diff --git a/internal/api/problem/search.go b/internal/api/problem/search.go
index 5a312dd..01bb9ef 100644
--- a/internal/api/problem/search.go
+++ b/internal/api/problem/search.go
@@ -7,7 +7,8 @@ import (
 )
 
 type searchRequest struct {
-	Search string `form:"search" json:"search"`
+	Keyword string `form:"keyword" json:"keyword"`
+	Tag     string `form:"tag" json:"tag"`
 }
 
 // Search
@@ -16,7 +17,8 @@ type searchRequest struct {
 // @Tags 	    problem
 // @Accept      application/x-www-form-urlencoded
 // @Produce     json
-// @Param       search formData string false "keyword"
+// @Param       keyword formData string false "keyword"
+// @Param       tag     formData string false "tag"
 // @Response    200 {object} e.Response[[]model.Problem] "problems found"
 // @Router      /v1/problem/search [post]
 func (h *handler) Search(c *gin.Context) {
@@ -27,13 +29,13 @@ func (h *handler) Search(c *gin.Context) {
 	}
 
 	// TODO: pagination
-	if req.Search == "" {
+	if req.Keyword == "" {
 		// TODO: query without LIKE
-		problems, status := h.problemService.QueryFuzz(req.Search, true, true)
+		problems, status := h.problemService.QueryFuzz(req.Keyword, req.Tag, true, true)
 		e.Pong(c, status, problems)
 		return
 	} else {
-		problems, status := h.problemService.QueryFuzz(req.Search, true, true)
+		problems, status := h.problemService.QueryFuzz(req.Keyword, req.Tag, true, true)
 		e.Pong(c, status, problems)
 		return
 	}
diff --git a/internal/api/problem/update.go b/internal/api/problem/update.go
index a45e9d4..4cb8f4c 100644
--- a/internal/api/problem/update.go
+++ b/internal/api/problem/update.go
@@ -6,13 +6,15 @@ import (
 	"git.0x7f.app/WOJ/woj-server/internal/service/problem"
 	"git.0x7f.app/WOJ/woj-server/pkg/utils"
 	"github.com/gin-gonic/gin"
+	"github.com/jackc/pgtype"
 )
 
 type updateRequest struct {
-	Pid       uint   `form:"pid"        json:"pid"`
-	Title     string `form:"title"      json:"title"`
-	Statement string `form:"statement"  json:"statement"`
-	IsEnabled bool   `form:"is_enabled" json:"is_enabled"`
+	Pid       uint     `form:"pid"        json:"pid"`
+	Title     string   `form:"title"      json:"title"`
+	Statement string   `form:"statement"  json:"statement"`
+	Tags      []string `form:"tags"       json:"tags"`
+	IsEnabled bool     `form:"is_enabled" json:"is_enabled"`
 }
 
 // Update
@@ -21,10 +23,11 @@ type updateRequest struct {
 // @Tags 	    problem,admin
 // @Accept      application/x-www-form-urlencoded
 // @Produce     json
-// @Param       pid          formData int    false "problem id, 0 for create"
-// @Param       title        formData string false "title"
-// @Param       statement    formData string false "statement"
-// @Param       is_enabled   formData bool   false "is enabled"
+// @Param       pid          formData int      false "problem id, 0 for create"
+// @Param       title        formData string   false "title"
+// @Param       statement    formData string   false "statement"
+// @Param       tags         formData []string false "tags"
+// @Param       is_enabled   formData bool     false "is enabled"
 // @Response    200 {object} e.Response[model.Problem] "problem info without provider information"
 // @Security    Authentication
 // @Router      /v1/problem/update [post]
@@ -60,6 +63,7 @@ func (h *handler) Update(c *gin.Context) {
 		createData := &problem.CreateData{
 			Title:      req.Title,
 			Statement:  req.Statement,
+			Tags:       req.Tags,
 			ProviderID: uid,
 			IsEnabled:  false,
 		}
@@ -83,6 +87,11 @@ func (h *handler) Update(c *gin.Context) {
 		// update problem
 		p.Title = utils.If(req.Title != "", req.Title, p.Title)
 		p.Statement = utils.If(req.Statement != "", req.Statement, p.Statement)
+		if len(req.Tags) != 0 {
+			tags := pgtype.TextArray{}
+			_ = tags.Set(req.Tags)
+			p.Tags = tags
+		}
 		p.IsEnabled = req.IsEnabled
 
