diff --git a/.circleci/config.yml b/.circleci/config.yml
index b00a076736..53ecc6dd51 100644
--- a/.circleci/config.yml
+++ b/.circleci/config.yml
@@ -109,6 +109,23 @@ jobs:
             make app-layers
             if [[ -n $(git status --porcelain) ]]; then echo "Please update the app layers using make app-layers"; exit 1; fi
 
+  build-api-spec:
+    docker:
+      - image: circleci/node:lts
+    working_directory: ~/mattermost
+    steps:
+      - attach_workspace:
+          at: ~/mattermost/
+      - run:
+          command: |
+            git clone https://github.com/mattermost/mattermost-api-reference.git
+            cd mattermost-api-reference
+            make build
+      - persist_to_workspace:
+          root: ~/mattermost
+          paths:
+            - mattermost-api-reference
+
   build:
     docker:
       - image: mattermost/mattermost-build-server:20200322_golang-1.14.1
@@ -127,7 +144,7 @@ jobs:
             export PATH=$PATH:$GOBIN
             cd mattermost-server
             make config-reset
-            make check-style BUILD_NUMBER='${CIRCLE_BRANCH}-${CIRCLE_BUILD_NUM}' MM_NO_ENTERPRISE_LINT=true
+            make check-style BUILD_NUMBER='${CIRCLE_BRANCH}-${CIRCLE_BUILD_NUM}' MM_NO_ENTERPRISE_LINT=true MM_VET_OPENSPEC_PATH='${PWD}/../mattermost-api-reference/v4/html/static/mattermost-openapi-v4.yaml'
             make build BUILD_NUMBER='${CIRCLE_BRANCH}-${CIRCLE_BUILD_NUM}'
             make package BUILD_NUMBER='${CIRCLE_BRANCH}-${CIRCLE_BUILD_NUM}'
       - store_artifacts:
@@ -389,9 +406,13 @@ workflows:
       - check-app-layers:
           requires:
             - setup
+      - build-api-spec:
+          requires:
+            - setup
       - build:
           requires:
             - check-app-layers
+            - build-api-spec
       - upload-s3-sha:
           context: mattermost-ci-pr-builds-s3
           requires:
diff --git a/Makefile b/Makefile
index 44007ae7ca..685d4ff5c0 100644
--- a/Makefile
+++ b/Makefile
@@ -517,9 +517,14 @@ vet: ## Run mattermost go vet specific checks
 	@if ! [ -x "$$(command -v $(GOBIN)/mattermost-govet)" ]; then \
 		echo "mattermost-govet is not installed. Please install it executing \"GO111MODULE=off GOBIN=$(PWD)/bin go get -u github.com/mattermost/mattermost-govet\""; \
 		exit 1; \
+	fi;
+	@VET_CMD="-license -structuredLogging -inconsistentReceiverName -tFatal"; \
+	if ! [ -z "${MM_VET_OPENSPEC_PATH}" ] && [ -f "${MM_VET_OPENSPEC_PATH}" ]; then \
+		VET_CMD="$$VET_CMD -openApiSync -openApiSync.spec=$$MM_VET_OPENSPEC_PATH"; \
+	else \
+		echo "MM_VET_OPENSPEC_PATH not set or spec yaml path in it is incorrect. Skipping API check"; \
 	fi; \
-
-	$(GO) vet -vettool=$(GOBIN)/mattermost-govet -license -structuredLogging -inconsistentReceiverName -tFatal ./...
+	$(GO) vet -vettool=$(GOBIN)/mattermost-govet $$VET_CMD ./...
 ifeq ($(BUILD_ENTERPRISE_READY),true)
 ifneq ($(MM_NO_ENTERPRISE_LINT),true)
 	$(GO) vet -vettool=$(GOBIN)/mattermost-govet -enterpriseLicense -structuredLogging -tFatal ./enterprise/...
diff --git a/api4/api.go b/api4/api.go
index 20748c5ce6..26acf42383 100644
--- a/api4/api.go
+++ b/api4/api.go
@@ -21,8 +21,8 @@ type Routes struct {
 
