diff --git a/github4s/src/main/scala/github4s/Decoders.scala b/github4s/src/main/scala/github4s/Decoders.scala
index 7b720612..671d933f 100644
--- a/github4s/src/main/scala/github4s/Decoders.scala
+++ b/github4s/src/main/scala/github4s/Decoders.scala
@@ -18,6 +18,7 @@ package github4s
 
 import cats.data.NonEmptyList
 import cats.syntax.all._
+import github4s.domain.RepoUrlKeys.{CommitComparisonResponse, FileComparison}
 import github4s.domain._
 import io.circe.Decoder.Result
 import io.circe._
@@ -241,6 +242,8 @@ object Decoders {
         )
       )
 
+  implicit val decoderFileComparison: Decoder[FileComparison] = deriveDecoder[FileComparison]
+
   implicit val decoderCreatePullRequestData: Decoder[CreatePullRequestData] =
     deriveDecoder[CreatePullRequestData]
   implicit val decoderCreatePullRequestIssue: Decoder[CreatePullRequestIssue] =
@@ -265,6 +268,8 @@ object Decoders {
   implicit val decoderNewTagRequest: Decoder[NewTagRequest]       = deriveDecoder[NewTagRequest]
   implicit val decoderNewTreeRequest: Decoder[NewTreeRequest]     = deriveDecoder[NewTreeRequest]
   implicit val decoderNewCommitRequest: Decoder[NewCommitRequest] = deriveDecoder[NewCommitRequest]
+  implicit val decoderBranchUpdateRequest: Decoder[BranchUpdateRequest] =
+    deriveDecoder[BranchUpdateRequest]
 
   implicit def decodeNonEmptyList[T](implicit D: Decoder[T]): Decoder[NonEmptyList[T]] = {
 
@@ -367,4 +372,9 @@ object Decoders {
   implicit val decoderEditGistRequest: Decoder[EditGistRequest]   = deriveDecoder[EditGistRequest]
   implicit val decoderEditIssueRequest: Decoder[EditIssueRequest] = deriveDecoder[EditIssueRequest]
   implicit val decoderMilestoneData: Decoder[MilestoneData]       = deriveDecoder[MilestoneData]
+
+  implicit val decodeBranchUpdateResponse: Decoder[BranchUpdateResponse] =
+    deriveDecoder[BranchUpdateResponse]
+  implicit val decodeCommitComparisonResponse: Decoder[CommitComparisonResponse] =
+    deriveDecoder[CommitComparisonResponse]
 }
diff --git a/github4s/src/main/scala/github4s/Encoders.scala b/github4s/src/main/scala/github4s/Encoders.scala
index 7d7dbaae..4392b96f 100644
--- a/github4s/src/main/scala/github4s/Encoders.scala
+++ b/github4s/src/main/scala/github4s/Encoders.scala
@@ -16,6 +16,7 @@
 
