diff --git a/build.sbt b/build.sbt
index e4f27b72a3ad..c0ff38b603f0 100644
--- a/build.sbt
+++ b/build.sbt
@@ -14,6 +14,9 @@ val `dotty-staging` = Build.`dotty-staging`
 val `dotty-language-server` = Build.`dotty-language-server`
 val `dotty-bench` = Build.`dotty-bench`
 val `dotty-bench-bootstrapped` = Build.`dotty-bench-bootstrapped`
+val `tasty-core` = Build.`tasty-core`
+val `tasty-core-bootstrapped` = Build.`tasty-core-bootstrapped`
+val `tasty-core-scala2` = Build.`tasty-core-scala2`
 val `scala-library` = Build.`scala-library`
 val `scala-compiler` = Build.`scala-compiler`
 val `scala-reflect` = Build.`scala-reflect`
diff --git a/compiler/src/dotty/tools/backend/jvm/GenBCode.scala b/compiler/src/dotty/tools/backend/jvm/GenBCode.scala
index b291a6b0ec44..8601d72d96c1 100644
--- a/compiler/src/dotty/tools/backend/jvm/GenBCode.scala
+++ b/compiler/src/dotty/tools/backend/jvm/GenBCode.scala
@@ -20,13 +20,13 @@ import Decorators._
 
 import java.io.DataOutputStream
 
+import dotty.tools.tasty.{ TastyBuffer, TastyHeaderUnpickler }
 
 import scala.tools.asm
 import scala.tools.asm.Handle
 import scala.tools.asm.tree._
 import tpd._
 import StdNames._
-import dotty.tools.dotc.core.tasty.{TastyBuffer, TastyHeaderUnpickler}
 import dotty.tools.io._
 
 class GenBCode extends Phase {
diff --git a/compiler/src/dotty/tools/dotc/core/NameTags.scala b/compiler/src/dotty/tools/dotc/core/NameTags.scala
index fe351ccc61e7..df4989dafac9 100644
--- a/compiler/src/dotty/tools/dotc/core/NameTags.scala
+++ b/compiler/src/dotty/tools/dotc/core/NameTags.scala
@@ -1,8 +1,6 @@
-package dotty.tools
-package dotc
-package core
+package dotty.tools.dotc.core
 
-import tasty.TastyFormat
+import dotty.tools.tasty.TastyFormat
 
 /** The possible tags of a NameKind */
 object NameTags extends TastyFormat.NameTags {
diff --git a/compiler/src/dotty/tools/dotc/core/classfile/ClassfileParser.scala b/compiler/src/dotty/tools/dotc/core/classfile/ClassfileParser.scala
index df28f90dd188..8fbd636b756e 100644
--- a/compiler/src/dotty/tools/dotc/core/classfile/ClassfileParser.scala
+++ b/compiler/src/dotty/tools/dotc/core/classfile/ClassfileParser.scala
@@ -3,10 +3,11 @@ package dotc
 package core
 package classfile
 
+import dotty.tools.tasty.{ TastyReader, TastyHeaderUnpickler }
+
 import Contexts._, Symbols._, Types._, Names._, StdNames._, NameOps._, Scopes._, Decorators._
 import SymDenotations._, unpickleScala2.Scala2Unpickler._, Constants._, Annotations._, util.Spans._
 import NameKinds.DefaultGetterName
-import dotty.tools.dotc.core.tasty.{TastyHeaderUnpickler, TastyReader}
 import ast.tpd._
 import java.io.{ ByteArrayInputStream, ByteArrayOutputStream, DataInputStream, IOException }
 
@@ -1183,4 +1184,3 @@ class ClassfileParser(
       throw new RuntimeException("bad constant pool tag " + in.buf(start) + " at byte " + start)
   }
 }
-
diff --git a/compiler/src/dotty/tools/dotc/core/quoted/PickledQuotes.scala b/compiler/src/dotty/tools/dotc/core/quoted/PickledQuotes.scala
index bd306960eb76..c6982f1ad5f0 100644
--- a/compiler/src/dotty/tools/dotc/core/quoted/PickledQuotes.scala
+++ b/compiler/src/dotty/tools/dotc/core/quoted/PickledQuotes.scala
@@ -12,11 +12,13 @@ import dotty.tools.dotc.core.Mode
 import dotty.tools.dotc.core.Symbols._
 import dotty.tools.dotc.core.Types._
 import dotty.tools.dotc.core.tasty.TreePickler.Hole
-import dotty.tools.dotc.core.tasty.{PositionPickler, TastyPickler, TastyPrinter, TastyString}
+import dotty.tools.dotc.core.tasty.{ PositionPickler, TastyPickler, TastyPrinter }
 import dotty.tools.dotc.core.tasty.TreeUnpickler.UnpickleMode
 import dotty.tools.dotc.quoted.QuoteContext
 import dotty.tools.dotc.tastyreflect.ReflectionImpl
 
+import dotty.tools.tasty.TastyString
+
 import scala.internal.quoted._
 import scala.reflect.ClassTag
 
diff --git a/compiler/src/dotty/tools/dotc/core/quoted/QuoteUnpickler.scala b/compiler/src/dotty/tools/dotc/core/quoted/QuoteUnpickler.scala
index 7a01d611a94b..b0927b99c3ed 100644
--- a/compiler/src/dotty/tools/dotc/core/quoted/QuoteUnpickler.scala
+++ b/compiler/src/dotty/tools/dotc/core/quoted/QuoteUnpickler.scala
@@ -4,6 +4,8 @@ import dotty.tools.dotc.core.tasty._
 import dotty.tools.dotc.core.tasty.TastyUnpickler.NameTable
 import dotty.tools.dotc.core.tasty.TreeUnpickler.UnpickleMode
 
