What's New in Fiber v3

When most teams read a "what's new" post, they are usually looking for one of two things.

The first is curiosity: what did the framework ship? The second is risk management: what do we need to change first, and what can wait until later?

For Fiber v3, the second question is the important one.

The release includes a lot of meaningful work, but a few parts have outsized impact in real services: request binding, lifecycle hooks, listen configuration, handler compatibility, context improvements, and the new extractors package.

This article is intentionally written for that reality. You should be able to read this, open one service in your codebase, and know exactly what to migrate first and why.

Before You Start: Go 1.25 and the Migration CLI

Fiber v3 requires Go 1.25 or later. Update your toolchain before upgrading so the module go directive and standard library features align with the new minimum version.

Before you dive into manual refactors, use the migration helper that ships with the Fiber CLI. It can take care of a large part of repetitive upgrade work and gives you a cleaner baseline for the manual improvements described in this post.

go install github.com/gofiber/cli/fiber@latest
fiber migrate --to v3.0.0

You still need to review and test the result, but using the migrator first usually saves time and reduces mechanical errors.

Start with an Upgrade Strategy, Not a Feature Tour

The teams that struggle with migrations usually do one thing wrong: they migrate randomly.

Someone updates one handler. Someone else copies a new example into another package. A third person keeps old parsing logic because "it still works." After two sprints, the codebase is half old, half new, and debugging gets harder.

Fiber v3 rewards the opposite approach:

1. standardize request input first
2. standardize lifecycle behavior second
3. modernize client and boundary layers third

If you do that in order, you get consistency fast and avoid expensive refactors later.

1) Unified Binding: The Single Biggest Migration Win

One of the most important v3 changes is the unified binding system. In v2, request parsing was split across BodyParser, ParamsInt, QueryBool, CookieParser, and individual c.Query() / c.Get() calls. Each method had its own behavior, and handlers ended up with inconsistent parsing styles.

v3 replaces all of that with c.Bind():

type UserInput struct {
    ID      int    `uri:"id" json:"id" query:"id"`
    Name    string `json:"name" form:"name" query:"name"`
    Role    string `header:"X-Role"`
    Session string `cookie:"session_id"`
}

app.Post("/users/:id", func(c fiber.Ctx) error {
    in := new(UserInput)

    if err := c.Bind().All(in); err != nil {
        return c.Status(fiber.StatusBadRequest).JSON(fiber.Map{"error": err.Error()})
    }

    return c.JSON(in)
})

Bind().All() applies sources in a fixed precedence: URI params, body, query, headers, cookies. That removes ambiguity in mixed-source endpoints. There are also focused methods like Bind().Body(), Bind().Query(), Bind().Header(), Bind().Cookie(), and Bind().URI() when you only need one source.

v3 binding also supports built-in validation, default values via default: tags, and custom binders for formats like YAML. Native CBOR and MsgPack support is included alongside JSON, XML, and form data.

For a deep dive, see Binding in Practice.

2) Lifecycle Hooks: Deploy Confidence

Most APIs are not just request handlers. They run workers, queues, cleanup logic, telemetry flushes, and startup checks. In v2, the main lifecycle hook was OnShutdown, but you could not distinguish "before the server stops accepting" from "after everything is drained."

v3 replaces OnShutdown with explicit pre/post phases and adds startup message customization:

app.Hooks().OnPreStartupMessage(func(sm *fiber.PreStartupMessageData) error {
    sm.BannerHeader = "MY-SERVICE " + sm.Version
    sm.AddInfo("env", "Environment", os.Getenv("APP_ENV"))
    return nil
})

app.Hooks().OnPreShutdown(func() error {
    log.Println("stopping workers")
    return stopConsumers()
})

app.Hooks().OnPostShutdown(func(err error) error {
    log.Printf("shutdown done, err=%v", err)
    return flushMetrics()
})

v3 also adds registration-time hooks (OnRoute, OnGroup, OnName, OnMount) that fire when routes and sub-apps are registered, useful for building route registries and enforcing naming conventions.

For a deep dive, see Hooks Guide for Clean Lifecycles.

3) Listen: Cleaner Configuration

Fiber v3 tightens listen behavior and moves several config properties from fiber.Config to ListenConfig: DisableStartupMessage, EnablePrefork, EnablePrintRoutes, and ListenerNetwork.

Unix sockets are a good example of the improvement. In v2 you had to manually delete old socket files, listen on a unix network, and chmod the socket in an OnListen hook. v3 handles it:

app := fiber.New()
app.Listen("app.sock", fiber.ListenConfig{
    ListenerNetwork:    fiber.NetworkUnix,
    UnixSocketFileMode: 0770,
})

v3 also adds native TLS AutoCert support with Let's Encrypt and ACME providers:

certManager := &autocert.Manager{
    Prompt:     autocert.AcceptTOS,
    HostPolicy: autocert.HostWhitelist("example.com"),
    Cache:      autocert.DirCache("./certs"),
}

app.Listen(":443", fiber.ListenConfig{
    AutoCertManager: certManager,
})

4) Handler Compatibility: Migrate Without Rewriting

If your org has a large net/http or fasthttp surface, full rewrites are often unrealistic. Fiber v3 helps by accepting 17 different handler signatures directly in the router, including native Fiber, net/http, fasthttp, and Express-style Req/Res callbacks:

// net/http handler — no adapter needed
app.Get("/legacy", func(w http.ResponseWriter, r *http.Request) {
    w.WriteHeader(http.StatusOK)
    _, _ = w.Write([]byte("legacy route"))
})

// Express-style with next callback
app.Use(func(req fiber.Req, res fiber.Res, next func() error) error {
    req.Headers().Set("X-Via", "compat")
    return next()
})

This enables route-by-route migration. You modernize high-value endpoints first while keeping legacy handlers operational.

v3 also adds RouteChain for Express-style route declaration and automatically registers HEAD routes for every GET route.

