diff --git a/src/main/scala/gitbucket/core/api/AddACollaborator.scala b/src/main/scala/gitbucket/core/api/AddACollaborator.scala
new file mode 100644
index 0000000..05b1768
--- /dev/null
+++ b/src/main/scala/gitbucket/core/api/AddACollaborator.scala
@@ -0,0 +1,9 @@
+package gitbucket.core.api
+
+case class AddACollaborator(permission: String) {
+  val role: String = permission match {
+    case "admin" => "ADMIN"
+    case "push"  => "DEVELOPER"
+    case "pull"  => "GUEST"
+  }
+}
diff --git a/src/main/scala/gitbucket/core/api/ApiGroup.scala b/src/main/scala/gitbucket/core/api/ApiGroup.scala
new file mode 100644
index 0000000..5af6d4f
--- /dev/null
+++ b/src/main/scala/gitbucket/core/api/ApiGroup.scala
@@ -0,0 +1,20 @@
+package gitbucket.core.api
+
+import java.util.Date
+
+import gitbucket.core.model.Account
+
+case class ApiGroup(login: String, description: Option[String], created_at: Date) {
+  val id = 0 // dummy id
+  val url = ApiPath(s"/api/v3/orgs/${login}")
+  val html_url = ApiPath(s"/${login}")
+  val avatar_url = ApiPath(s"/${login}/_avatar")
+}
+
+object ApiGroup {
+  def apply(group: Account): ApiGroup = ApiGroup(
+    login = group.userName,
+    description = group.description,
+    created_at = group.registeredDate
+  )
+}
diff --git a/src/main/scala/gitbucket/core/api/CreateAUser.scala b/src/main/scala/gitbucket/core/api/CreateAUser.scala
new file mode 100644
index 0000000..f2cd9f0
--- /dev/null
+++ b/src/main/scala/gitbucket/core/api/CreateAUser.scala
@@ -0,0 +1,11 @@
+package gitbucket.core.api
+
+case class CreateAUser(
+  login: String,
+  password: String,
+  email: String,
+  fullName: Option[String],
+  isAdmin: Option[Boolean],
+  description: Option[String],
+  url: Option[String]
+)
diff --git a/src/main/scala/gitbucket/core/api/JsonFormat.scala b/src/main/scala/gitbucket/core/api/JsonFormat.scala
index 8579926..96fbd69 100644
--- a/src/main/scala/gitbucket/core/api/JsonFormat.scala
+++ b/src/main/scala/gitbucket/core/api/JsonFormat.scala
@@ -24,6 +24,7 @@
         }, { case x: Date => JString(OffsetDateTime.ofInstant(x.toInstant, ZoneId.of("UTC")).format(parserISO)) }
     )
   ) + FieldSerializer[ApiUser]() +
+    FieldSerializer[ApiGroup]() +
     FieldSerializer[ApiPullRequest]() +
     FieldSerializer[ApiRepository]() +
     FieldSerializer[ApiCommitListItem.Parent]() +
diff --git a/src/main/scala/gitbucket/core/controller/api/ApiIssueControllerBase.scala b/src/main/scala/gitbucket/core/controller/api/ApiIssueControllerBase.scala
index 6fe0632..12f44be 100644
--- a/src/main/scala/gitbucket/core/controller/api/ApiIssueControllerBase.scala
+++ b/src/main/scala/gitbucket/core/controller/api/ApiIssueControllerBase.scala
@@ -5,7 +5,7 @@
 import gitbucket.core.service.{AccountService, IssueCreationService, IssuesService, MilestonesService}
 import gitbucket.core.service.IssuesService.IssueSearchCondition
 import gitbucket.core.service.PullRequestService.PullRequestLimit
-import gitbucket.core.util.{ReadableUsersAuthenticator, ReferrerAuthenticator, RepositoryName}
+import gitbucket.core.util.{ReadableUsersAuthenticator, ReferrerAuthenticator, RepositoryName, UsersAuthenticator}
 import gitbucket.core.util.Implicits._
 
 trait ApiIssueControllerBase extends ControllerBase {
@@ -18,6 +18,7 @@
   /*
    * i. List issues
    * https://developer.github.com/v3/issues/#list-issues
+   * requested: 1743
    */
 
   /*
diff --git a/src/main/scala/gitbucket/core/controller/api/ApiOrganizationControllerBase.scala b/src/main/scala/gitbucket/core/controller/api/ApiOrganizationControllerBase.scala
index 0b64c9f..85ca93c 100644
--- a/src/main/scala/gitbucket/core/controller/api/ApiOrganizationControllerBase.scala
+++ b/src/main/scala/gitbucket/core/controller/api/ApiOrganizationControllerBase.scala
@@ -1,26 +1,36 @@
 package gitbucket.core.controller.api
-import gitbucket.core.api.{ApiRepository, ApiUser, JsonFormat}
+import gitbucket.core.api.{ApiGroup, ApiRepository, ApiUser, JsonFormat}
 import gitbucket.core.controller.ControllerBase
 import gitbucket.core.service.{AccountService, RepositoryService}
 import gitbucket.core.util.Implicits._
+import gitbucket.core.util.UsersAuthenticator
 
 trait ApiOrganizationControllerBase extends ControllerBase {
-  self: RepositoryService with AccountService =>
+  self: RepositoryService with AccountService with UsersAuthenticator =>
 