+import dotty.tools.tasty.TastyReader
+
 object QuoteUnpickler {
   class QuotedTreeSectionUnpickler(posUnpickler: Option[PositionUnpickler], splices: Seq[Any])
     extends DottyUnpickler.TreeSectionUnpickler(posUnpickler, None) {
diff --git a/compiler/src/dotty/tools/dotc/core/tasty/CommentPickler.scala b/compiler/src/dotty/tools/dotc/core/tasty/CommentPickler.scala
index 8f9a54dbc524..1b57588f45a8 100644
--- a/compiler/src/dotty/tools/dotc/core/tasty/CommentPickler.scala
+++ b/compiler/src/dotty/tools/dotc/core/tasty/CommentPickler.scala
@@ -3,7 +3,9 @@ package dotty.tools.dotc.core.tasty
 import dotty.tools.dotc.ast.tpd
 import dotty.tools.dotc.core.Comments.{Comment, CommentsContext, ContextDocstrings}
 import dotty.tools.dotc.core.Contexts.Context
-import dotty.tools.dotc.core.tasty.TastyBuffer.{Addr, NoAddr}
+
+import dotty.tools.tasty.TastyBuffer
+import TastyBuffer.{Addr, NoAddr}
 
 import java.nio.charset.Charset
 
@@ -40,4 +42,3 @@ class CommentPickler(pickler: TastyPickler, addrOfTree: tpd.Tree => Addr)(implic
       }
   }
 }
-
diff --git a/compiler/src/dotty/tools/dotc/core/tasty/CommentUnpickler.scala b/compiler/src/dotty/tools/dotc/core/tasty/CommentUnpickler.scala
index 316a77d13fbf..3b12f6d773c3 100644
--- a/compiler/src/dotty/tools/dotc/core/tasty/CommentUnpickler.scala
+++ b/compiler/src/dotty/tools/dotc/core/tasty/CommentUnpickler.scala
@@ -1,9 +1,11 @@
 package dotty.tools.dotc.core.tasty
 
 import dotty.tools.dotc.core.Comments.Comment
-import dotty.tools.dotc.core.tasty.TastyBuffer.Addr
 import dotty.tools.dotc.util.Spans.Span
 
+import dotty.tools.tasty.{TastyReader, TastyBuffer}
+import TastyBuffer.Addr
+
 import scala.collection.mutable.HashMap
 
 import java.nio.charset.Charset
@@ -29,4 +31,3 @@ class CommentUnpickler(reader: TastyReader) {
   def commentAt(addr: Addr): Option[Comment] =
     comments.get(addr)
 }
-
diff --git a/compiler/src/dotty/tools/dotc/core/tasty/DottyUnpickler.scala b/compiler/src/dotty/tools/dotc/core/tasty/DottyUnpickler.scala
index 967dec8c03e1..40356da7a40c 100644
--- a/compiler/src/dotty/tools/dotc/core/tasty/DottyUnpickler.scala
+++ b/compiler/src/dotty/tools/dotc/core/tasty/DottyUnpickler.scala
@@ -10,6 +10,8 @@ import classfile.ClassfileParser
 import Names.SimpleName
 import TreeUnpickler.UnpickleMode
 
+import dotty.tools.tasty.TastyReader
+
 object DottyUnpickler {
 
   /** Exception thrown if classfile is corrupted */
diff --git a/compiler/src/dotty/tools/dotc/core/tasty/NameBuffer.scala b/compiler/src/dotty/tools/dotc/core/tasty/NameBuffer.scala
index 388de191823e..63b724b051f8 100644
--- a/compiler/src/dotty/tools/dotc/core/tasty/NameBuffer.scala
+++ b/compiler/src/dotty/tools/dotc/core/tasty/NameBuffer.scala
@@ -3,11 +3,13 @@ package dotc
 package core
 package tasty
 
+import dotty.tools.tasty.TastyBuffer
+import TastyBuffer._
+
 import collection.mutable
 import Names.{Name, chrs, SimpleName, DerivedName, TypeName}
 import NameKinds._
 import Decorators._
-import TastyBuffer._
 import scala.io.Codec
 
 class NameBuffer extends TastyBuffer(10000) {
diff --git a/compiler/src/dotty/tools/dotc/core/tasty/PositionPickler.scala b/compiler/src/dotty/tools/dotc/core/tasty/PositionPickler.scala
index 280d858eda69..8a7095b21dd3 100644
--- a/compiler/src/dotty/tools/dotc/core/tasty/PositionPickler.scala
+++ b/compiler/src/dotty/tools/dotc/core/tasty/PositionPickler.scala
@@ -3,6 +3,10 @@ package dotc
 package core
 package tasty
 
+import dotty.tools.tasty.TastyFormat.SOURCE
+import dotty.tools.tasty.TastyBuffer
+import TastyBuffer._
+
 import ast._
 import ast.Trees._
 import ast.Trees.WithLazyField
@@ -10,9 +14,7 @@ import util.{SourceFile, NoSource}
 import core._
 import Contexts._, Symbols._, Annotations._, Decorators._
 import collection.mutable
-import TastyBuffer._
 import util.Spans._
-import TastyFormat.SOURCE
 
 class PositionPickler(pickler: TastyPickler, addrOfTree: untpd.Tree => Addr) {
   val buf: TastyBuffer = new TastyBuffer(5000)
diff --git a/compiler/src/dotty/tools/dotc/core/tasty/PositionUnpickler.scala b/compiler/src/dotty/tools/dotc/core/tasty/PositionUnpickler.scala
index 52194c6d2a4f..4d15b39999f6 100644
--- a/compiler/src/dotty/tools/dotc/core/tasty/PositionUnpickler.scala
+++ b/compiler/src/dotty/tools/dotc/core/tasty/PositionUnpickler.scala
@@ -3,10 +3,12 @@ package dotc
 package core
 package tasty
 
+import dotty.tools.tasty.{TastyFormat, TastyBuffer, TastyReader}
+import TastyFormat.SOURCE
+import TastyBuffer.{Addr, NameRef}
+
 import util.Spans._
 import collection.{mutable, Map}
-import TastyBuffer.{Addr, NameRef}
-import TastyFormat.SOURCE
 import Names.TermName
 
