diff --git a/lib/kindling/client.ex b/lib/kindling/client.ex
index d590bad..661a198 100644
--- a/lib/kindling/client.ex
+++ b/lib/kindling/client.ex
@@ -49,7 +49,10 @@ defmodule Kindling.Client do
     |> req_fn.(headers: headers)
     |> case do
       {:ok, %{status: status} = response} when status >= 200 and status < 300 ->
-        Converter.convert(resource_module.version_namespace(), response.body)
+        {:ok, Converter.convert(resource_module.version_namespace(), response.body)}
+
+      {:ok, %{body: %{"resourceType" => _}} = response} ->
+        {:error, Converter.convert(resource_module.version_namespace(), response.body)}
 
       other ->
         other
@@ -86,13 +89,86 @@ defmodule Kindling.Client do
     |> req_fn.(headers: headers)
     |> case do
       {:ok, %{status: status} = response} when status >= 200 and status < 300 ->
-        Converter.convert(resource_module.version_namespace(), response.body)
+        {:ok, Converter.convert(resource_module.version_namespace(), response.body)}
+
+      {:ok, %{body: %{"resourceType" => _}} = response} ->
+        {:error, Converter.convert(resource_module.version_namespace(), response.body)}
 
       other ->
         other
     end
   end
 
+  def create(client, resource_module, attrs, opts \\ [], req_fn \\ &Kindling.Client.Req.post/2) do
+    base_uri = URI.parse(client.base_url)
+    uri = base_uri |> URI.append_path(resource_module.path())
+    more_headers = Keyword.get(opts, :headers, [])
+
+    headers = headers(client, more_headers)
+
+    uri
+    |> req_fn.(headers: headers, json: attrs)
+    |> case do
+      {:ok, %{status: status} = response} when status >= 200 and status < 300 ->
+        {:ok, Converter.convert(resource_module.version_namespace(), response.body)}
+
+      {:ok, %{body: %{"resourceType" => _}} = response} ->
+        {:error, Converter.convert(resource_module.version_namespace(), response.body)}
+
+      other ->
+        other
+    end
+  end
+
+  def update(client, resource_module, id, attrs, opts \\ [], req_fn \\ &Kindling.Client.Req.put/2) do
+    base_uri = URI.parse(client.base_url)
+    uri = base_uri |> URI.append_path(resource_module.path()) |> URI.append_path("/#{id}")
+    more_headers = Keyword.get(opts, :headers, [])
+
+    headers = headers(client, more_headers)
+
+    uri
+    |> req_fn.(headers: headers, json: attrs)
+    |> case do
+      {:ok, %{status: status} = response} when status >= 200 and status < 300 ->
+        {:ok, Converter.convert(resource_module.version_namespace(), response.body)}
+
+      {:ok, %{body: %{"resourceType" => _}} = response} ->
+        {:error, Converter.convert(resource_module.version_namespace(), response.body)}
+
+      other ->
+        other
+    end
+  end
+
+  def delete(client, resource_module, id, opts \\ [], req_fn \\ &Kindling.Client.Req.delete/2) do
+    base_uri = URI.parse(client.base_url)
+    uri = base_uri |> URI.append_path(resource_module.path()) |> URI.append_path("/#{id}")
+    more_headers = Keyword.get(opts, :headers, [])
+
+    headers = headers(client, more_headers)
+
+    uri
+    |> req_fn.(headers: headers)
+    |> convert_response(resource_module)
+  end
+
+  def convert_response({:ok, %{status: status}}, _resource_module)
+      when status == 204 do
+    :ok
+  end
+
+  def convert_response({:ok, %{status: status} = response}, resource_module)
+      when status >= 200 and status < 300 do
+    {:ok, Converter.convert(resource_module.version_namespace(), response.body)}
+  end
+
+  def convert_response({:ok, %{body: %{"resourceType" => _}} = response}, resource_module) do
+    {:error, Converter.convert(resource_module.version_namespace(), response.body)}
+  end
+
+  def convert_response(other, _), do: other
+
   @doc false
   def headers(client, more_headers) do
     case client.auth_mode do
diff --git a/lib/kindling/client/req.ex b/lib/kindling/client/req.ex
index b8f3a26..c88142d 100644
--- a/lib/kindling/client/req.ex
+++ b/lib/kindling/client/req.ex
@@ -2,4 +2,16 @@ defmodule Kindling.Client.Req do
   def get(request, opts \\ []) do
     Req.get(request, opts)
   end
+
+  def post(request, opts \\ []) do
+    Req.post(request, opts)
+  end
+
+  def put(request, opts \\ []) do
+    Req.put(request, opts)
+  end
+
+  def delete(request, opts \\ []) do
+    Req.delete(request, opts)
+  end
 end
diff --git a/lib/kindling/converter.ex b/lib/kindling/converter.ex
index c60fcc8..2e20235 100644
--- a/lib/kindling/converter.ex
+++ b/lib/kindling/converter.ex
@@ -42,11 +42,24 @@ defmodule Kindling.Converter do
 
