v2 := api.Group("/v2", middleware)   // /api/v2
    v2.Get("/list", handler)             // /api/v2/list
    v2.Get("/user", handler)             // /api/v2/user

    log.Fatal(app.Listen(":3000"))
}

More information about this in our Grouping Guide