 /** Unpickler for tree positions */
@@ -61,4 +63,3 @@ class PositionUnpickler(reader: TastyReader, nameAtRef: NameRef => TermName) {
   def spanAt(addr: Addr): Span = spans.getOrElse(addr, NoSpan)
   def sourcePathAt(addr: Addr): String = sourcePaths.getOrElse(addr, "")
 }
-
diff --git a/compiler/src/dotty/tools/dotc/core/tasty/TastyClassName.scala b/compiler/src/dotty/tools/dotc/core/tasty/TastyClassName.scala
index 6ca530997717..12e8a60c5a28 100644
--- a/compiler/src/dotty/tools/dotc/core/tasty/TastyClassName.scala
+++ b/compiler/src/dotty/tools/dotc/core/tasty/TastyClassName.scala
@@ -2,11 +2,13 @@ package dotty.tools.dotc
 package core
 package tasty
 
+import dotty.tools.tasty.{TastyBuffer, TastyReader}
+import TastyBuffer.NameRef
+
 import Contexts._, Decorators._
 import Names.{Name, TermName}
 import StdNames.nme
 import TastyUnpickler._
-import TastyBuffer.NameRef
 import util.Spans.offsetToInt
 import printing.Highlighting._
 
@@ -20,7 +22,7 @@ class TastyClassName(bytes: Array[Byte]) {
   def readName(): Option[(TermName, TermName)] = unpickle(new TreeSectionUnpickler)
 
   class TreeSectionUnpickler extends SectionUnpickler[(TermName, TermName)](TreePickler.sectionName) {
-    import TastyFormat._
+    import dotty.tools.tasty.TastyFormat._
     def unpickle(reader: TastyReader, tastyName: NameTable): (TermName, TermName) = {
       import reader._
       def readName() = {
diff --git a/compiler/src/dotty/tools/dotc/core/tasty/TastyHTMLPrinter.scala b/compiler/src/dotty/tools/dotc/core/tasty/TastyHTMLPrinter.scala
index e6d2ea258760..f8f6c11ce6c1 100644
--- a/compiler/src/dotty/tools/dotc/core/tasty/TastyHTMLPrinter.scala
+++ b/compiler/src/dotty/tools/dotc/core/tasty/TastyHTMLPrinter.scala
@@ -2,10 +2,11 @@ package dotty.tools.dotc
 package core
 package tasty
 
+import dotty.tools.tasty.TastyBuffer.NameRef
+
 import Contexts._, Decorators._
 import Names.Name
 import TastyUnpickler._
-import TastyBuffer.NameRef
 import util.Spans.offsetToInt
 import printing.Highlighting._
 
diff --git a/compiler/src/dotty/tools/dotc/core/tasty/TastyPickler.scala b/compiler/src/dotty/tools/dotc/core/tasty/TastyPickler.scala
index a0ead8d38dbe..3ae6cb79510d 100644
--- a/compiler/src/dotty/tools/dotc/core/tasty/TastyPickler.scala
+++ b/compiler/src/dotty/tools/dotc/core/tasty/TastyPickler.scala
@@ -3,9 +3,11 @@ package dotc
 package core
 package tasty
 
+import dotty.tools.tasty.{TastyBuffer, TastyFormat, TastyHash}
 import TastyFormat._
-import collection.mutable
 import TastyBuffer._
+
+import collection.mutable
 import core.Symbols.{Symbol, ClassSymbol}
 import ast.tpd
 import Decorators._
@@ -78,4 +80,3 @@ class TastyPickler(val rootCls: ClassSymbol) {
 
   val treePkl: TreePickler = new TreePickler(this)
 }
-
diff --git a/compiler/src/dotty/tools/dotc/core/tasty/TastyPrinter.scala b/compiler/src/dotty/tools/dotc/core/tasty/TastyPrinter.scala
index 3a007d667371..3dea03543393 100644
--- a/compiler/src/dotty/tools/dotc/core/tasty/TastyPrinter.scala
+++ b/compiler/src/dotty/tools/dotc/core/tasty/TastyPrinter.scala
@@ -2,10 +2,12 @@ package dotty.tools.dotc
 package core
 package tasty
 
+import dotty.tools.tasty.{TastyBuffer, TastyReader}
+import TastyBuffer.{Addr, NameRef}
+
 import Contexts._, Decorators._
 import Names.Name
 import TastyUnpickler._
-import TastyBuffer.{Addr, NameRef}
 import util.Spans.offsetToInt
 import printing.Highlighting._
 
@@ -49,7 +51,7 @@ class TastyPrinter(bytes: Array[Byte])(implicit ctx: Context) {
   }
 
   class TreeSectionUnpickler extends SectionUnpickler[String](TreePickler.sectionName) {
-    import TastyFormat._
+    import dotty.tools.tasty.TastyFormat._
 
     private val sb: StringBuilder = new StringBuilder
 
diff --git a/compiler/src/dotty/tools/dotc/core/tasty/TastyString.scala b/compiler/src/dotty/tools/dotc/core/tasty/TastyString.scala
index cef20a5223e6..6222377716ab 100644
--- a/compiler/src/dotty/tools/dotc/core/tasty/TastyString.scala
+++ b/compiler/src/dotty/tools/dotc/core/tasty/TastyString.scala
@@ -1,4 +1,4 @@
-package dotty.tools.dotc.core.tasty
+package dotty.tools.tasty
 
 import java.io._
 import java.util.Base64
@@ -25,4 +25,3 @@ object TastyString {
     Base64.getDecoder().decode(string.result().getBytes(UTF_8))
   }
 }
-
diff --git a/compiler/src/dotty/tools/dotc/core/tasty/TastyUnpickler.scala b/compiler/src/dotty/tools/dotc/core/tasty/TastyUnpickler.scala
index 1d7d0f825686..bc40900b2fbb 100644
--- a/compiler/src/dotty/tools/dotc/core/tasty/TastyUnpickler.scala
+++ b/compiler/src/dotty/tools/dotc/core/tasty/TastyUnpickler.scala
@@ -2,14 +2,15 @@ package dotty.tools.dotc
 package core
 package tasty
 