     atom_map =
       resource_json
-      |> Enum.map(fn {key_string, value} ->
+      |> map_or_nil(fn {key_string, value} ->
         key_atom = key_string |> Recase.to_snake() |> String.to_existing_atom()
-        {key_atom, convert_field(resource_module, resource_list_module, key_atom, value)}
+
+        case value do
+          nil ->
+            {key_atom, nil}
+
+          value ->
+            {key_atom, convert_field(resource_module, resource_list_module, key_atom, value)}
+        end
       end)
-      |> Map.new()
+      |> case do
+        nil ->
+          nil
+
+        enum ->
+          Map.new(enum)
+      end
 
     struct!(resource_module, atom_map)
   end
@@ -85,6 +98,16 @@ defmodule Kindling.Converter do
     end
   end
 
+  defp do_cast_field({:array, _} = type, value) do
+    case Ecto.Type.cast(type, wrap(value)) do
+      {:ok, v} ->
+        v
+
+      other ->
+        other
+    end
+  end
+
   defp do_cast_field(type, value) do
     case Ecto.Type.cast(type, value) do
       {:ok, v} ->
@@ -101,7 +124,7 @@ defmodule Kindling.Converter do
 
     case cardinality do
       :many ->
-        Enum.map(value, &structify(type, resource_list_module, &1))
+        map_or_nil(wrap(value), &structify(type, resource_list_module, &1))
 
       :one ->
         structify(type, resource_list_module, value)
@@ -114,10 +137,20 @@ defmodule Kindling.Converter do
 
     case cardinality do
       :many ->
-        Enum.map(value, &structify(type, resource_list_module, &1))
+        map_or_nil(wrap(value), &structify(type, resource_list_module, &1))
 
       :one ->
         structify(type, resource_list_module, value)
     end
   end
+
+  defp map_or_nil(nil, _), do: nil
+
+  defp map_or_nil(enum, mapper) do
+    Enum.map(enum, mapper)
+  end
+
+  defp wrap(binary) when is_binary(binary), do: [binary]
+  defp wrap(list) when is_list(list), do: list
+  defp wrap(other), do: [other]
 end
diff --git a/lib/kindling/converter/date_time.ex b/lib/kindling/converter/date_time.ex
index b63be3a..5f3e9ae 100644
--- a/lib/kindling/converter/date_time.ex
+++ b/lib/kindling/converter/date_time.ex
@@ -13,6 +13,12 @@ defmodule Kindling.Converter.DateTime do
             second: "",
             zone: ""
 
+  def parse!(value) do
+    {:ok, v, 0} = parse(value)
+
+    v
+  end
+
   @doc """
   Parse a string containing a FHIR-style datetime. Return `{:ok, DateTime.t(), integer()}` or a parse
   error.
diff --git a/lib/kindling/embed_template.eex b/lib/kindling/embed_template.eex
index fec282c..0c65d20 100644
--- a/lib/kindling/embed_template.eex
+++ b/lib/kindling/embed_template.eex
@@ -38,13 +38,17 @@ defmodule <%= @namespace %>.<%= @version %>.<%= class_name(@resource_name) %> do
   def version_namespace, do: <%= @namespace %>.<%= @version %>
   def version, do: "<%= @version %>"
 