   /*
    * i. List your organizations
    * https://developer.github.com/v3/orgs/#list-your-organizations
    */
+  get("/api/v3/user/orgs")(usersOnly {
+    JsonFormat(getGroupsByUserName(context.loginAccount.get.userName).flatMap(getAccountByUserName(_)).map(ApiGroup(_)))
+  })
 
   /*
    * ii. List all organizations
    * https://developer.github.com/v3/orgs/#list-all-organizations
    */
+  get("/api/v3/organizations") {
+    JsonFormat(getAllUsers(false, true).filter(a => a.isGroupAccount).map(ApiGroup(_)))
+  }
 
   /*
    * iii. List user organizations
    * https://developer.github.com/v3/orgs/#list-user-organizations
    */
+  get("/api/v3/users/:userName/orgs") {
+    JsonFormat(getGroupsByUserName(params("userName")).flatMap(getAccountByUserName(_)).map(ApiGroup(_)))
+  }
 
   /**
    * iv. Get an organization
@@ -28,7 +38,26 @@
    */
   get("/api/v3/orgs/:groupName") {
     getAccountByUserName(params("groupName")).filter(account => account.isGroupAccount).map { account =>
-      JsonFormat(ApiUser(account))
+      JsonFormat(ApiGroup(account))
     } getOrElse NotFound()
   }
+
+  /*
+   * v. Edit an organization
+   * https://developer.github.com/v3/orgs/#edit-an-organization
+   */
+
+  /*
+   * ghe: i. Create an organization
+   * https://developer.github.com/enterprise/2.14/v3/enterprise-admin/orgs/#create-an-organization
+   */
+
+  /*
+   * ghe: ii. Rename an organization
+   * https://developer.github.com/enterprise/2.14/v3/enterprise-admin/orgs/#rename-an-organization
+   */
+
+  /*
+ * should implement delete an organization API?
+ */
 }
diff --git a/src/main/scala/gitbucket/core/controller/api/ApiPullRequestControllerBase.scala b/src/main/scala/gitbucket/core/controller/api/ApiPullRequestControllerBase.scala
index fe66183..d2d8357 100644
--- a/src/main/scala/gitbucket/core/controller/api/ApiPullRequestControllerBase.scala
+++ b/src/main/scala/gitbucket/core/controller/api/ApiPullRequestControllerBase.scala
@@ -100,6 +100,7 @@
   /*
    * iv. Create a pull request
    * https://developer.github.com/v3/pulls/#create-a-pull-request
+   * requested #1843
    */
 
   /*
diff --git a/src/main/scala/gitbucket/core/controller/api/ApiRepositoryCollaboratorControllerBase.scala b/src/main/scala/gitbucket/core/controller/api/ApiRepositoryCollaboratorControllerBase.scala
index 402b7a3..f8fe1e5 100644
--- a/src/main/scala/gitbucket/core/controller/api/ApiRepositoryCollaboratorControllerBase.scala
+++ b/src/main/scala/gitbucket/core/controller/api/ApiRepositoryCollaboratorControllerBase.scala
@@ -1,12 +1,13 @@
 package gitbucket.core.controller.api
-import gitbucket.core.api.{ApiUser, JsonFormat}
+import gitbucket.core.api.{AddACollaborator, ApiUser, JsonFormat}
 import gitbucket.core.controller.ControllerBase
 import gitbucket.core.service.{AccountService, RepositoryService}
 import gitbucket.core.util.Implicits._
-import gitbucket.core.util.ReferrerAuthenticator
+import gitbucket.core.util.{OwnerAuthenticator, ReferrerAuthenticator}
+import org.scalatra.NoContent
 
 trait ApiRepositoryCollaboratorControllerBase extends ControllerBase {
-  self: RepositoryService with AccountService with ReferrerAuthenticator =>
+  self: RepositoryService with AccountService with ReferrerAuthenticator with OwnerAuthenticator =>
 
   /*
    * i. List collaborators
@@ -31,10 +32,24 @@
   /*
    * iv. Add user as a collaborator
    * https://developer.github.com/v3/repos/collaborators/#add-user-as-a-collaborator
+   * requested #1586
    */
+  put("/api/v3/repos/:owner/:repository/collaborators/:userName")(ownerOnly { repository =>
+    for {
+      data <- extractFromJsonBody[AddACollaborator]
+    } yield {
+      addCollaborator(repository.owner, repository.name, params("userName"), data.role)
+      NoContent()
+    }
+  })
 