-import scala.collection.mutable
+import dotty.tools.tasty.{TastyFormat, TastyBuffer, TastyReader, TastyHeaderUnpickler}
 import TastyFormat.NameTags._
 import TastyBuffer.NameRef
+
+import scala.collection.mutable
 import Names.{TermName, termName, EmptyTermName}
 import NameKinds._
 
 object TastyUnpickler {
-  class UnpickleException(msg: String) extends RuntimeException(msg)
 
   abstract class SectionUnpickler[R](val name: String) {
     def unpickle(reader: TastyReader, nameAtRef: NameTable): R
diff --git a/compiler/src/dotty/tools/dotc/core/tasty/TreeBuffer.scala b/compiler/src/dotty/tools/dotc/core/tasty/TreeBuffer.scala
index 08ebedfb054c..345dde2aad75 100644
--- a/compiler/src/dotty/tools/dotc/core/tasty/TreeBuffer.scala
+++ b/compiler/src/dotty/tools/dotc/core/tasty/TreeBuffer.scala
@@ -3,8 +3,11 @@ package dotc
 package core
 package tasty
 
-import util.Util.{bestFit, dble}
+import dotty.tools.tasty.util.Util.dble
+import dotty.tools.tasty.TastyBuffer
 import TastyBuffer.{Addr, NoAddr, AddrWidth}
+
+import util.Util.bestFit
 import config.Printers.pickling
 import ast.untpd.Tree
 
diff --git a/compiler/src/dotty/tools/dotc/core/tasty/TreePickler.scala b/compiler/src/dotty/tools/dotc/core/tasty/TreePickler.scala
index 19044baac2d5..e5fab768f976 100644
--- a/compiler/src/dotty/tools/dotc/core/tasty/TreePickler.scala
+++ b/compiler/src/dotty/tools/dotc/core/tasty/TreePickler.scala
@@ -3,14 +3,15 @@ package dotc
 package core
 package tasty
 
+import dotty.tools.tasty.TastyFormat._
+import dotty.tools.tasty.TastyBuffer._
+
 import ast.Trees._
 import ast.{untpd, tpd}
-import TastyFormat._
 import Contexts._, Symbols._, Types._, Names._, Constants._, Decorators._, Annotations._, Flags._
 import typer.Inliner
 import NameKinds._
 import StdNames.nme
-import TastyBuffer._
 import transform.SymUtils._
 import printing.Printer
 import printing.Texts._
diff --git a/compiler/src/dotty/tools/dotc/core/tasty/TreeUnpickler.scala b/compiler/src/dotty/tools/dotc/core/tasty/TreeUnpickler.scala
index acacd0f0cfdd..4bfafc68e752 100644
--- a/compiler/src/dotty/tools/dotc/core/tasty/TreeUnpickler.scala
+++ b/compiler/src/dotty/tools/dotc/core/tasty/TreeUnpickler.scala
@@ -24,6 +24,8 @@ import ast.{TreeTypeMap, Trees, tpd, untpd}
 import Trees._
 import Decorators._
 import transform.SymUtils._
+
+import dotty.tools.tasty.{TastyBuffer, TastyReader}
 import TastyBuffer._
 
 import scala.annotation.{switch, tailrec}
@@ -33,6 +35,8 @@ import config.Printers.pickling
 import core.quoted.PickledQuotes
 import dotty.tools.dotc.quoted.QuoteContext
 
+import dotty.tools.tasty.TastyFormat._
+
 import scala.quoted
 import scala.internal.quoted.{TastyTreeExpr, TreeType}
 import scala.annotation.constructorOnly
@@ -49,7 +53,6 @@ class TreeUnpickler(reader: TastyReader,
                     posUnpicklerOpt: Option[PositionUnpickler],
                     commentUnpicklerOpt: Option[CommentUnpickler],
                     splices: Seq[Any]) {
-  import TastyFormat._
   import TreeUnpickler._
   import tpd._
 
@@ -1454,5 +1457,3 @@ object TreeUnpickler {
 
   class TreeWithoutOwner extends Exception
 }
-
-
diff --git a/compiler/src/dotty/tools/dotc/util/Util.scala b/compiler/src/dotty/tools/dotc/util/Util.scala
index bf34ff0157ed..7b6e3b1136ff 100644
--- a/compiler/src/dotty/tools/dotc/util/Util.scala
+++ b/compiler/src/dotty/tools/dotc/util/Util.scala
@@ -1,5 +1,4 @@
 package dotty.tools.dotc.util
-import reflect.ClassTag
 
 object Util {
 
@@ -23,10 +22,4 @@ object Util {
     else recur(0, length, initMid)
   }
 
-  /** An array twice the size of given array, with existing elements copied over */
-  def dble[T: ClassTag](arr: Array[T]): Array[T] = {
-    val arr1 = new Array[T](arr.length * 2)
-    System.arraycopy(arr, 0, arr1, 0, arr.length)
-    arr1
-  }
 }
diff --git a/compiler/test/dotty/Properties.scala b/compiler/test/dotty/Properties.scala
index f2195e143746..ed377859a047 100644
--- a/compiler/test/dotty/Properties.scala
+++ b/compiler/test/dotty/Properties.scala
@@ -53,6 +53,9 @@ object Properties {
   /** dotty-staging jar */
   def dottyStaging: String = sys.props("dotty.tests.classes.dottyStaging")
 
+  /** tasty-core jar */
+  def tastyCore: String = sys.props("dotty.tests.classes.tastyCore")
+
   /** compiler-interface jar */
   def compilerInterface: String = sys.props("dotty.tests.classes.compilerInterface")
 
diff --git a/compiler/test/dotty/tools/dotc/BootstrappedOnlyCompilationTests.scala b/compiler/test/dotty/tools/dotc/BootstrappedOnlyCompilationTests.scala
index 61da70fef499..95b2fd978068 100644
--- a/compiler/test/dotty/tools/dotc/BootstrappedOnlyCompilationTests.scala
+++ b/compiler/test/dotty/tools/dotc/BootstrappedOnlyCompilationTests.scala
@@ -50,6 +50,7 @@ class BootstrappedOnlyCompilationTests extends ParallelTesting {
       compileDir("compiler/src/dotty/tools/dotc/typer", withCompilerOptions),
       compileDir("compiler/src/dotty/tools/dotc/util", withCompilerOptions),
       compileDir("compiler/src/dotty/tools/io", withCompilerOptions),
+      compileDir("tasty/src/dotty/tools/tasty", withCompilerOptions),
       compileList(
         "testIssue6460",
         List(
@@ -163,7 +164,8 @@ class BootstrappedOnlyCompilationTests extends ParallelTesting {
       compileFile("tests/pos/pickleinf.scala", picklingWithCompilerOptions),
       compileDir("compiler/src/dotty/tools/dotc/core/classfile", picklingWithCompilerOptions),
       compileDir("compiler/src/dotty/tools/dotc/core/tasty", picklingWithCompilerOptions),
-      compileDir("compiler/src/dotty/tools/dotc/core/unpickleScala2", picklingWithCompilerOptions)
+      compileDir("compiler/src/dotty/tools/dotc/core/unpickleScala2", picklingWithCompilerOptions),
+      compileDir("tasty/src/dotty/tools/tasty", picklingWithCompilerOptions)
     ).limitThreads(4).checkCompile()
   }
 