 package github4s
 
+import github4s.domain.RepoUrlKeys.{CommitComparisonResponse, FileComparison}
 import github4s.domain._
 import io.circe._
 import io.circe.generic.semiauto.deriveEncoder
@@ -182,6 +183,9 @@ object Encoders {
     deriveEncoder[NewReleaseRequest]
   implicit val encoderNewStatusRequest: Encoder[NewStatusRequest] = deriveEncoder[NewStatusRequest]
   implicit val encoderMilestoneData: Encoder[MilestoneData]       = deriveEncoder[MilestoneData]
+  implicit val encodeBranchUpdateRequest: Encoder[BranchUpdateRequest] =
+    deriveEncoder[BranchUpdateRequest]
+
   implicit val encoderCreateReviewComment: Encoder[CreateReviewComment] =
     deriveEncoder[CreateReviewComment]
   implicit val encodeNewPullRequestReview: Encoder[CreatePRReviewRequest] =
@@ -237,4 +241,9 @@ object Encoders {
   implicit val encoderUser: Encoder[User]                         = deriveEncoder[User]
   implicit val encoderComment: Encoder[Comment]                   = deriveEncoder[Comment]
   implicit val encoderMilestone: Encoder[Milestone]               = deriveEncoder[Milestone]
+  implicit val encodeBranchUpdateResponse: Encoder[BranchUpdateResponse] =
+    deriveEncoder[BranchUpdateResponse]
+  implicit val encodeFileComparison: Encoder[FileComparison] = deriveEncoder[FileComparison]
+  implicit val encodeCommitComparisonResponse: Encoder[CommitComparisonResponse] =
+    deriveEncoder[CommitComparisonResponse]
 }
diff --git a/github4s/src/main/scala/github4s/algebras/PullRequests.scala b/github4s/src/main/scala/github4s/algebras/PullRequests.scala
index fae833f8..f75d9b20 100644
--- a/github4s/src/main/scala/github4s/algebras/PullRequests.scala
+++ b/github4s/src/main/scala/github4s/algebras/PullRequests.scala
@@ -179,4 +179,15 @@ trait PullRequests[F[_]] {
       reviewers: ReviewersRequest,
       headers: Map[String, String] = Map()
   ): F[GHResponse[PullRequest]]
+
+  /**
+   * This is an experimental API and could be changed or removed
+   */
+  def updateBranch(
+      owner: String,
+      repo: String,
+      pullRequest: Int,
+      expectedHeadSha: Option[String] = None,
+      headers: Map[String, String] = Map()
+  ): F[GHResponse[BranchUpdateResponse]]
 }
diff --git a/github4s/src/main/scala/github4s/algebras/Repositories.scala b/github4s/src/main/scala/github4s/algebras/Repositories.scala
index aa6e3c6f..0d5fe64e 100644
--- a/github4s/src/main/scala/github4s/algebras/Repositories.scala
+++ b/github4s/src/main/scala/github4s/algebras/Repositories.scala
@@ -18,6 +18,7 @@ package github4s.algebras
 
 import cats.data.NonEmptyList
 import github4s.GHResponse
+import github4s.domain.RepoUrlKeys.CommitComparisonResponse
 import github4s.domain._
 
 trait Repositories[F[_]] {
@@ -228,6 +229,24 @@ trait Repositories[F[_]] {
       headers: Map[String, String] = Map()
   ): F[GHResponse[List[Commit]]]
 
+  /**
+   * Compare any two commits in the same repository
+   *
+   * @param owner of the repo
+   * @param repo name of the repo
+   * @param commitSha commit to compare against base
+   * @param baseSha the base to compare against
+   * @param headers optional user headers to include in the request
+   * @return GhResponse[CommitComparisonResponse] comparison result
+   */
+  def compareCommits(
+      owner: String,
+      repo: String,
+      commitSha: String,
+      baseSha: String,
+      headers: Map[String, String] = Map()
+  ): F[GHResponse[CommitComparisonResponse]]
+
   /**
    * Retrieve list of branches for a repo
    *
diff --git a/github4s/src/main/scala/github4s/domain/PullRequest.scala b/github4s/src/main/scala/github4s/domain/PullRequest.scala
index a8a2ae3f..aa87d49c 100644
--- a/github4s/src/main/scala/github4s/domain/PullRequest.scala
+++ b/github4s/src/main/scala/github4s/domain/PullRequest.scala
@@ -151,3 +151,6 @@ final case class ReviewersResponse(
     users: List[User],
     teams: List[Team]
 )
+
+final case class BranchUpdateRequest(expected_head_sha: Option[String])
+final case class BranchUpdateResponse(message: String, url: String)
diff --git a/github4s/src/main/scala/github4s/domain/Repository.scala b/github4s/src/main/scala/github4s/domain/Repository.scala
index 8d1dbe37..114f3936 100644
--- a/github4s/src/main/scala/github4s/domain/Repository.scala
+++ b/github4s/src/main/scala/github4s/domain/Repository.scala
@@ -349,4 +349,33 @@ object RepoUrlKeys {
     deployments_url
   )
 