For a deep dive, see Handler Compatibility in the New Router.

5) Context Implements context.Context

fiber.Ctx now satisfies Go's context.Context interface. This eliminates the v2 pattern of calling c.UserContext() to bridge between Fiber and the standard library:

// v2: manual bridging
ctx := c.UserContext()
rows, err := db.QueryContext(ctx, "SELECT ...")

// v3: pass Fiber context directly
rows, err := db.QueryContext(c, "SELECT ...")

Deadline propagation, cancellation, and request-scoped values all work natively. Libraries that accept context.Context now get proper request lifecycle integration without boilerplate.

v3 also adds many new context methods: Drop() for silent connection termination (DDoS mitigation), End() for immediate response flush, SendEarlyHints() for HTTP 103 preloading, AutoFormat() for content negotiation, SendStreamWriter() for SSE and streaming, and numerous inspection helpers like IsJSON(), IsWebSocket(), HasBody(), and IsPreflight().

For a deep dive on context extensions, see Custom Context in Practice.

6) Generic Functions: Type-Safe Parameter Access

v3 introduces generic helper functions that replace the old type-specific methods:

// v2: ParamsInt, QueryBool, QueryFloat — individual methods
id, _ := c.ParamsInt("id")

// v3: generic functions with type inference and defaults
id := fiber.Params[int](c, "id", 0)
age := fiber.Query[int](c, "age", 18)
agent := fiber.GetReqHeader[string](c, "User-Agent", "Unknown")

fiber.Locals[T] provides type-safe local value storage, and fiber.Convert[T] handles custom conversions with fallback defaults.

7) Extractors Package: Shared Middleware Policy

The new extractors package consolidates value extraction that was previously duplicated across middleware. Instead of each middleware implementing its own token/key lookup, they now share a common API:

app.Use(keyauth.New(keyauth.Config{
    Extractor: extractors.Chain(
        extractors.FromAuthHeader("Bearer"),
        extractors.FromHeader("X-API-Key"),
        extractors.FromCookie("api_key"),
    ),
}))

FromAuthHeader includes strict RFC 9110/7235 validation. The chain tries each source in order and returns the first success, making extraction policy explicit and auditable.

For a deep dive, see Extractors Guide for Middleware.

8) Custom Route Constraints

Instead of validating every path parameter deep in handlers, you can move constraint logic to routing:

type UlidConstraint struct{ fiber.CustomConstraint }

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

app.RegisterCustomConstraint(&UlidConstraint{})
app.Get("/users/:id<ulid>", func(c fiber.Ctx) error {
    return c.SendString("valid id: " + c.Params("id"))
})

Malformed IDs never reach business logic. The route returns 404 before the handler runs.

9) Cookie and RFC Improvements

v3 makes several protocol improvements that reduce interoperability incidents:

• Auto-Secure for SameSite=None: When you set SameSite=None, Fiber automatically adds Secure=true as required by RFC 6265bis and modern browsers
• CHIPS support: Partitioned cookies for third-party contexts via Partitioned: true
• Non-ASCII filenames: Attachment and Download use RFC 6266/8187 encoding
• Default redirect status: Changed from 302 to 303 for more consistent browser behavior

For a deep dive, see RFC Conformance in Practice.

10) Storage, Client, and Middleware Updates

Storage: All storage adapters now include WithContext methods (GetWithContext, SetWithContext, DeleteWithContext, ResetWithContext) for cancellation, timeout control, and request-scoped behavior.

Client: The client package has been completely rebuilt with cookie jar support, request/response hooks, retry configuration, proxy support, and debug mode. See New Client Deep Dive.

Middleware changes worth noting:

• app.Static() removed — use the static middleware instead
• Filesystem middleware removed — static middleware covers both
• Middleware data now uses FromContext() functions (e.g., requestid.FromContext(c)) instead of string-based c.Locals() keys
• Cache middleware: RFC-compliant Age header, MaxBytes limit, non-cacheable status filtering
• Compression: zstd support added alongside gzip, deflate, and brotli
• CORS: fields changed from comma-separated strings to slices
• Healthcheck: simplified to single generic probe handler, no auto-registered endpoints
• BasicAuth: passwords must be hashed, authorizer receives fiber.Ctx
• Services: new feature for managing application dependencies (databases, caches) as first-class service objects

11) Stricter Middleware Prefix Matching

Middleware prefix matching is now stricter: partial matches must end at a slash boundary or be an exact match. This prevents /api middleware from running on /apiv1:

app.Use("/api", apiMiddleware)  // runs for /api and /api/... only

Multiple prefixes are supported, and sub-apps mount with app.Use() instead of the removed app.Mount().

Where to Practice These Changes

For the complete list of v3 changes, keep the official page open while migrating: What's New in Fiber v3

• CRUD + binding patterns: gofiber/recipes/gorm-postgres
• Static + middleware behavior: gofiber/recipes/file-server
• SPA fallback behavior: gofiber/recipes/react-router
• API docs integration: gofiber/recipes/swagger

If you only do one thing this week: pick one service, enforce a single binding style, and add lifecycle hooks around startup/shutdown. That alone delivers a measurable improvement in maintainability.