diff --git a/validation-form/src/main/scala/tagless/rules.scala b/validation-form/src/main/scala/tagless/rules.scala
index 58da12f7..b76146e1 100644
--- a/validation-form/src/main/scala/tagless/rules.scala
+++ b/validation-form/src/main/scala/tagless/rules.scala
@@ -4,7 +4,7 @@ package forms
 
 import jto.validation.forms._
 
-sealed trait RulesGrammar
+trait RulesGrammar
     extends FormGrammar[Rule]
     with RuleConstraints
     with RulesTypeclasses[PM.PM] {
diff --git a/validation-form/src/main/scala/tagless/writes.scala b/validation-form/src/main/scala/tagless/writes.scala
index f4162f29..9d2828a9 100644
--- a/validation-form/src/main/scala/tagless/writes.scala
+++ b/validation-form/src/main/scala/tagless/writes.scala
@@ -7,7 +7,7 @@ import jto.validation.forms._
 import shapeless.tag.@@
 import types.op
 
-sealed trait WritesGrammar
+trait WritesGrammar
     extends FormGrammar[op[Write]#λ]
     with WriteConstraints
     with WritesTypeclasses[PM.PM] {
diff --git a/validation-jsjson/src/main/scala/tagless/rules.scala b/validation-jsjson/src/main/scala/tagless/rules.scala
index 51f5ba90..0f19ce68 100644
--- a/validation-jsjson/src/main/scala/tagless/rules.scala
+++ b/validation-jsjson/src/main/scala/tagless/rules.scala
@@ -5,7 +5,7 @@ package jsjson
 import scala.scalajs.js
 import jto.validation.jsjson.Rules
 
-sealed trait RulesGrammar
+trait RulesGrammar
     extends JsonGrammar[Rule]
     with RuleConstraints
     with RulesTypeclasses[js.Dynamic] {
diff --git a/validation-jsjson/src/main/scala/tagless/writes.scala b/validation-jsjson/src/main/scala/tagless/writes.scala
index f5def1c7..ed341139 100644
--- a/validation-jsjson/src/main/scala/tagless/writes.scala
+++ b/validation-jsjson/src/main/scala/tagless/writes.scala
@@ -7,7 +7,7 @@ import jto.validation.jsjson.Writes
 
 import types.op
 
-sealed trait WritesGrammar
+trait WritesGrammar
     extends JsonGrammar[op[Write]#λ]
     with WriteConstraints
     with WritesTypeclasses[js.Dynamic] {
diff --git a/validation-jsonast/shared/src/main/scala/tagless/rules.scala b/validation-jsonast/shared/src/main/scala/tagless/rules.scala
index 164d7007..6ceb0d84 100644
--- a/validation-jsonast/shared/src/main/scala/tagless/rules.scala
+++ b/validation-jsonast/shared/src/main/scala/tagless/rules.scala
@@ -4,7 +4,7 @@ package jsonast
 
 import jto.validation.jsonast._
 
-sealed trait RulesGrammar
+trait RulesGrammar
     extends JsonGrammar[Rule]
     with RuleConstraints
     with RulesTypeclasses[JValue] {
diff --git a/validation-jsonast/shared/src/main/scala/tagless/writes.scala b/validation-jsonast/shared/src/main/scala/tagless/writes.scala
index 4f33f606..263a64bf 100644
--- a/validation-jsonast/shared/src/main/scala/tagless/writes.scala
+++ b/validation-jsonast/shared/src/main/scala/tagless/writes.scala
@@ -6,7 +6,7 @@ import jto.validation.jsonast._
 
 import types.op
 
-sealed trait WritesGrammar
+trait WritesGrammar
     extends JsonGrammar[op[Write]#λ]
     with WriteConstraints
     with WritesTypeclasses[JValue] {
diff --git a/validation-playjson/src/main/scala/tagless/rules.scala b/validation-playjson/src/main/scala/tagless/rules.scala
index 864eacab..d8594f58 100644
--- a/validation-playjson/src/main/scala/tagless/rules.scala
+++ b/validation-playjson/src/main/scala/tagless/rules.scala
@@ -5,7 +5,7 @@ package playjson
 import play.api.libs.json.{JsValue, JsObject, JsArray}
 import jto.validation.playjson.Rules
 
-sealed trait RulesGrammar
+trait RulesGrammar
     extends JsonGrammar[Rule]
     with RuleConstraints
     with RulesTypeclasses[JsValue] {
diff --git a/validation-playjson/src/main/scala/tagless/writes.scala b/validation-playjson/src/main/scala/tagless/writes.scala
index f1f8f072..557c5a8d 100644
--- a/validation-playjson/src/main/scala/tagless/writes.scala
+++ b/validation-playjson/src/main/scala/tagless/writes.scala
@@ -7,7 +7,7 @@ import jto.validation.playjson.Writes
 
 import types.op
 
-sealed trait WritesGrammar
+trait WritesGrammar
     extends JsonGrammar[op[Write]#λ]
     with WriteConstraints
     with WritesTypeclasses[JsValue] {
diff --git a/validation-xml/src/main/scala/tagless/rules.scala b/validation-xml/src/main/scala/tagless/rules.scala
index c6c4b900..d8f19320 100644
--- a/validation-xml/src/main/scala/tagless/rules.scala
+++ b/validation-xml/src/main/scala/tagless/rules.scala
@@ -6,7 +6,7 @@ import jto.validation.xml.Rules
 import shapeless.tag, tag.@@
 import scala.xml.{NodeSeq, Null}
 
-sealed trait RulesGrammar
+trait RulesGrammar
     extends XmlGrammar[List[XML], Rule]
     with RuleConstraints
     with RulesTypeclasses[List[XML]] {
diff --git a/validation-xml/src/main/scala/tagless/writes.scala b/validation-xml/src/main/scala/tagless/writes.scala
index 7c3453b9..33ee150f 100644
--- a/validation-xml/src/main/scala/tagless/writes.scala
+++ b/validation-xml/src/main/scala/tagless/writes.scala
@@ -9,7 +9,7 @@ import shapeless.tag, tag.@@
 import scala.xml.{Null, Text, Attribute, NodeSeq, MetaData, Elem, TopScope}
 import cats.Monoid
 
-sealed trait WritesGrammar
+trait WritesGrammar
     extends XmlGrammar[List[XML], op[Write]#λ]
     with WriteConstraints
     with WritesTypeclasses[List[XML]] {
diff --git a/version.sbt b/version.sbt
index 65e0ce17..5051b751 100644
--- a/version.sbt
+++ b/version.sbt
@@ -1 +1 @@
-version in ThisBuild := "2.1.0"
+version in ThisBuild := "3.0.0-SNAPSHOT"