+  final case class CommitComparisonResponse(
+      status: String,
+      ahead_by: Int,
+      behind_by: Int,
+      total_commits: Int,
+      url: Option[String] = None,
+      html_url: Option[String] = None,
+      permalink_url: Option[String] = None,
+      diff_url: Option[String] = None,
+      patch_url: Option[String] = None,
+      base_commit: Option[Commit] = None,
+      merge_base_commit: Option[Commit] = None,
+      commits: Seq[Commit] = Seq.empty,
+      files: Seq[FileComparison] = Seq.empty
+  )
+
+  final case class FileComparison(
+      sha: String,
+      filename: String,
+      status: String,
+      additions: Int,
+      deletions: Int,
+      changes: Int,
+      blob_url: String,
+      raw_url: String,
+      contents_url: String,
+      patch: String
+  )
+
 }
diff --git a/github4s/src/main/scala/github4s/interpreters/PullRequestsInterpreter.scala b/github4s/src/main/scala/github4s/interpreters/PullRequestsInterpreter.scala
index 55475b90..6535fafc 100644
--- a/github4s/src/main/scala/github4s/interpreters/PullRequestsInterpreter.scala
+++ b/github4s/src/main/scala/github4s/interpreters/PullRequestsInterpreter.scala
@@ -160,4 +160,17 @@ class PullRequestsInterpreter[F[_]](implicit client: HttpClient[F]) extends Pull
       headers,
       reviewers
     )
+
+  override def updateBranch(
+      owner: String,
+      repo: String,
+      pullRequest: Int,
+      expectedHeadSha: Option[String] = None,
+      headers: Map[String, String] = Map()
+  ): F[GHResponse[BranchUpdateResponse]] =
+    client.put[BranchUpdateRequest, BranchUpdateResponse](
+      s"repos/$owner/$repo/pulls/$pullRequest/update-branch",
+      headers ++ Seq("Accept" -> "application/vnd.github.lydian-preview+json"),
+      BranchUpdateRequest(expectedHeadSha)
+    )
 }
diff --git a/github4s/src/main/scala/github4s/interpreters/RepositoriesInterpreter.scala b/github4s/src/main/scala/github4s/interpreters/RepositoriesInterpreter.scala
index 39cd21fa..3afd7b30 100644
--- a/github4s/src/main/scala/github4s/interpreters/RepositoriesInterpreter.scala
+++ b/github4s/src/main/scala/github4s/interpreters/RepositoriesInterpreter.scala
@@ -19,13 +19,14 @@ package github4s.interpreters
 import cats.Functor
 import cats.data.NonEmptyList
 import cats.syntax.functor._
-import github4s.internal.Base64._
 import github4s.Decoders._
 import github4s.Encoders._
 import github4s.GHResponse
 import github4s.algebras.Repositories
+import github4s.domain.RepoUrlKeys.CommitComparisonResponse
 import github4s.domain._
 import github4s.http.HttpClient
+import github4s.internal.Base64._
 
 class RepositoriesInterpreter[F[_]: Functor](implicit
     client: HttpClient[F]
@@ -169,6 +170,18 @@ class RepositoriesInterpreter[F[_]: Functor](implicit
       pagination
     )
 