diff --git a/compiler/test/dotty/tools/dotc/CompilationTests.scala b/compiler/test/dotty/tools/dotc/CompilationTests.scala
index fcc591cf9057..702860e379a4 100644
--- a/compiler/test/dotty/tools/dotc/CompilationTests.scala
+++ b/compiler/test/dotty/tools/dotc/CompilationTests.scala
@@ -210,7 +210,8 @@ class CompilationTests extends ParallelTesting {
       defaultOutputDir + dotty1Group + "/dotty/" + sep +
       // and the other compiler dependenies:
       Properties.compilerInterface + sep + Properties.scalaLibrary + sep + Properties.scalaAsm + sep +
-      Properties.dottyInterfaces + sep + Properties.jlineTerminal + sep + Properties.jlineReader,
+      Properties.dottyInterfaces + sep + Properties.tastyCore + sep + Properties.jlineTerminal + sep +
+      Properties.jlineReader,
       Array("-Ycheck-reentrant", "-Yemit-tasty-in-class")
     )
 
diff --git a/compiler/test/dotty/tools/dotc/TastyHashTest.scala b/compiler/test/dotty/tools/dotc/TastyHashTest.scala
index b8cb5c9c0bc2..09d631d97377 100644
--- a/compiler/test/dotty/tools/dotc/TastyHashTest.scala
+++ b/compiler/test/dotty/tools/dotc/TastyHashTest.scala
@@ -3,7 +3,7 @@ package dotty.tools.dotc
 import org.junit.Test
 import org.junit.Assert.assertEquals
 
-import dotty.tools.dotc.core.tasty.TastyHash.pjwHash64
+import dotty.tools.tasty.TastyHash.pjwHash64
 
 class TastyHashTest {
   @Test def pjwHash64Tests(): Unit = {
diff --git a/compiler/test/dotty/tools/vulpix/TestConfiguration.scala b/compiler/test/dotty/tools/vulpix/TestConfiguration.scala
index db121cf00932..931f56d21048 100644
--- a/compiler/test/dotty/tools/vulpix/TestConfiguration.scala
+++ b/compiler/test/dotty/tools/vulpix/TestConfiguration.scala
@@ -32,6 +32,7 @@ object TestConfiguration {
     Properties.compilerInterface,
     Properties.dottyInterfaces,
     Properties.dottyLibrary,
+    Properties.tastyCore,
     Properties.dottyCompiler
   ))
 
diff --git a/dist/bin/common b/dist/bin/common
index 085b0f386300..0c7822f6c953 100755
--- a/dist/bin/common
+++ b/dist/bin/common
@@ -108,6 +108,7 @@ DOTTY_COMP=$(find_lib "*dotty-compiler*")
 DOTTY_INTF=$(find_lib "*dotty-interfaces*")
 DOTTY_LIB=$(find_lib "*dotty-library*")
 DOTTY_STAGING=$(find_lib "*dotty-staging*")
+TASTY_CORE=$(find_lib "*tasty-core*")
 SCALA_ASM=$(find_lib "*scala-asm*")
 SCALA_LIB=$(find_lib "*scala-library*")
 SBT_INTF=$(find_lib "*compiler-interface*")
diff --git a/dist/bin/dotc b/dist/bin/dotc
index b442f27a36c5..532224705709 100755
--- a/dist/bin/dotc
+++ b/dist/bin/dotc
@@ -50,6 +50,7 @@ classpathArgs () {
   # echo "dotty-compiler: $DOTTY_COMP"
   # echo "dotty-interface: $DOTTY_INTF"
   # echo "dotty-library: $DOTTY_LIB"
+  # echo "tasty-core: $TASTY_CORE"
   # echo "scala-asm: $SCALA_ASM"
   # echo "scala-lib: $SCALA_LIB"
   # echo "sbt-intface: $SBT_INTF"
@@ -61,6 +62,7 @@ classpathArgs () {
   toolchain+="$SBT_INTF$PSEP"
   toolchain+="$DOTTY_INTF$PSEP"
   toolchain+="$DOTTY_COMP$PSEP"
+  toolchain+="$TASTY_CORE$PSEP"
   toolchain+="$DOTTY_STAGING$PSEP"
 
   # jine
@@ -88,7 +90,7 @@ case "$1" in
          -run) PROG_NAME="$ReplMain" && shift ;;
       -colors) colors=true && shift ;;
    -no-colors) unset colors && shift ;;
-  -with-compiler) jvm_cp_args="$PSEP$DOTTY_COMP" && shift ;;
+  -with-compiler) jvm_cp_args="$PSEP$DOTTY_COMP$PSEP$TASTY_CORE" && shift ;;
 
           # break out -D and -J options and add them to java_args so
           # they reach the JVM in time to do some good. The -D options
diff --git a/dist/bin/dotd b/dist/bin/dotd
index 0475e81ad68a..ff4cce9788ce 100755
--- a/dist/bin/dotd
+++ b/dist/bin/dotd
@@ -76,7 +76,7 @@ ST4_LIB=$(find_lib "*ST4*")
 # Set jsoup dep:
 JSOUP_LIB=$(find_lib "*jsoup*")
 
