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FusionAuth Go Client semver 2.0.0 compliant Documentation

Use this client to access the FusionAuth APIs in your Go application. For additional information and documentation on FusionAuth refer to


  • @medhir Thank you for the initial commit and initial implementation of the Go client!
  • @markschmid Thank you for your PRs, feedback and suggestions!
  • @MCBrandenburg Thank you for the feedback and PRs!
  • @matthewhartstonge Thank you for the PR!
  • The FusionAuth team - couldn't have done it without you!


go get

Example Usage

The following example uses the FusionAuth Go client to create a request handling function that logs in a user:

package example

import (

const host = "http://localhost:9011"

var httpClient = &http.Client{
	Timeout: time.Second * 10,

var baseURL, _ = url.Parse(host)

// Construct a new FusionAuth Client
var auth = fusionauth.NewClient(httpClient, baseURL, apiKey)

// Login logs in the user using the FusionAuth Go client library
func Login() http.HandlerFunc {
    return http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
        // Read response body
        var credentials fusionauth.LoginRequest
        defer r.Body.Close()
        // Use FusionAuth Go client to log in the user
        authResponse, errors, err := auth.Login(credentials)
        if err != nil {
            http.Error(w, err.Error(), http.StatusBadRequest)
        // Write the response from the FusionAuth client as JSON
        var responseJSON []byte
        if errors != nil {
            responseJSON, err = json.Marshal(errors)
        } else {
            responseJSON, err = json.Marshal(authResponse)
        if err != nil {
            http.Error(w, err.Error(), http.StatusInternalServerError)
        w.Header().Set("Content-Type", "application/json")

You can also call the API directly without logging a user in. This code uses an API key to determine the number of tenants in a FusionAuth installation.

package main

import (

const host = "http://localhost:9011"

var apiKey = "API KEY"
var httpClient = &http.Client{
    Timeout: time.Second * 10,

func main() {
    var baseURL, _ = url.Parse(host)

    // Construct a new FusionAuth Client
    var client = fusionauth.NewClient(httpClient, baseURL, apiKey)
    // for production code, don't ignore the error!
    tenantResponse, _ := client.RetrieveTenants()

Testing source builds

If you are modifying the go client and want to test it locally, follow these steps:

go to directory where you have go code checked out.

mkdir test2
cd test2
go mod init
go mod tidy
vi test.go # put in your test code, in the main package

Then edit go.mod and add these lines at the bottom:

require ( v1.0.0

replace ( v1.0.0 => ../go-client

Then you can run it: go run test.go # or go build

HT for these.

Questions and support

If you have a question or support issue regarding this client library, we'd love to hear from you.

If you have a paid edition with support included, please open a ticket in your account portal. Learn more about paid editions here.

Otherwise, please post your question in the community forum.


Bug reports and pull requests are welcome on GitHub at

If you find an issue with syntax, etc - this is likely a bug in the template. Feel free to submit a PR against the Client Builder project.


The code is available as open source under the terms of the Apache v2.0 License.