+  override def compareCommits(
+      owner: String,
+      repo: String,
+      commitSha: String,
+      baseSha: String,
+      headers: Map[String, String] = Map()
+  ): F[GHResponse[CommitComparisonResponse]] =
+    client.get[CommitComparisonResponse](
+      s"repos/$owner/$repo/compare/$baseSha...$commitSha",
+      headers
+    )
+
   override def listBranches(
       owner: String,
       repo: String,
@@ -344,5 +357,4 @@ class RepositoriesInterpreter[F[_]: Functor](implicit
         response.copy(result = Right(false))
       case Left(error) => GHResponse(Left(error), response.statusCode, response.headers)
     }
-
 }
diff --git a/github4s/src/test/scala-2/github4s/unit/EncoderDecoderSpec.scala b/github4s/src/test/scala-2/github4s/unit/EncoderDecoderSpec.scala
index e3cf6379..45157606 100644
--- a/github4s/src/test/scala-2/github4s/unit/EncoderDecoderSpec.scala
+++ b/github4s/src/test/scala-2/github4s/unit/EncoderDecoderSpec.scala
@@ -5,6 +5,7 @@ import com.eed3si9n.expecty.Expecty
 import github4s.ArbitraryDerivation
 import github4s.Decoders._
 import github4s.Encoders._
+import github4s.domain.RepoUrlKeys.CommitComparisonResponse
 import github4s.domain._
 import io.circe.{Decoder, Encoder, Printer}
 import org.scalacheck.fortyseven.GenInstances._
@@ -133,6 +134,9 @@ class EncoderDecoderSpec extends AnyFlatSpec with ScalaCheckPropertyChecks {
   test[Repository]
   test[ReviewersRequest]
   test[ReviewersResponse]
+  test[BranchUpdateRequest]
+  test[BranchUpdateResponse]
+  test[CommitComparisonResponse]
   test[SearchIssuesResult]
   test[SearchReposResult]
   test[Stargazer]
diff --git a/github4s/src/test/scala/github4s/integration/PullRequestsSpec.scala b/github4s/src/test/scala/github4s/integration/PullRequestsSpec.scala
index 3673340b..e637d0d1 100644
--- a/github4s/src/test/scala/github4s/integration/PullRequestsSpec.scala
+++ b/github4s/src/test/scala/github4s/integration/PullRequestsSpec.scala
@@ -356,4 +356,21 @@ trait PullRequestsSpec extends BaseIntegrationSpec {
     )
     removeReviewersResponse.statusCode shouldBe okStatusCode
   }
+
+  "PullRequests >> Update Branch" should "merge target branch's head into selected" taggedAs Integration in {
+    val response = clientResource
+      .use { client =>
+        Github[IO](client, accessToken).pullRequests
+          .updateBranch(
+            validRepoOwner,
+            validRepoName,
+            validPullRequestNumber,
+            headers = headerUserAgent
+          )
+      }
+      .unsafeRunSync()
+
+    testIsRight[BranchUpdateResponse](response)
+    response.statusCode shouldBe okStatusCode
+  }
 }
diff --git a/github4s/src/test/scala/github4s/integration/ReposSpec.scala b/github4s/src/test/scala/github4s/integration/ReposSpec.scala
index 9c5af34b..0abe9cdb 100644
--- a/github4s/src/test/scala/github4s/integration/ReposSpec.scala
+++ b/github4s/src/test/scala/github4s/integration/ReposSpec.scala
@@ -20,6 +20,7 @@ import cats.data.NonEmptyList
 import cats.effect.{IO, Resource}
 import cats.implicits._
 import github4s.GHError.{NotFoundError, UnauthorizedError}
+import github4s.domain.RepoUrlKeys.CommitComparisonResponse
 import github4s.domain._
 import github4s.utils.{BaseIntegrationSpec, Integration}
 import github4s.{GHResponse, Github}
@@ -471,6 +472,24 @@ trait ReposSpec extends BaseIntegrationSpec {
     response.statusCode shouldBe okStatusCode
   }
 
+  "Repos >> Compare" should "compare against the base" taggedAs Integration in {
+    val response = clientResource
+      .use { client =>
+        Github[IO](client, accessToken).repos
+          .compareCommits(validRepoOwner, validRepoName, validCommitSha, validBase)
+      }
+      .unsafeRunSync()
+
+    testIsRight[CommitComparisonResponse](
+      response,
+      { r =>
+        r.status shouldBe "behind"
+        r.behind_by should be > 0
+      }
+    )
+    response.statusCode shouldBe okStatusCode
+  }
+
   it should "successfully return results when a valid repo is provided using <owner>/<name> syntax" taggedAs Integration in {
     val response = clientResource
       .use { client =>
diff --git a/github4s/src/test/scala/github4s/unit/PullRequestsSpec.scala b/github4s/src/test/scala/github4s/unit/PullRequestsSpec.scala
index af95dd2c..2b3d2ab5 100644
--- a/github4s/src/test/scala/github4s/unit/PullRequestsSpec.scala
+++ b/github4s/src/test/scala/github4s/unit/PullRequestsSpec.scala
@@ -261,4 +261,25 @@ class PullRequestsSpec extends BaseSpec {
       .shouldNotFail
   }
 
