diff --git a/lib/error_tracker.ex b/lib/error_tracker.ex
index c737cde..ea9b643 100644
--- a/lib/error_tracker.ex
+++ b/lib/error_tracker.ex
@@ -67,6 +67,11 @@ defmodule ErrorTracker do
   """
   @type context :: %{String.t() => any()}
 
+  @typedoc """
+  An `Exception` or a `{kind, payload}` tuple compatible with `Exception.normalize/3`.
+  """
+  @type exception :: Exception.t() | {:error, any()} | {Exception.non_error_kind(), any()}
+
   import Ecto.Query
 
   alias ErrorTracker.Error
@@ -107,6 +112,8 @@ defmodule ErrorTracker do
   * A `{kind, exception}` tuple in which case the information is converted to
   an Elixir exception (if possible) and stored.
   """
+
+  @spec report(exception(), Exception.stacktrace(), context()) :: Occurrence.t() | :noop
   def report(exception, stacktrace, given_context \\ %{}) do
     {kind, reason} = normalize_exception(exception, stacktrace)
     {:ok, stacktrace} = ErrorTracker.Stacktrace.new(stacktrace)
@@ -127,6 +134,7 @@ defmodule ErrorTracker do
   If an error is marked as resolved and it happens again, it will automatically
   appear as unresolved again.
   """
+  @spec resolve(Error.t()) :: {:ok, Error.t()} | {:error, Ecto.Changeset.t()}
   def resolve(error = %Error{status: :unresolved}) do
     changeset = Ecto.Changeset.change(error, status: :resolved)
 
@@ -139,6 +147,7 @@ defmodule ErrorTracker do
   @doc """
   Marks an error as unresolved.
   """
+  @spec unresolve(Error.t()) :: {:ok, Error.t()} | {:error, Ecto.Changeset.t()}
   def unresolve(error = %Error{status: :resolved}) do
     changeset = Ecto.Changeset.change(error, status: :unresolved)
 
diff --git a/lib/error_tracker/migration.ex b/lib/error_tracker/migration.ex
index e6fdc19..cc098c8 100644
--- a/lib/error_tracker/migration.ex
+++ b/lib/error_tracker/migration.ex
@@ -96,14 +96,17 @@ defmodule ErrorTracker.Migration do
   @callback down(Keyword.t()) :: :ok
   @callback current_version(Keyword.t()) :: non_neg_integer()
 
+  @spec up(Keyword.t()) :: :ok
   def up(opts \\ []) when is_list(opts) do
     migrator().up(opts)
   end
 
+  @spec down(Keyword.t()) :: :ok
   def down(opts \\ []) when is_list(opts) do
     migrator().down(opts)
   end
 
+  @spec migrated_version(Keyword.t()) :: non_neg_integer()
   def migrated_version(opts \\ []) when is_list(opts) do
     migrator().migrated_version(opts)
   end
diff --git a/lib/error_tracker/schemas/error.ex b/lib/error_tracker/schemas/error.ex
index 2c4ab45..a31bfee 100644
--- a/lib/error_tracker/schemas/error.ex
+++ b/lib/error_tracker/schemas/error.ex
@@ -12,6 +12,8 @@ defmodule ErrorTracker.Error do
 
   use Ecto.Schema
 
+  @type t :: %__MODULE__{}
+
   schema "error_tracker_errors" do
     field :kind, :string
     field :reason, :string
diff --git a/lib/error_tracker/schemas/occurrence.ex b/lib/error_tracker/schemas/occurrence.ex
index 4729e2e..8cf0b5c 100644
--- a/lib/error_tracker/schemas/occurrence.ex
+++ b/lib/error_tracker/schemas/occurrence.ex
@@ -6,10 +6,13 @@ defmodule ErrorTracker.Occurrence do
   in which the exception raised.
   """
 
+  import Ecto.Changeset
+
   use Ecto.Schema
 
   require Logger
-  import Ecto.Changeset
+
+  @type t :: %__MODULE__{}
 
   schema "error_tracker_occurrences" do
     field :context, :map
diff --git a/lib/error_tracker/schemas/stacktrace.ex b/lib/error_tracker/schemas/stacktrace.ex
index cf22f31..24e8bb0 100644
--- a/lib/error_tracker/schemas/stacktrace.ex
+++ b/lib/error_tracker/schemas/stacktrace.ex
@@ -6,6 +6,8 @@ defmodule ErrorTracker.Stacktrace do
 
   use Ecto.Schema
 
+  @type t :: %__MODULE__{}
+
   @primary_key false
   embedded_schema do
     embeds_many :lines, Line, primary_key: false do