diff --git a/Gemfile b/Gemfile
index 47534f7..2eeafcf 100644
--- a/Gemfile
+++ b/Gemfile
@@ -85,6 +85,9 @@ gem "faraday", "~> 2.13"
 
 gem "oauth2", "~> 2.0"
 
+gem "omniauth", "~> 2.1"
+gem "omniauth_openid_connect", "~> 0.7"
+
 gem "snail", "~> 2.3"
 
 gem "easypost", "~> 7.1"
diff --git a/Gemfile.lock b/Gemfile.lock
index 728a4c8..14f06d6 100644
--- a/Gemfile.lock
+++ b/Gemfile.lock
@@ -94,6 +94,7 @@ GEM
       kaminari (>= 1.0)
       sassc-rails (~> 2.1)
       selectize-rails (~> 0.6)
+    aes_key_wrap (1.1.0)
     andand (1.3.3)
     annotaterb (4.16.0)
       activerecord (>= 6.0.0)
@@ -101,6 +102,7 @@ GEM
     argon2-kdf (0.3.1)
       fiddle
     ast (2.4.3)
+    attr_required (1.0.2)
     awesome_print (1.9.2)
     aws-eventstream (1.4.0)
     aws-partitions (1.1124.0)
@@ -126,6 +128,7 @@ GEM
     bcrypt_pbkdf (1.1.1-x86_64-darwin)
     benchmark (0.4.1)
     bigdecimal (3.2.2)
+    bindata (2.5.1)
     bindex (0.8.1)
     blazer (3.3.0)
       activerecord (>= 7.1)
@@ -175,6 +178,8 @@ GEM
     dry-cli (1.2.0)
     easypost (7.1.0)
     ed25519 (1.4.0)
+    email_validator (2.2.4)
+      activemodel
     erb (5.0.1)
     erubi (1.13.1)
     et-orbi (1.2.11)
@@ -184,6 +189,8 @@ GEM
       faraday-net_http (>= 2.0, < 3.5)
       json
       logger
+    faraday-follow_redirects (0.4.0)
+      faraday (>= 1, < 3)
     faraday-multipart (1.1.0)
       multipart-post (~> 2.0)
     faraday-net_http (3.4.1)
@@ -261,6 +268,13 @@ GEM
       railties (>= 4.2.0)
       thor (>= 0.14, < 2.0)
     json (2.12.2)
+    json-jwt (1.17.0)
+      activesupport (>= 4.2)
+      aes_key_wrap
+      base64
+      bindata
+      faraday (~> 2.0)
+      faraday-follow_redirects
     jwt (3.1.1)
       base64
     kamal (2.6.1)
@@ -372,6 +386,27 @@ GEM
       snaky_hash (~> 2.0, >= 2.0.3)
       version_gem (>= 1.1.8, < 3)
     observer (0.1.2)
+    omniauth (2.1.4)
+      hashie (>= 3.4.6)
+      logger
+      rack (>= 2.2.3)
+      rack-protection
+    omniauth_openid_connect (0.8.0)
+      omniauth (>= 1.9, < 3)
+      openid_connect (~> 2.2)
+    openid_connect (2.3.1)
+      activemodel
+      attr_required (>= 1.0.0)
+      email_validator
+      faraday (~> 2.0)
+      faraday-follow_redirects
+      json-jwt (>= 1.16)
+      mail
+      rack-oauth2 (~> 2.2)
+      swd (~> 2.0)
+      tzinfo
+      validate_url
+      webfinger (~> 2.0)
     ostruct (0.6.1)
     parallel (1.27.0)
     parser (3.3.8.0)
@@ -413,6 +448,17 @@ GEM
     raabro (1.4.0)
     racc (1.8.1)
     rack (3.1.16)
+    rack-oauth2 (2.3.0)
+      activesupport
+      attr_required
+      faraday (~> 2.0)
+      faraday-follow_redirects
+      json-jwt (>= 1.11.0)
+      rack (>= 2.1.0)
+    rack-protection (4.2.1)
+      base64 (>= 0.1.0)
+      logger (>= 1.6.0)
+      rack (>= 3.0.0, < 4)
     rack-proxy (0.7.7)
       rack
     rack-session (2.1.1)
@@ -571,6 +617,11 @@ GEM
     stimulus-rails (1.3.4)
       railties (>= 6.0.0)
     stringio (3.1.7)
+    swd (2.0.3)
+      activesupport (>= 3)
+      attr_required (>= 0.0.5)
+      faraday (~> 2.0)
+      faraday-follow_redirects
     temple (0.10.3)
     thor (1.3.2)
     thruster (0.1.14)
@@ -597,6 +648,9 @@ GEM
     valid_email2 (7.0.13)
       activemodel (>= 6.0)
       mail (~> 2.5)
+    validate_url (1.0.15)
+      activemodel (>= 3.0.0)
+      public_suffix
     version_gem (1.1.8)
     vite_rails (3.0.19)
       railties (>= 5.1, < 9)
@@ -612,6 +666,10 @@ GEM
       activemodel (>= 6.0.0)
       bindex (>= 0.4.0)
       railties (>= 6.0.0)
+    webfinger (2.1.3)
+      activesupport
+      faraday (~> 2.0)
+      faraday-follow_redirects
     webrick (1.9.1)
     websocket (1.2.11)
     websocket-driver (0.7.7)
@@ -676,6 +734,8 @@ DEPENDENCIES
   nokogiri (~> 1.18)
   norairrecord (~> 0.4.0)
   oauth2 (~> 2.0)
+  omniauth (~> 2.1)
+  omniauth_openid_connect (~> 0.7)
   parallel (~> 1.26)
   pg (~> 1.1)
   phlex-pdf (~> 0.1.2)
diff --git a/app/controllers/sessions_controller.rb b/app/controllers/sessions_controller.rb
index 3211f56..97c6b1b 100644
--- a/app/controllers/sessions_controller.rb
+++ b/app/controllers/sessions_controller.rb
@@ -1,45 +1,8 @@
 class SessionsController < ApplicationController
-  skip_before_action :authenticate_user!, only: [:new, :create]
+  skip_before_action :authenticate_user!, only: [:omniauth_failure, :hackclub_callback]
 