+  "PullRequests.updateBranch" should "call to httpClient.put with the right parameters" in {
+
+    implicit val httpClientMock: HttpClient[IO] =
+      httpClientMockPut[BranchUpdateRequest, BranchUpdateResponse](
+        url = s"repos/$validRepoOwner/$validRepoName/pulls/$validPullRequestNumber/update-branch",
+        req = BranchUpdateRequest(None),
+        response = IO.pure(validBranchUpdateResponse)
+      )
+
+    val pullRequests = new PullRequestsInterpreter[IO]
+
+    pullRequests
+      .updateBranch(
+        validRepoOwner,
+        validRepoName,
+        validPullRequestNumber,
+        None,
+        headerUserAgent
+      )
+      .shouldNotFail
+  }
 }
diff --git a/github4s/src/test/scala/github4s/unit/ReposSpec.scala b/github4s/src/test/scala/github4s/unit/ReposSpec.scala
index 1b7abdd5..ad04d515 100644
--- a/github4s/src/test/scala/github4s/unit/ReposSpec.scala
+++ b/github4s/src/test/scala/github4s/unit/ReposSpec.scala
@@ -20,6 +20,7 @@ import cats.data.NonEmptyList
 import cats.effect.IO
 import github4s.Decoders._
 import github4s.Encoders._
+import github4s.domain.RepoUrlKeys.CommitComparisonResponse
 import github4s.domain._
 import github4s.http.HttpClient
 import github4s.internal.Base64._
@@ -434,4 +435,25 @@ class ReposSpec extends BaseSpec {
 
     repos.searchRepos("", validSearchParams, None, headerUserAgent).shouldNotFail
   }
+
+  "Repos.compare" should "call to httpClient.get with the right parameters" in {
+
+    implicit val httpClientMock: HttpClient[IO] = httpClientMockGet[CommitComparisonResponse](
+      url = s"repos/$validRepoOwner/$validRepoName/compare/$validCommitSha...$validMergeCommitSha",
+      response = IO.pure(validCommitComparisonResponse)
+    )
+
+    val repos = new RepositoriesInterpreter[IO]
+
+    repos
+      .compareCommits(
+        validRepoOwner,
+        validRepoName,
+        validCommitSha,
+        validMergeCommitSha,
+        headerUserAgent
+      )
+      .shouldNotFail
+  }
+
 }
diff --git a/github4s/src/test/scala/github4s/utils/TestData.scala b/github4s/src/test/scala/github4s/utils/TestData.scala
index 8ea9a4a1..309e2e1d 100644
--- a/github4s/src/test/scala/github4s/utils/TestData.scala
+++ b/github4s/src/test/scala/github4s/utils/TestData.scala
@@ -16,8 +16,9 @@
 
 package github4s.utils
 
-import java.util.UUID
+import github4s.domain.RepoUrlKeys.CommitComparisonResponse
 
+import java.util.UUID
 import github4s.internal.Base64._
 import github4s.domain._
 
@@ -489,6 +490,14 @@ trait TestData {
   val validRequestedReviewersResponse =
     ReviewersResponse(List(user), List(team))
 