-CLASS_PATH="$DOTTY_LIB$PSEP$DOTTY_COMP$PSEP$DOTTY_DOC_LIB$PSEP$DOTTY_INTF$PSEP$SBT_INTF$PSEP$DOTTY_STAGING"
+CLASS_PATH="$DOTTY_LIB$PSEP$DOTTY_COMP$PSEP$TASTY_CORE$PSEP$DOTTY_DOC_LIB$PSEP$DOTTY_INTF$PSEP$SBT_INTF$PSEP$DOTTY_STAGING"
 CLASS_PATH="$CLASS_PATH$PSEP$SCALA_LIB"
 CLASS_PATH="$CLASS_PATH$PSEP$FLEXMARK_LIBS"
 CLASS_PATH="$CLASS_PATH$PSEP$JACKSON_LIBS"
diff --git a/dist/bin/dotr b/dist/bin/dotr
index 5d8808a3ed4d..029a0aee97af 100755
--- a/dist/bin/dotr
+++ b/dist/bin/dotr
@@ -102,7 +102,7 @@ elif [ $execute_repl == true ] || [ ${#residual_args[@]} -ne 0 ]; then
     echo "warning: multiple classpaths are found, dotr only use the last one."
   fi
   if [ $with_compiler == true ]; then
-    cp_arg+="$PSEP$DOTTY_COMP$PSEP$DOTTY_INTF$PSEP$SCALA_ASM$PSEP$DOTTY_STAGING"
+    cp_arg+="$PSEP$DOTTY_COMP$PSEP$TASTY_CORE$PSEP$DOTTY_INTF$PSEP$SCALA_ASM$PSEP$DOTTY_STAGING"
   fi
   eval exec "\"$JAVACMD\"" "$DEBUG"  "-classpath \"$cp_arg\"" "${jvm_options[@]}" "${residual_args[@]}"
 else
diff --git a/language-server/src/dotty/tools/languageserver/decompiler/TastyDecompilerService.scala b/language-server/src/dotty/tools/languageserver/decompiler/TastyDecompilerService.scala
index 8494b9630712..cf2faf679ac8 100644
--- a/language-server/src/dotty/tools/languageserver/decompiler/TastyDecompilerService.scala
+++ b/language-server/src/dotty/tools/languageserver/decompiler/TastyDecompilerService.scala
@@ -6,7 +6,8 @@ import java.net.URI
 import java.nio.file._
 import java.util.concurrent.CompletableFuture
 
-import dotc.core.tasty.TastyUnpickler.UnpickleException
+import dotty.tools.tasty.UnpickleException
+
 import dotc.fromtasty.TastyFileUtil
 
 import org.eclipse.lsp4j.jsonrpc.services._
diff --git a/project/Build.scala b/project/Build.scala
index b626fcb32b58..803d2ef63918 100644
--- a/project/Build.scala
+++ b/project/Build.scala
@@ -252,6 +252,13 @@ object Build {
     autoScalaLibrary := false
   )
 
+  lazy val commonScala2Settings = commonSettings ++ Seq(
+    scalaVersion := stdlibVersion(Bootstrapped),
+    moduleName ~= { _.stripSuffix("-scala2") },
+    version := dottyVersion,
+    target := baseDirectory.value / ".." / "out" / "scala-2" / name.value,
+  )
+
   // Settings used when compiling dotty with the reference compiler
   lazy val commonNonBootstrappedSettings = commonDottySettings ++ Seq(
     unmanagedSourceDirectories in Compile += baseDirectory.value / "src-non-bootstrapped",
@@ -298,12 +305,13 @@ object Build {
       // compiler instances. This cache is invalidated based on timestamps
       // however this is only implemented on jars, directories are never
       // invalidated.
+      val tastyCore = packageBin.in(`tasty-core`, Compile).value
       val dottyLibrary = packageBin.in(`dotty-library`, Compile).value
       val dottyInterfaces = packageBin.in(`dotty-interfaces`, Compile).value
       val dottyCompiler = packageBin.in(`dotty-compiler`, Compile).value
       val dottyDoc = packageBin.in(`dotty-doc`, Compile).value
 
-      val allJars = Seq(dottyLibrary, dottyInterfaces, dottyCompiler, dottyDoc) ++ externalNonBootstrappedDeps.map(_.data)
+      val allJars = Seq(tastyCore, dottyLibrary, dottyInterfaces, dottyCompiler, dottyDoc) ++ externalNonBootstrappedDeps.map(_.data)
 
       makeScalaInstance(
         state.value,
@@ -361,7 +369,6 @@ object Build {
   private lazy val dottydocClasspath = Def.task {
     val jars = (packageAll in `dotty-compiler`).value
     val dottyLib = jars("dotty-library")
-    val dottyInterfaces = jars("dotty-interfaces")
     val otherDeps = (dependencyClasspath in Compile).value.map(_.data).mkString(File.pathSeparator)
     val externalDeps = externalCompilerClasspathTask.value
     dottyLib + File.pathSeparator + findArtifactPath(externalDeps, "scala-library")
@@ -512,6 +519,7 @@ object Build {
           "-Ddotty.tests.classes.dottyInterfaces=" + jars("dotty-interfaces"),
           "-Ddotty.tests.classes.dottyLibrary=" + jars("dotty-library"),
           "-Ddotty.tests.classes.dottyCompiler=" + jars("dotty-compiler"),
+          "-Ddotty.tests.classes.tastyCore=" + jars("tasty-core"),
           "-Ddotty.tests.classes.compilerInterface=" + findArtifactPath(externalDeps, "compiler-interface"),
           "-Ddotty.tests.classes.scalaLibrary=" + findArtifactPath(externalDeps, "scala-library"),
           "-Ddotty.tests.classes.scalaAsm=" + findArtifactPath(externalDeps, "scala-asm"),
@@ -573,7 +581,8 @@ object Build {
           val dottyCompiler = jars("dotty-compiler")
           val dottyStaging = jars("dotty-staging")
           val dottyInterfaces = jars("dotty-interfaces")
-          run(insertClasspathInArgs(args1, List(dottyCompiler, dottyInterfaces, asm, dottyStaging).mkString(File.pathSeparator)))
+          val tastyCore = jars("tasty-core")
+          run(insertClasspathInArgs(args1, List(dottyCompiler, dottyInterfaces, asm, dottyStaging, tastyCore).mkString(File.pathSeparator)))
         } else run(args)
       },
 