-  def base_changeset(data \\ %__MODULE__{}, attrs) do
+  def changeset(data \\ %__MODULE__{}, attrs) do
     data
     |> cast(attrs, @fields)
     <%= for {name, df, _} <- @properties.has_one do %>|> cast_assoc(:<%= Recase.to_snake(name) %>, with: &<%= @namespace %>.<%= @version %>.<%= ref_to_class_name(df["$ref"]) %>.base_changeset/1)
     <% end %>
     <%= for {name, df, _} <- @properties.has_many do %>|> cast_assoc(:<%= Recase.to_snake(name) %>, with: &<%= @namespace %>.<%= @version %>.<%= ref_to_class_name(df["items"]["$ref"]) %>.base_changeset/1)
     <% end %>
+    <%= for {name, _df, _} <- @properties.embeds_one do %>|> cast_embed(:<%= Recase.to_snake(name) %>)
+    <% end %>
+    <%= for {name, _df, _} <- @properties.embeds_many do %>|> cast_embed(:<%= Recase.to_snake(name) %>)
+    <% end %>
     |> validate_required(@required_fields)
   end
 end
diff --git a/lib/kindling/template.eex b/lib/kindling/template.eex
index 6255953..d713f6f 100644
--- a/lib/kindling/template.eex
+++ b/lib/kindling/template.eex
@@ -43,13 +43,17 @@ defmodule <%= @namespace %>.<%= @version %>.<%= class_name(@resource_name) %> do
   def version, do: "<%= @version %>"
   def path, do: "/<%= @resource_name %>"
 