+  val validBranchUpdateResponse =
+    BranchUpdateResponse(
+      "Updating pull request branch.",
+      s"https://github.com/repos/$validRepoOwner/$validRepoName/pulls/$validPullRequestNumber"
+    )
+
+  val validCommitComparisonResponse = CommitComparisonResponse("behind", 1, 2, 100)
+
   val validProjectId   = 4115271L
   val invalidProjectId = 11111L
 
diff --git a/microsite/docs/pull_request.md b/microsite/docs/pull_request.md
index 5229502d..a1ab80b8 100644
--- a/microsite/docs/pull_request.md
+++ b/microsite/docs/pull_request.md
@@ -14,6 +14,7 @@ with Github4s, you can interact with:
   - [List pull requests](#list-pull-requests)
   - [List the files in a pull request](#list-the-files-in-a-pull-request)
   - [Create a pull request](#create-a-pull-request)
+  - [Update branch](#update-a-pull-request-branch)
 - [Reviews](#reviews)
   - [List reviews](#list-pull-request-reviews)
   - [Get a review](#get-an-individual-review)
@@ -158,6 +159,32 @@ createPullRequestIssue.flatMap(_.result match {
 
 See [the API doc](https://developer.github.com/v3/pulls/#create-a-pull-request) for full reference.
 
+### Update a pull request branch
+
+Merges the base HEAD into your pull request branch. 
+Note that this is an experimental API, meaning github could stop supporting it at any time or change in an incompatible way. 
+
+Accepts these parameters:
+
+ - the repository coordinates (`owner` and `name` of the repository).
+ - `pullRequest`: integer id of you pr.
+ - `expectedHeadSha`: The expected SHA of the pull request's HEAD ref for an optional check on github's side.
+
+```scala mdoc:compile-only
+import github4s.domain.BranchUpdateResponse
+
+val updatePullRequestBranch = gh.pullRequests.updateBranch(
+  "47deg",
+  "github4s",
+  567)  
+updatePullRequestBranch.flatMap(_.result match {
+  case Left(e)  => IO.println(s"Something went wrong: ${e.getMessage}")
+  case Right(r) => IO.println(r)
+})
+```
+
+See [the API doc](https://developer.github.com/v3/pulls/#update-a-pull-request-branch) for full reference.
+
 ## Reviews
 
 ### List pull request reviews
diff --git a/microsite/docs/repository.md b/microsite/docs/repository.md
index 311bef2f..3be972e5 100644
--- a/microsite/docs/repository.md
+++ b/microsite/docs/repository.md
@@ -20,6 +20,7 @@ with Github4s, you can interact with:
   - [Get repository permissions for a user](#get-repository-permissions-for-a-user)
 - [Commits](#commits)
   - [List commits on a repository](#list-commits-on-a-repository)
+  - [Compare commits on a repository](#compare-commits-on-a-repository)
 - [Contents](#contents)
   - [Get contents](#get-contents)
   - [Create a File](#create-a-file)
@@ -263,6 +264,34 @@ The `result` on the right is the corresponding [List[Commit]][repository-scala].
 See [the API doc](https://developer.github.com/v3/repos/commits/#list-commits-on-a-repository) for full
 reference.
 
+### Compare commits on a repository
+
+You can compare two commits using `compareCommits`, it takes as arguments:
+
+- the repository coordinates (`owner` and `name` of the repository).
+- `commitSha` or branch to identify the commit you want to check.
+- `baseSha`: or branch you're comparing the commitSha against
+
+To compare commits:
+
+```scala mdoc:compile-only
+val compareCommits =
+  gh.repos.compareCommits(
+  "47deg",
+  "github4s",
+  "d3b048c1f500ee5450e5d7b3d1921ed3e7645891",
+  "main")
+compareCommits.flatMap(_.result match {
+  case Left(e)  => IO.println(s"Something went wrong: ${e.getMessage}")
+  case Right(r) => IO.println(r)
+})
+```
+
+The `result` on the right is the corresponding [List[CommitComparisonResponse]][repository-scala].
+
+See [the API doc](https://developer.github.com/v3/repos/#compare-two-commits) for full
+reference.
+
 ## Branches
 
 ### List branches on a repository