   skip_after_action :verify_authorized
 
-  def new
-    redirect_uri = url_for(action: :create, only_path: false)
-    Rails.logger.info "Starting Slack OAuth flow with redirect URI: #{redirect_uri}"
-    redirect_to User.authorize_url(redirect_uri),
-                host: "https://slack.com",
-                allow_other_host: true
-  end
-
-  def create
-    redirect_uri = url_for(action: :create, only_path: false)
-
-    if params[:error].present?
-      Rails.logger.error "Slack OAuth error: #{params[:error]}"
-      uuid = Honeybadger.notify("Slack OAuth error: #{params[:error]}")
-      redirect_to login_path, alert: "failed to authenticate with Slack! (error: #{uuid})"
-      return
-    end
-
-    begin
-      @user = User.from_slack_token(params[:code], redirect_uri)
-    rescue => e
-      Rails.logger.error "Error creating user from Slack data: #{e.message}"
-      uuid = Honeybadger.notify(e)
-      redirect_to login_path, alert: "error authenticating! (error: #{uuid})"
-      return
-    end
-
-    if @user&.persisted?
-      session[:user_id] = @user.id
-      flash[:success] = "welcome aboard!"
-      redirect_to root_path
-    else
-      Rails.logger.error "Failed to create/update user from Slack data"
-      redirect_to login_path, alert: "are you sure you should be here?"
-    end
-  end
-
   def impersonate
     unless current_user.admin?
       redirect_to root_path, alert: "you are not authorized to impersonate users. this incident has been reported :-P"
@@ -64,4 +27,35 @@ class SessionsController < ApplicationController
     session[:user_id] = nil
     redirect_to root_path, notice: "bye, see you next time!"
   end
+
+  def omniauth_failure
+    redirect_to login_path, alert: "Authentication failed: #{params[:message]}"
+  end
+
+  def hackclub_callback
+    auth = request.env["omniauth.auth"]
+
+    if auth.nil?
+      redirect_to login_path, alert: "Authentication failed"
+      return
+    end
+
+    begin
+      @user = User.from_hack_club_auth(auth)
+    rescue => e
+      Rails.logger.error "Error creating user from Hack Club Auth: #{e.message}"
+      uuid = Honeybadger.notify(e)
+      redirect_to login_path, alert: "error authenticating! (error: #{uuid})"
+      return
+    end
+
+    if @user&.persisted?
+      session[:user_id] = @user.id
+      flash[:success] = "welcome aboard!"
+      redirect_to root_path
+    else
+      Rails.logger.error "Failed to create/update user from Hack Club Auth"
+      redirect_to login_path, alert: "are you sure you should be here?"
+    end
+  end
 end
diff --git a/app/dashboards/user_dashboard.rb b/app/dashboards/user_dashboard.rb
index 90586d1..2569c27 100644
--- a/app/dashboards/user_dashboard.rb
+++ b/app/dashboards/user_dashboard.rb
@@ -14,6 +14,7 @@ class UserDashboard < Administrate::BaseDashboard
     icon_url: Field::String,
     is_admin: Field::Boolean,
     slack_id: Field::String,
+    hca_id: Field::String,
     username: Field::String,
     warehouse_templates: Field::HasMany,
     home_mid: Field::BelongsTo,
@@ -32,7 +33,7 @@ class UserDashboard < Administrate::BaseDashboard
     is_admin
     can_warehouse
     email
-    slack_id
+    hca_id
   ].freeze
 
