diff --git a/README.md b/README.md
index 96370d696..317aa19ab 100644
--- a/README.md
+++ b/README.md
@@ -126,10 +126,10 @@ The Anatomy of Action Class
 # every action needs to inherit from Dynflow::Action
 class Action < Dynflow::Action
 
-  # OPTIONAL: the input format for the execution phase of this action
-  # (https://github.com/iNecas/apipie-params for more details.
-  # Validations can be performed against this description (turned off
-  # for now)
+  # OPTIONAL: the input format for the execution phase of this action.
+  # This is purely documentation - the block is never evaluated and
+  # serves only as a reference for developers implementing actions.
+  # Input validation is not performed.
   input_format do
     param :id, Integer
     param :name, String
diff --git a/doc/pages/source/documentation/index.md b/doc/pages/source/documentation/index.md
index 079ec95a7..e2cfe1968 100644
--- a/doc/pages/source/documentation/index.md
+++ b/doc/pages/source/documentation/index.md
@@ -203,12 +203,12 @@ class AnAction < Dynflow::Action
 end
 ```
 
-This might me quite handy especially in combination with
+This might be quite handy especially in combination with
 [subscriptions](#subscriptions) functionality.
 
-The format follows [apipie-params](https://github.com/iNecas/apipie-params) for more details.
-Validations of input/output could be performed against this description but it's not turned on
-by default. (It needs to be revisited and updated to be fully functional.)
+These format definitions are purely for documentation purposes - the blocks are never
+evaluated and serve only as a reference for developers implementing actions.
+Input/output validation is not performed.
 
 {% endinfo_block %}
 
diff --git a/dynflow.gemspec b/dynflow.gemspec
index 808a9ae4b..c6922d2bf 100644
--- a/dynflow.gemspec
+++ b/dynflow.gemspec
@@ -21,7 +21,6 @@ Gem::Specification.new do |s|
   s.required_ruby_version = '>= 2.7.0'
 
   s.add_dependency "algebrick", '~> 0.7.0'
-  s.add_dependency "apipie-params"
   s.add_dependency "concurrent-ruby", '~> 1.1.3'
   s.add_dependency "concurrent-ruby-edge", '~> 0.6.0'
   s.add_dependency "csv", "~> 3.1"
diff --git a/lib/dynflow.rb b/lib/dynflow.rb
index 312877c82..f5b6c74cf 100644
--- a/lib/dynflow.rb
+++ b/lib/dynflow.rb
@@ -1,6 +1,5 @@
 # frozen_string_literal: true
 
-require 'apipie-params'
 require 'algebrick'
 require 'set'
 require 'base64'
diff --git a/lib/dynflow/action/format.rb b/lib/dynflow/action/format.rb
index bc9369982..373006b47 100644
--- a/lib/dynflow/action/format.rb
+++ b/lib/dynflow/action/format.rb
@@ -1,44 +1,15 @@
 # frozen_string_literal: true
 
 module Dynflow
-  # Input/output format validation logic calling
-  # input_format/output_format with block acts as a setter for
-  # specifying the format. Without a block it acts as a getter
   module Action::Format
-    # we don't evaluate tbe block immediatelly, but postpone it till all the
-    # action classes are loaded, because we can use them to reference output format
     def input_format(&block)
-      case
-      when block && !@input_format_block
-        @input_format_block = block
-      when !block && @input_format_block
-        return @input_format ||= Apipie::Params::Description.define(&@input_format_block)
-      when block && @input_format_block
-        raise "The input_format has already been defined in #{self.class}"
-      when !block && !@input_format_block
-        if superclass.respond_to? :input_format
-          superclass.input_format
-        else
-          raise "The input_format has not been defined yet in #{self.class}"
-        end
-      end
+      # Format definitions are not validated
+      # This method is kept for backward compatibility but does nothing
     end
 
     def output_format(&block)
-      case
-      when block && !@output_format_block
-        @output_format_block = block
-      when !block && @output_format_block
-        return @output_format ||= Apipie::Params::Description.define(&@output_format_block)
-      when block && @output_format_block
-        raise "The output_format has already been defined in #{self.class}"
-      when !block && !@output_format_block
-        if superclass.respond_to? :output_format
-          superclass.output_format
-        else
-          raise "The output_format has not been defined yet in #{self.class}"
-        end
-      end
+      # Format definitions are not validated
+      # This method is kept for backward compatibility but does nothing
     end
   end
 end