@@ -647,8 +656,9 @@ object Build {
       }
       val dottyInterfaces = jars("dotty-interfaces")
       val dottyStaging = jars("dotty-staging")
+      val tastyCore = jars("tasty-core")
       val asm = findArtifactPath(externalDeps, "scala-asm")
-      extraClasspath ++= Seq(dottyCompiler, dottyInterfaces, asm, dottyStaging)
+      extraClasspath ++= Seq(dottyCompiler, dottyInterfaces, asm, dottyStaging, tastyCore)
     }
 
     val fullArgs = main :: insertClasspathInArgs(args, extraClasspath.mkString(File.pathSeparator))
@@ -669,12 +679,13 @@ object Build {
         Map(
           "dotty-interfaces"    -> packageBin.in(`dotty-interfaces`, Compile).value,
           "dotty-compiler"      -> packageBin.in(Compile).value,
+          "tasty-core"          -> packageBin.in(`tasty-core`, Compile).value,
 
           // NOTE: Using dotty-library-bootstrapped here is intentional: when
           // running the compiler, we should always have the bootstrapped
           // library on the compiler classpath since the non-bootstrapped one
           // may not be binary-compatible.
-          "dotty-library"       -> packageBin.in(`dotty-library-bootstrapped`, Compile).value,
+          "dotty-library"       -> packageBin.in(`dotty-library-bootstrapped`, Compile).value
         ).mapValues(_.getAbsolutePath)
       }
     }.value,
@@ -697,6 +708,7 @@ object Build {
       packageAll.in(`dotty-compiler`).value ++ Seq(
         "dotty-compiler" -> packageBin.in(Compile).value.getAbsolutePath,
         "dotty-staging"  -> packageBin.in(LocalProject("dotty-staging"), Compile).value.getAbsolutePath,
+        "tasty-core"     -> packageBin.in(LocalProject("tasty-core-bootstrapped"), Compile).value.getAbsolutePath,
       )
     }
   )
@@ -743,6 +755,22 @@ object Build {
         (unmanagedSourceDirectories in (`dotty-library-bootstrapped`, Compile)).value,
     )
 
+  lazy val tastyCoreSettings = Seq(
+    scalacOptions ~= { old =>
+      val (language, other) = old.partition(_.startsWith("-language:"))
+      other :+ (language.headOption.map(_ + ",Scala2Compat").getOrElse("-language:Scala2Compat"))
+    }
+  )
+
+  lazy val `tasty-core` = project.in(file("tasty")).asTastyCore(NonBootstrapped)
+  lazy val `tasty-core-bootstrapped`: Project = project.in(file("tasty")).asTastyCore(Bootstrapped)
+  lazy val `tasty-core-scala2`: Project = project.in(file("tasty")).asTastyCoreScala2
+
+  def tastyCore(implicit mode: Mode): Project = mode match {
+    case NonBootstrapped => `tasty-core`
+    case Bootstrapped => `tasty-core-bootstrapped`
+  }
+
   lazy val `dotty-staging` = project.in(file("staging")).
     withCommonSettings(Bootstrapped).
     // We want the compiler to be present in the compiler classpath when compiling this project but not
@@ -1053,6 +1081,7 @@ object Build {
         publishLocal in `dotty-interfaces`,
         publishLocal in `dotty-compiler-bootstrapped`,
         publishLocal in `dotty-library-bootstrapped`,
+        publishLocal in `tasty-core-bootstrapped`,
         publishLocal in `dotty-staging`,
         publishLocal in `scala-library`,
         publishLocal in `scala-reflect`,
@@ -1129,6 +1158,7 @@ object Build {
         (publishLocal in `dotty-interfaces`).value
         (publishLocal in `scala-library`).value
         (publishLocal in `scala-reflect`).value
+        (publishLocal in `tasty-core-bootstrapped`).value
         (publishLocal in `dotty-library-bootstrapped`).value
         (publishLocal in `dotty-doc-bootstrapped`).value
         (publishLocal in `dotty-compiler-bootstrapped`).value
@@ -1263,8 +1293,9 @@ object Build {
 
     // FIXME: we do not aggregate `bin` because its tests delete jars, thus breaking other tests
     def asDottyRoot(implicit mode: Mode): Project = project.withCommonSettings.
-      aggregate(`dotty-interfaces`, dottyLibrary, dottyCompiler, dottyDoc, `dotty-sbt-bridge`).
+      aggregate(`dotty-interfaces`, dottyLibrary, dottyCompiler, tastyCore, dottyDoc, `dotty-sbt-bridge`).
       bootstrappedAggregate(`scala-library`, `scala-compiler`, `scala-reflect`, scalap, `dotty-language-server`, `dotty-staging`).
+      dependsOn(tastyCore).
       dependsOn(dottyCompiler).
       dependsOn(dottyLibrary).
       nonBootstrappedSettings(
@@ -1274,6 +1305,7 @@ object Build {
     def asDottyCompiler(implicit mode: Mode): Project = project.withCommonSettings.
       dependsOn(`dotty-interfaces`).
       dependsOn(dottyLibrary).
+      dependsOn(tastyCore).
       settings(dottyCompilerSettings)
 
     def asDottyLibrary(implicit mode: Mode): Project = project.withCommonSettings.
@@ -1282,6 +1314,12 @@ object Build {
       ).
       settings(dottyLibrarySettings)
 