   # SHOW_PAGE_ATTRIBUTES
@@ -44,6 +45,7 @@ class UserDashboard < Administrate::BaseDashboard
     icon_url
     is_admin
     slack_id
+    hca_id
     username
     warehouse_templates
     home_mid
@@ -61,6 +63,7 @@ class UserDashboard < Administrate::BaseDashboard
     icon_url
     is_admin
     slack_id
+    hca_id
     username
     home_mid
     home_return_address
diff --git a/app/models/user.rb b/app/models/user.rb
index b56de90..23cbca6 100644
--- a/app/models/user.rb
+++ b/app/models/user.rb
@@ -14,6 +14,7 @@
 #  updated_at             :datetime         not null
 #  home_mid_id            :bigint           default(1), not null
 #  home_return_address_id :bigint           default(1), not null
+#  hca_id                 :string
 #  slack_id               :string
 #
 # Indexes
@@ -45,46 +46,30 @@ class User < ApplicationRecord
 
   def remove_admin! = update!(is_admin: false)
 
-  def self.authorize_url(redirect_uri)
-    params = {
-      client_id: ENV["SLACK_CLIENT_ID"],
-      redirect_uri: redirect_uri,
-      state: SecureRandom.hex(24),
-      user_scope: "users.profile:read,users:read,users:read.email",
-    }
+  def self.from_hack_club_auth(auth_hash)
+    hca_id = auth_hash.dig("uid")
+    return nil unless hca_id
 
-    URI.parse("https://slack.com/oauth/v2/authorize?#{params.to_query}")
-  end
+    # Try to find by hca_id first
+    user = find_by(hca_id: hca_id)
 
-  def self.from_slack_token(code, redirect_uri)
-    # Exchange code for token
-    response = HTTP.post("https://slack.com/api/oauth.v2.access", form: {
-                                                                    client_id: ENV["SLACK_CLIENT_ID"],
-                                                                    client_secret: ENV["SLACK_CLIENT_SECRET"],
-                                                                    code: code,
-                                                                    redirect_uri: redirect_uri,
-                                                                  })
+    # If not found, try to migrate from slack_id
+    unless user
+      slack_id = auth_hash.dig("extra", "raw_info", "slack_id")
+      if slack_id.present?
+        user = find_by(slack_id: slack_id)
+        if user
+          # Migrate user to use hca_id
+          user.hca_id = hca_id
+        end
+      end
+    end
 
-    data = JSON.parse(response.body.to_s)
-
-    return nil unless data["ok"]
-
-    # Get user info
-    user_response = HTTP.auth("Bearer #{data["authed_user"]["access_token"]}")
-                        .get("https://slack.com/api/users.info?user=#{data["authed_user"]["id"]}")
-
-    user_data = JSON.parse(user_response.body.to_s)
-
-    return nil unless user_data["ok"]
-
-    user = find_by(slack_id: data.dig("authed_user", "id"))
     return nil unless user
 
