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The Early Data middleware for Fiber adds support for TLS 1.3's early data ("0-RTT") feature. Citing RFC 8446, when a client and server share a PSK, TLS 1.3 allows clients to send data on the first flight ("early data") to speed up the request, effectively reducing the regular 1-RTT request to a 0-RTT request.

Make sure to enable fiber's EnableTrustedProxyCheck config option before using this middleware in order to not trust bogus HTTP request headers of the client.

Also be aware that enabling support for early data in your reverse proxy (e.g. nginx, as done with a simple ssl_early_data on;) makes requests replayable. Refer to the following documents before continuing:

By default, this middleware allows early data requests on safe HTTP request methods only and rejects the request otherwise, i.e. aborts the request before executing your handler. This behavior can be controlled by the AllowEarlyData config option. Safe HTTP methods — GET, HEAD, OPTIONS and TRACE — should not modify a state on the server.


func New(config ...Config) fiber.Handler
func IsEarlyData(c fiber.Ctx) bool


Import the middleware package that is part of the Fiber web framework

import (

After you initiate your Fiber app, you can use the following possibilities:

// Initialize default config

// Or extend your config for customization
Error: fiber.ErrTooEarly,
// ...


Nextfunc(fiber.Ctx) boolNext defines a function to skip this middleware when returned true.nil
IsEarlyDatafunc(fiber.Ctx) boolIsEarlyData returns whether the request is an early-data request.Function checking if "Early-Data" header equals "1"
AllowEarlyDatafunc(fiber.Ctx) boolAllowEarlyData returns whether the early-data request should be allowed or rejected.Function rejecting on unsafe and allowing safe methods
ErrorerrorError is returned in case an early-data request is rejected.fiber.ErrTooEarly

Default Config

var ConfigDefault = Config{
IsEarlyData: func(c fiber.Ctx) bool {
return c.Get(DefaultHeaderName) == DefaultHeaderTrueValue
AllowEarlyData: func(c fiber.Ctx) bool {
return fiber.IsMethodSafe(c.Method())
Error: fiber.ErrTooEarly,


const (
DefaultHeaderName = "Early-Data"
DefaultHeaderTrueValue = "1"