+    def asTastyCore(implicit mode: Mode): Project = project.withCommonSettings.
+      dependsOn(dottyLibrary).
+      settings(tastyCoreSettings)
+
+    def asTastyCoreScala2: Project = project.settings(commonScala2Settings)
+
     def asDottyDoc(implicit mode: Mode): Project = project.withCommonSettings.
       dependsOn(dottyCompiler, dottyCompiler % "test->test").
       settings(dottyDocSettings)
@@ -1294,7 +1332,7 @@ object Build {
     def asDist(implicit mode: Mode): Project = project.
       enablePlugins(PackPlugin).
       withCommonSettings.
-      dependsOn(`dotty-interfaces`, dottyCompiler, dottyLibrary, `dotty-staging`, dottyDoc).
+      dependsOn(`dotty-interfaces`, dottyCompiler, dottyLibrary, tastyCore, `dotty-staging`, dottyDoc).
       settings(commonDistSettings).
       bootstrappedSettings(
         target := baseDirectory.value / "target" // override setting in commonBootstrappedSettings
diff --git a/compiler/src/dotty/tools/dotc/core/tasty/TastyBuffer.scala b/tasty/src/dotty/tools/tasty/TastyBuffer.scala
similarity index 98%
rename from compiler/src/dotty/tools/dotc/core/tasty/TastyBuffer.scala
rename to tasty/src/dotty/tools/tasty/TastyBuffer.scala
index 8d188bb64cd7..1d48027087f5 100644
--- a/compiler/src/dotty/tools/dotc/core/tasty/TastyBuffer.scala
+++ b/tasty/src/dotty/tools/tasty/TastyBuffer.scala
@@ -1,7 +1,4 @@
-package dotty.tools
-package dotc
-package core
-package tasty
+package dotty.tools.tasty
 
 import util.Util.dble
 
diff --git a/compiler/src/dotty/tools/dotc/core/tasty/TastyFormat.scala b/tasty/src/dotty/tools/tasty/TastyFormat.scala
similarity index 99%
rename from compiler/src/dotty/tools/dotc/core/tasty/TastyFormat.scala
rename to tasty/src/dotty/tools/tasty/TastyFormat.scala
index b6c9fb0ee38b..3f516efe638c 100644
--- a/compiler/src/dotty/tools/dotc/core/tasty/TastyFormat.scala
+++ b/tasty/src/dotty/tools/tasty/TastyFormat.scala
@@ -1,6 +1,4 @@
-package dotty.tools.dotc
-package core
-package tasty
+package dotty.tools.tasty
 
 /************************************************************
 Notation:
@@ -505,7 +503,6 @@ object TastyFormat {
        | DEFAULTparameterized
        | STABLE
        | EXTENSION
-       | GIVEN
        | PARAMsetter
        | EXPORTED
        | OPEN
diff --git a/compiler/src/dotty/tools/dotc/core/tasty/TastyHash.scala b/tasty/src/dotty/tools/tasty/TastyHash.scala
similarity index 92%
rename from compiler/src/dotty/tools/dotc/core/tasty/TastyHash.scala
rename to tasty/src/dotty/tools/tasty/TastyHash.scala
index 4ffc1965202e..aff663f42a8d 100644
--- a/compiler/src/dotty/tools/dotc/core/tasty/TastyHash.scala
+++ b/tasty/src/dotty/tools/tasty/TastyHash.scala
@@ -1,4 +1,4 @@
-package dotty.tools.dotc.core.tasty
+package dotty.tools.tasty
 
 object TastyHash {
 
@@ -20,4 +20,3 @@ object TastyHash {
     h
   }
 }
-
diff --git a/compiler/src/dotty/tools/dotc/core/tasty/TastyHeaderUnpickler.scala b/tasty/src/dotty/tools/tasty/TastyHeaderUnpickler.scala
similarity index 78%
rename from compiler/src/dotty/tools/dotc/core/tasty/TastyHeaderUnpickler.scala
rename to tasty/src/dotty/tools/tasty/TastyHeaderUnpickler.scala
index 5fd56c18af59..05e421750411 100644
--- a/compiler/src/dotty/tools/dotc/core/tasty/TastyHeaderUnpickler.scala
+++ b/tasty/src/dotty/tools/tasty/TastyHeaderUnpickler.scala
@@ -1,11 +1,8 @@
-package dotty.tools.dotc
-package core
-package tasty
+package dotty.tools.tasty
 
 import java.util.UUID
 
-import dotty.tools.dotc.core.tasty.TastyFormat.{MajorVersion, MinorVersion, header}
-import dotty.tools.dotc.core.tasty.TastyUnpickler.UnpickleException
+import TastyFormat.{MajorVersion, MinorVersion, header}
 
 class TastyHeaderUnpickler(reader: TastyReader) {
   import reader._
diff --git a/compiler/src/dotty/tools/dotc/core/tasty/TastyReader.scala b/tasty/src/dotty/tools/tasty/TastyReader.scala
similarity index 98%
rename from compiler/src/dotty/tools/dotc/core/tasty/TastyReader.scala
rename to tasty/src/dotty/tools/tasty/TastyReader.scala
index 2ad0c9ee9d7d..31407f7a4ab8 100644
--- a/compiler/src/dotty/tools/dotc/core/tasty/TastyReader.scala
+++ b/tasty/src/dotty/tools/tasty/TastyReader.scala
@@ -1,11 +1,9 @@
-package dotty.tools
-package dotc
-package core
-package tasty
+package dotty.tools.tasty
 
-import TastyBuffer._
 import collection.mutable
 
+import TastyBuffer._
+
 /** A byte array buffer that can be filled with bytes or natural numbers in TASTY format,
  *  and that supports reading and patching addresses represented as natural numbers.
  *
diff --git a/tasty/src/dotty/tools/tasty/UnpickleException.scala b/tasty/src/dotty/tools/tasty/UnpickleException.scala
new file mode 100644
index 000000000000..d1eb5f696ed4
--- /dev/null
+++ b/tasty/src/dotty/tools/tasty/UnpickleException.scala
@@ -0,0 +1,3 @@
+package dotty.tools.tasty
+
+class UnpickleException(msg: String) extends RuntimeException(msg)
diff --git a/tasty/src/dotty/tools/tasty/util/Util.scala b/tasty/src/dotty/tools/tasty/util/Util.scala
new file mode 100644
index 000000000000..5726e65773b0
--- /dev/null
+++ b/tasty/src/dotty/tools/tasty/util/Util.scala
@@ -0,0 +1,14 @@
+package dotty.tools.tasty.util
+
+import reflect.ClassTag
+
+object Util {
+
+  /** An array twice the size of given array, with existing elements copied over */
+  def dble[T: ClassTag](arr: Array[T]): Array[T] = {
+    val arr1 = new Array[T](arr.length * 2)
+    System.arraycopy(arr, 0, arr1, 0, arr.length)
+    arr1
+  }
+
+}