diff --git a/CHANGELOG.md b/CHANGELOG.md
index ec3e3be..1203c0d 100644
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -1,8 +1,70 @@
 ## [Unreleased]
 
+## [0.3.0] - 2024-01-04
+
+- **Adds additional flexibility to `Nummy::Enum.to_attribute` (#2)
+
+  This release teaches a few new tricks to `Nummy::Enum.to_attribute`:
+
+  - it allows passing a block to fully customize how keys are transformed
+
+  - it looks for `String#underscore` rather than calling into  `ActiveSupport::Inflector.underscore` directly, which means that users can bring their own monkey patch if they want to.
+
+  - it falls back to `Symbol#downcase` if `String#underscore` is not available. If the constants are defined using `SCREAMING_SNAKE_CASE`, this will generally have the same result as calling `String#underscore`, but without requiring ActiveSupport.
+
+  ```ruby
+  class ShippingStatus < Nummy::Enum
+    IN_TRANSIT = auto
+    OUT_FOR_DELIVERY = auto
+    DELIVERED = auto
+  end
+  ```
+
+  ```ruby
+  # Without ActiveSupport
+  
+  ShippingStatus.to_attribute
+  # v0.2.0 (❌)
+  # => nummy/lib/nummy/enum.rb:379:in `block in to_attribute': uninitialized constant ActiveSupport (NameError)
+  # 
+  #              ::ActiveSupport::Inflector.underscore(key).to_sym
+  #              ^^^^^^^^^^^^^^^
+
+  # v0.3.0 (✅)
+  # => {:in_transit=>0, :out_for_delivery=>1, :delivered=>2}
+  ```
+
+  ```ruby
+  # With ActiveSupport
+  require "active_support/core_ext/string/inflections"
+
+  ShippingStatus.to_attribute
+  # => {:in_transit=>0, :out_for_delivery=>1, :delivered=>2}
+
+  ShippingStatus.to_attribute { |key| key.to_s.underscore.camelize.to_sym }
+  # => {:InTransit=>0, :OutForDelivery=>1, :Delivered=>2}
+  ```
+
+- **Adds JSON serialization support (#3)**
+
+  This release adds two methods to `Nummy::Enum`: `.as_json` and `.to_json`. These methods allow you to serialize an enum to JSON.
+
+  ```ruby
+  class Status < Nummy::Enum
+    ACTIVE = auto
+    ARCHIVED = auto
+  end
+
+  Status.as_json
+  # => {"ACTIVE" => 0, "ARCHIVED" => 1}
+
+  Status.to_json
+  # => "{\"ACTIVE\":0,\"ARCHIVED\":1}
+  ```
+
 ## [0.2.0] - 2024-01-04
 
-- Add `Nummy::Enum.to_attribute`, which converts the enum to a hash that can be passed as the values of an `ActiveRecord::Enum`:
+- Add `Nummy::Enum.to_attribute` (#1), which converts the enum to a hash that can be passed as the values of an `ActiveRecord::Enum`:
   
   ```ruby
   class Conversation < ActiveRecord::Base
diff --git a/lib/nummy/version.rb b/lib/nummy/version.rb
index a32982c..a454d84 100644
--- a/lib/nummy/version.rb
+++ b/lib/nummy/version.rb
@@ -2,5 +2,5 @@
 
 module Nummy
   # The current version of the gem.
-  VERSION = "0.2.0"
+  VERSION = "0.3.0"
 end