 	Users          *mux.Router // 'api/v4/users'
 	User           *mux.Router // 'api/v4/users/{user_id:[A-Za-z0-9]+}'
-	UserByUsername *mux.Router // 'api/v4/users/username/{username:[A-Za-z0-9_-\.]+}'
-	UserByEmail    *mux.Router // 'api/v4/users/email/{email}'
+	UserByUsername *mux.Router // 'api/v4/users/username/{username:[A-Za-z0-9\\_\\-\\.]+}'
+	UserByEmail    *mux.Router // 'api/v4/users/email/{email:.+}'
 
 	Bots *mux.Router // 'api/v4/bots'
 	Bot  *mux.Router // 'api/v4/bots/{bot_user_id:[A-Za-z0-9]+}'
@@ -32,8 +32,8 @@ type Routes struct {
 	Team               *mux.Router // 'api/v4/teams/{team_id:[A-Za-z0-9]+}'
 	TeamForUser        *mux.Router // 'api/v4/users/{user_id:[A-Za-z0-9]+}/teams/{team_id:[A-Za-z0-9]+}'
 	TeamByName         *mux.Router // 'api/v4/teams/name/{team_name:[A-Za-z0-9_-]+}'
-	TeamMembers        *mux.Router // 'api/v4/teams/{team_id:[A-Za-z0-9_-]+}/members'
-	TeamMember         *mux.Router // 'api/v4/teams/{team_id:[A-Za-z0-9_-]+}/members/{user_id:[A-Za-z0-9_-]+}'
+	TeamMembers        *mux.Router // 'api/v4/teams/{team_id:[A-Za-z0-9]+}/members'
+	TeamMember         *mux.Router // 'api/v4/teams/{team_id:[A-Za-z0-9]+}/members/{user_id:[A-Za-z0-9]+}'
 	TeamMembersForUser *mux.Router // 'api/v4/users/{user_id:[A-Za-z0-9]+}/teams/members'
 
 	Channels                 *mux.Router // 'api/v4/channels'
@@ -57,9 +57,9 @@ type Routes struct {
 	File  *mux.Router // 'api/v4/files/{file_id:[A-Za-z0-9]+}'
 
 	Plugins *mux.Router // 'api/v4/plugins'
-	Plugin  *mux.Router // 'api/v4/plugins/{plugin_id:[A-Za-z0-9_-]+}'
+	Plugin  *mux.Router // 'api/v4/plugins/{plugin_id:[A-Za-z0-9\\_\\-\\.]+}'
 
-	PublicFile *mux.Router // 'files/{file_id:[A-Za-z0-9]+}/public'
+	PublicFile *mux.Router // '/files/{file_id:[A-Za-z0-9]+}/public'
 
 	Commands *mux.Router // 'api/v4/commands'
 	Command  *mux.Router // 'api/v4/commands/{command_id:[A-Za-z0-9]+}'
@@ -107,11 +107,11 @@ type Routes struct {
 
 	Emojis      *mux.Router // 'api/v4/emoji'
 	Emoji       *mux.Router // 'api/v4/emoji/{emoji_id:[A-Za-z0-9]+}'
-	EmojiByName *mux.Router // 'api/v4/emoji/name/{emoji_name:[A-Za-z0-9_-\.]+}'
+	EmojiByName *mux.Router // 'api/v4/emoji/name/{emoji_name:[A-Za-z0-9\\_\\-\\+]+}'
 
-	ReactionByNameForPostForUser *mux.Router // 'api/v4/users/{user_id:[A-Za-z0-9]+}/posts/{post_id:[A-Za-z0-9]+}/reactions/{emoji_name:[A-Za-z0-9_-+]+}'
+	ReactionByNameForPostForUser *mux.Router // 'api/v4/users/{user_id:[A-Za-z0-9]+}/posts/{post_id:[A-Za-z0-9]+}/reactions/{emoji_name:[A-Za-z0-9\\_\\-\\+]+}'
 
-	TermsOfService *mux.Router // 'api/v4/terms_of_service
+	TermsOfService *mux.Router // 'api/v4/terms_of_service'
 	Groups         *mux.Router // 'api/v4/groups'
 }