-  def base_changeset(data \\ %__MODULE__{}, attrs) do
+  def changeset(data \\ %__MODULE__{}, attrs) do
     data
     |> cast(attrs, @fields)
     <%= for {name, df, _} <- @properties.has_one do %>|> cast_assoc(:<%= Recase.to_snake(name) %>, with: &<%= @namespace %>.<%= @version %>.<%= ref_to_class_name(df["$ref"]) %>.base_changeset/1)
     <% end %>
     <%= for {name, df, _} <- @properties.has_many do %>|> cast_assoc(:<%= Recase.to_snake(name) %>, with: &<%= @namespace %>.<%= @version %>.<%= ref_to_class_name(df["items"]["$ref"]) %>.base_changeset/1)
     <% end %>
+    <%= for {name, _df, _} <- @properties.embeds_one do %>|> cast_embed(:<%= Recase.to_snake(name) %>)
+    <% end %>
+    <%= for {name, _df, _} <- @properties.embeds_many do %>|> cast_embed(:<%= Recase.to_snake(name) %>)
+    <% end %>
     |> validate_required(@required_fields)
   end
 end
diff --git a/lib/kindling/xml.ex b/lib/kindling/xml.ex
new file mode 100644
index 0000000..1c3ddca
--- /dev/null
+++ b/lib/kindling/xml.ex
@@ -0,0 +1,47 @@
+defmodule Kindling.Xml do
+  def parse(doc) do
+    case Saxy.SimpleForm.parse_string(doc) do
+      {:ok, tree} ->
+        process(tree)
+
+      other ->
+        other
+    end
+  end
+
+  def process({resource_type, _, children}) do
+    base = %{
+      "resourceType" => resource_type
+    }
+
+    Enum.reduce(children, base, &reduce_child/2)
+  end
+
+  def reduce_child(binary, acc) when is_binary(binary), do: acc
+
+  def reduce_child({"div", _subattrs, _children}, acc), do: acc
+
+  def reduce_child({attribute_name, subattrs, children}, acc) do
+    value =
+      case subattrs do
+        [{"value", value}] ->
+          value
+
+        list when is_list(list) ->
+          attrs = Enum.into(list, %{})
+
+          Enum.reduce(children, attrs, &reduce_child/2)
+      end
+
+    case Map.get(acc, attribute_name) do
+      nil ->
+        Map.put(acc, attribute_name, value)
+
+      list when is_list(list) ->
+        Map.put(acc, attribute_name, list ++ [value])
+
+      other ->
+        Map.put(acc, attribute_name, [other, value])
+    end
+  end
+end
diff --git a/mix.exs b/mix.exs
index 2ff3f69..34970a0 100644
--- a/mix.exs
+++ b/mix.exs
@@ -43,11 +43,12 @@ defmodule Kindling.MixProject do
   defp deps do
     [
       {:credo, "~> 1.7", only: [:dev]},
-      {:ecto, "~> 3.11", only: [:dev, :test]},
+      {:ecto, "~> 3.11"},
       {:ex_doc, "~> 0.31.2", only: [:dev]},
       {:jason, "~> 1.4"},
       {:recase, "~> 0.7.0"},
-      {:req, "~> 0.4.11"}
+      {:req, "~> 0.4.11"},
+      {:saxy, "~> 1.5.0"}
       # {:dep_from_hexpm, "~> 0.3.0"},
       # {:dep_from_git, git: "https://github.com/elixir-lang/my_dep.git", tag: "0.1.0"}
     ]
diff --git a/mix.lock b/mix.lock
index 399365f..2d5d8bd 100644
--- a/mix.lock
+++ b/mix.lock
@@ -21,5 +21,6 @@
   "nimble_pool": {:hex, :nimble_pool, "1.0.0", "5eb82705d138f4dd4423f69ceb19ac667b3b492ae570c9f5c900bb3d2f50a847", [:mix], [], "hexpm", "80be3b882d2d351882256087078e1b1952a28bf98d0a287be87e4a24a710b67a"},
   "recase": {:hex, :recase, "0.7.0", "3f2f719f0886c7a3b7fe469058ec539cb7bbe0023604ae3bce920e186305e5ae", [:mix], [], "hexpm", "36f5756a9f552f4a94b54a695870e32f4e72d5fad9c25e61bc4a3151c08a4e0c"},
   "req": {:hex, :req, "0.4.11", "cb19f87d5251e7de30cfc67d1899696b290711092207c6b2e8fc2294f237fcdc", [:mix], [{:aws_signature, "~> 0.3.2", [hex: :aws_signature, repo: "hexpm", optional: true]}, {:brotli, "~> 0.3.1", [hex: :brotli, repo: "hexpm", optional: true]}, {:ezstd, "~> 1.0", [hex: :ezstd, repo: "hexpm", optional: true]}, {:finch, "~> 0.17", [hex: :finch, repo: "hexpm", optional: false]}, {:jason, "~> 1.0", [hex: :jason, repo: "hexpm", optional: false]}, {:mime, "~> 1.6 or ~> 2.0", [hex: :mime, repo: "hexpm", optional: false]}, {:nimble_csv, "~> 1.0", [hex: :nimble_csv, repo: "hexpm", optional: true]}, {:nimble_ownership, "~> 0.2.0", [hex: :nimble_ownership, repo: "hexpm", optional: false]}, {:plug, "~> 1.0", [hex: :plug, repo: "hexpm", optional: true]}], "hexpm", "bbf4f2393c649fa4146a3b8470e2a7e8c9b23e4100a16c75f5e7d1d3d33144f3"},
+  "saxy": {:hex, :saxy, "1.5.0", "0141127f2d042856f135fb2d94e0beecda7a2306f47546dbc6411fc5b07e28bf", [:mix], [], "hexpm", "ea7bb6328fbd1f2aceffa3ec6090bfb18c85aadf0f8e5030905e84235861cf89"},
   "telemetry": {:hex, :telemetry, "1.2.1", "68fdfe8d8f05a8428483a97d7aab2f268aaff24b49e0f599faa091f1d4e7f61c", [:rebar3], [], "hexpm", "dad9ce9d8effc621708f99eac538ef1cbe05d6a874dd741de2e689c47feafed5"},
 }
diff --git a/test/kindling_test.exs b/test/kindling_test.exs
index 3d92d45..5ac2310 100644
--- a/test/kindling_test.exs
+++ b/test/kindling_test.exs
@@ -1,8 +1,4 @@
 defmodule KindlingTest do
   use ExUnit.Case
   doctest Kindling
-
-  test "greets the world" do
-    assert Kindling.hello() == :world
-  end
 end