   /*
- * v. Remove user as a collaborator
- * https://developer.github.com/v3/repos/collaborators/#remove-user-as-a-collaborator
- */
+   * v. Remove user as a collaborator
+   * https://developer.github.com/v3/repos/collaborators/#remove-user-as-a-collaborator
+   * requested #1586
+   */
+  delete("/api/v3/repos/:owner/:repository/collaborators/:userName")(ownerOnly { repository =>
+    removeCollaborator(repository.owner, repository.name, params("userName"))
+    NoContent()
+  })
 }
diff --git a/src/main/scala/gitbucket/core/controller/api/ApiRepositoryContentsControllerBase.scala b/src/main/scala/gitbucket/core/controller/api/ApiRepositoryContentsControllerBase.scala
index c1d128b..d0dae95 100644
--- a/src/main/scala/gitbucket/core/controller/api/ApiRepositoryContentsControllerBase.scala
+++ b/src/main/scala/gitbucket/core/controller/api/ApiRepositoryContentsControllerBase.scala
@@ -103,16 +103,19 @@
   /*
    * iii. Create a file
    * https://developer.github.com/v3/repos/contents/#create-a-file
+   * requested #2112
    */
 
   /*
    * iv. Update a file
    * https://developer.github.com/v3/repos/contents/#update-a-file
+   * requested #2112
    */
 
   /*
    * v. Delete a file
    * https://developer.github.com/v3/repos/contents/#delete-a-file
+   * should be implemented
    */
 
   /*
diff --git a/src/main/scala/gitbucket/core/controller/api/ApiUserControllerBase.scala b/src/main/scala/gitbucket/core/controller/api/ApiUserControllerBase.scala
index 7c596fd..d5bbbd8 100644
--- a/src/main/scala/gitbucket/core/controller/api/ApiUserControllerBase.scala
+++ b/src/main/scala/gitbucket/core/controller/api/ApiUserControllerBase.scala
@@ -1,11 +1,12 @@
 package gitbucket.core.controller.api
-import gitbucket.core.api.{ApiUser, JsonFormat}
+import gitbucket.core.api.{ApiUser, CreateAUser, JsonFormat}
 import gitbucket.core.controller.ControllerBase
 import gitbucket.core.service.{AccountService, RepositoryService}
+import gitbucket.core.util.AdminAuthenticator
 import gitbucket.core.util.Implicits._
 
 trait ApiUserControllerBase extends ControllerBase {
-  self: RepositoryService with AccountService =>
+  self: RepositoryService with AccountService with AdminAuthenticator =>
 
   /**
    * i. Get a single user
@@ -39,8 +40,37 @@
    */
 
   /*
- * v. Get all users
- * https://developer.github.com/v3/users/#get-all-users
- */
+   * v. Get all users
+   * https://developer.github.com/v3/users/#get-all-users
+   */
 
+  /*
+   * ghe: i. Create a new use
+   * https://developer.github.com/enterprise/2.14/v3/enterprise-admin/users/#create-a-new-user
+   */
+  post("/api/v3/admin/users")(adminOnly {
+    for {
+      data <- extractFromJsonBody[CreateAUser]
+    } yield {
+      val user = createAccount(
+        data.login,
+        data.password,
+        data.fullName.getOrElse(data.login),
+        data.email,
+        data.isAdmin.getOrElse(false),
+        data.description,
+        data.url
+      )
+      JsonFormat(ApiUser(user))
+    }
+  })
+
+  /*
+   * ghe: vii. Suspend a user
+   * https://developer.github.com/enterprise/2.14/v3/enterprise-admin/users/#suspend-a-user
+   */
+  /*
+   * ghe: vii. Unsuspend a user
+   * https://developer.github.com/enterprise/2.14/v3/enterprise-admin/users/#unsuspend-a-user
+   */
 }
diff --git a/src/main/scala/gitbucket/core/service/AccountService.scala b/src/main/scala/gitbucket/core/service/AccountService.scala
index ea851b1..f5f9cdb 100644
--- a/src/main/scala/gitbucket/core/service/AccountService.scala
+++ b/src/main/scala/gitbucket/core/service/AccountService.scala
@@ -163,8 +163,8 @@
     isAdmin: Boolean,
     description: Option[String],
     url: Option[String]
-  )(implicit s: Session): Unit =
-    Accounts insert Account(
+  )(implicit s: Session): Account = {
+    val account = Account(
       userName = userName,
       password = password,
       fullName = fullName,
@@ -179,6 +179,9 @@
       isRemoved = false,
       description = description
     )
+    Accounts insert account
+    account
+  }
 
   def updateAccount(account: Account)(implicit s: Session): Unit =
     Accounts
diff --git a/src/main/scala/gitbucket/core/service/RepositoryService.scala b/src/main/scala/gitbucket/core/service/RepositoryService.scala
index 08f077d..e5295ed 100644
--- a/src/main/scala/gitbucket/core/service/RepositoryService.scala
+++ b/src/main/scala/gitbucket/core/service/RepositoryService.scala
@@ -561,6 +561,14 @@
     Collaborators insert Collaborator(userName, repositoryName, collaboratorName, role)
 
   /**
+   * Remove specified collaborator from the repository.
+   */
+  def removeCollaborator(userName: String, repositoryName: String, collaboratorName: String)(
+    implicit s: Session
+  ): Unit =
+    Collaborators.filter(_.byPrimaryKey(userName, repositoryName, collaboratorName)).delete
+
+  /**
    * Remove all collaborators from the repository.
    */
   def removeCollaborators(userName: String, repositoryName: String)(implicit s: Session): Unit =