-    user.email = user_data.dig("user", "profile", "email")
-    user.username ||= user_data.dig("user", "profile", "username")
-    user.username ||= user_data.dig("user", "profile", "display_name_normalized")
-    user.icon_url = user_data.dig("user", "profile", "image_192") || user_data.dig("user", "profile", "image_72")
-    # Store the OAuth data
+    user.email = auth_hash.dig("info", "email")
+    user.username ||= auth_hash.dig("info", "name")
+
     user.save!
     user
   end
diff --git a/app/views/static_pages/login.html.erb b/app/views/static_pages/login.html.erb
index 9bb81a0..ee834a6 100644
--- a/app/views/static_pages/login.html.erb
+++ b/app/views/static_pages/login.html.erb
@@ -8,6 +8,9 @@
 <%= vite_image_tag 'images/login/treasure.png', id: "treasure" %>
 <%= render 'shared/flash' %>
 <h1>welcome ashore...</h1>
-<%= link_to "log in?", slack_auth_path %>
+<form action="/back_office/auth/hackclub" method="post">
+  <input type="hidden" name="authenticity_token" value="<%= form_authenticity_token %>">
+  <button type="submit">log in with hack club?</button>
+</form>
 </body>
 </html>
diff --git a/config/initializers/hack_club_auth.rb b/config/initializers/hack_club_auth.rb
new file mode 100644
index 0000000..e1d2c9c
--- /dev/null
+++ b/config/initializers/hack_club_auth.rb
@@ -0,0 +1,8 @@
+# frozen_string_literal: true
+
+Rails.application.config.hack_club_auth = ActiveSupport::OrderedOptions.new
+Rails.application.config.hack_club_auth.client_id = ENV.fetch("HACKCLUB_CLIENT_ID", nil)
+Rails.application.config.hack_club_auth.client_secret = ENV.fetch("HACKCLUB_CLIENT_SECRET", nil)
+Rails.application.config.hack_club_auth.base_url = ENV.fetch("HACKCLUB_AUTH_URL") do
+  Rails.env.production? ? "https://auth.hackclub.com" : "https://hca.dinosaurbbq.org"
+end
diff --git a/config/initializers/omniauth.rb b/config/initializers/omniauth.rb
new file mode 100644
index 0000000..179fb77
--- /dev/null
+++ b/config/initializers/omniauth.rb
@@ -0,0 +1,18 @@
+# frozen_string_literal: true
+
+Rails.application.config.middleware.use OmniAuth::Builder do
+  provider :openid_connect,
+    name: :hackclub,
+    issuer: Rails.application.config.hack_club_auth.base_url,
+    discovery: true,
+    client_options: {
+      identifier: Rails.application.config.hack_club_auth.client_id,
+      secret: Rails.application.config.hack_club_auth.client_secret,
+      redirect_uri: ->(env) { "#{env['rack.url_scheme']}://#{env['HTTP_HOST']}/back_office/auth/hackclub/callback" }
+    },
+    scope: %i[openid profile email slack_id]
+end
+
+OmniAuth.config.path_prefix = "/back_office/auth"
+OmniAuth.config.request_validation_phase = OmniAuth::AuthenticityTokenProtection.new(key: :_csrf_token)
+OmniAuth.config.allowed_request_methods = [:post]
diff --git a/config/locales/en.yml b/config/locales/en.yml
index a986337..4a55cfb 100644
--- a/config/locales/en.yml
+++ b/config/locales/en.yml
@@ -33,6 +33,7 @@ en:
       user:
         home_mid: "Home Mailer ID"
         home_return_address: "Home Return Address"
+        hca_id: Hack Club Auth ID
       usps_payment_account:
         ach: "is ACH?"
   helpers:
diff --git a/config/routes.rb b/config/routes.rb
index d365b6b..fd8dc54 100644
--- a/config/routes.rb
+++ b/config/routes.rb
@@ -559,10 +559,9 @@ Rails.application.routes.draw do
 
     delete "signout", to: "sessions#destroy", as: :signout
     get "/login" => "static_pages#login"
-  end
 
-  get "/auth/slack", to: "sessions#new", as: :slack_auth
-  get "/auth/slack/callback", to: "sessions#create"
+    get "/auth/hackclub/callback", to: "sessions#hackclub_callback", as: :hackclub_callback
+  end
 
   root "public/static_pages#root", as: :public_root
 
diff --git a/db/migrate/20251211000001_add_hca_id_to_users.rb b/db/migrate/20251211000001_add_hca_id_to_users.rb
new file mode 100644
index 0000000..06d5c57
--- /dev/null
+++ b/db/migrate/20251211000001_add_hca_id_to_users.rb
@@ -0,0 +1,6 @@
+class AddHcaIdToUsers < ActiveRecord::Migration[8.0]
+  def change
+    add_column :users, :hca_id, :string
+    add_index :users, :hca_id, unique: true
+  end
+end
diff --git a/db/schema.rb b/db/schema.rb
index 8106c2e..6a059c0 100644
--- a/db/schema.rb
+++ b/db/schema.rb
@@ -10,7 +10,7 @@
 #
 # It's strongly recommended that you check this file into your version control system.
 
-ActiveRecord::Schema[8.0].define(version: 2025_07_29_204357) do
+ActiveRecord::Schema[8.0].define(version: 2025_12_11_000001) do
   # These are extensions that must be enabled in order to support this database
   enable_extension "citext"
   enable_extension "pg_catalog.plpgsql"
@@ -373,6 +373,8 @@ ActiveRecord::Schema[8.0].define(version: 2025_07_29_204357) do
     t.datetime "created_at", null: false
     t.datetime "updated_at", null: false
     t.boolean "opted_out_of_map", default: false
+    t.string "hca_id"
+    t.index ["hca_id"], name: "index_public_users_on_hca_id", unique: true
   end
 
   create_table "return_addresses", force: :cascade do |t|
@@ -411,6 +413,8 @@ ActiveRecord::Schema[8.0].define(version: 2025_07_29_204357) do
     t.boolean "can_impersonate_public"
     t.bigint "home_mid_id", default: 1, null: false
     t.bigint "home_return_address_id", default: 1, null: false
+    t.string "hca_id"
+    t.index ["hca_id"], name: "index_users_on_hca_id", unique: true
     t.index ["home_mid_id"], name: "index_users_on_home_mid_id"
     t.index ["home_return_address_id"], name: "index_users_on_home_return_address_id"
   end