 		p, status = h.problemService.Update(p)
diff --git a/internal/model/Problem.go b/internal/model/Problem.go
index c72b0b9..6f3d0e1 100644
--- a/internal/model/Problem.go
+++ b/internal/model/Problem.go
@@ -7,11 +7,12 @@ import (
 
 type Problem struct {
 	gorm.Model `json:"meta"`
-	Title      string `json:"title"      gorm:"not null"`
-	Statement  string `json:"statement"  gorm:"not null"`
-	ProviderID uint   `json:"-"          gorm:"not null;index"`
-	Provider   User   `json:"provider"   gorm:"foreignKey:ProviderID"`
-	IsEnabled  bool   `json:"is_enabled" gorm:"not null;index"`
+	Title      string           `json:"title"      gorm:"not null;index"`
+	Statement  string           `json:"statement"  gorm:"not null"`
+	Tags       pgtype.TextArray `json:"tags"       gorm:"type:text[];index"`
+	ProviderID uint             `json:"-"          gorm:"not null;index"`
+	Provider   User             `json:"provider"   gorm:"foreignKey:ProviderID"`
+	IsEnabled  bool             `json:"is_enabled" gorm:"not null;index"`
 }
 
 type ProblemVersion struct {
diff --git a/internal/service/problem/create.go b/internal/service/problem/create.go
index 41568e1..27e7c29 100644
--- a/internal/service/problem/create.go
+++ b/internal/service/problem/create.go
@@ -3,20 +3,25 @@ package problem
 import (
 	"git.0x7f.app/WOJ/woj-server/internal/e"
 	"git.0x7f.app/WOJ/woj-server/internal/model"
+	"github.com/jackc/pgtype"
 	"go.uber.org/zap"
 )
 
 type CreateData struct {
 	Title      string
 	Statement  string
+	Tags       []string
 	ProviderID uint
 	IsEnabled  bool
 }
 
 func (s *service) Create(data *CreateData) (*model.Problem, e.Status) {
+	tags := pgtype.TextArray{}
+	_ = tags.Set(data.Tags)
 	problem := &model.Problem{
 		Title:      data.Title,
 		Statement:  data.Statement,
+		Tags:       tags,
 		ProviderID: data.ProviderID,
 		IsEnabled:  data.IsEnabled,
 	}
diff --git a/internal/service/problem/createVersion.go b/internal/service/problem/create_version.go
similarity index 100%
rename from internal/service/problem/createVersion.go
rename to internal/service/problem/create_version.go
diff --git a/internal/service/problem/queryFuzz.go b/internal/service/problem/query_fuzz.go
similarity index 56%
rename from internal/service/problem/queryFuzz.go
rename to internal/service/problem/query_fuzz.go
index 20f0149..740b0ca 100644
--- a/internal/service/problem/queryFuzz.go
+++ b/internal/service/problem/query_fuzz.go
@@ -7,22 +7,28 @@ import (
 	"gorm.io/gorm/clause"
 )
 
-func (s *service) QueryFuzz(search string, associations bool, shouldEnable bool) ([]*model.Problem, e.Status) {
+func (s *service) QueryFuzz(keyword string, tag string, associations bool, shouldEnable bool) ([]*model.Problem, e.Status) {
 	problems := make([]*model.Problem, 0)
-
 	query := s.db.Get()
+
 	if associations {
 		query = query.Preload(clause.Associations)
 	}
 	if shouldEnable {
 		query = query.Where("is_enabled = true")
 	}
+
 	query = query.
-		Where(s.db.Get().Where("title LIKE ?", "%"+search+"%").
-			Or("statement LIKE ?", "%"+search+"%"))
+		Where(s.db.Get().Where("title LIKE ?", "%"+keyword+"%").
+			Or("statement LIKE ?", "%"+keyword+"%"))
+
+	if tag != "" {
+		query = query.Where("tags @> array[?]", tag)
+	}
+
 	err := query.Find(&problems).Error
 	if err != nil {
-		s.log.Warn("DatabaseError", zap.Error(err), zap.Any("search", search))
+		s.log.Warn("DatabaseError", zap.Error(err), zap.Any("keyword", keyword))
 		return nil, e.DatabaseError
 	}
 
diff --git a/internal/service/problem/queryLatestVersion.go b/internal/service/problem/query_latest_version.go
similarity index 100%
rename from internal/service/problem/queryLatestVersion.go
rename to internal/service/problem/query_latest_version.go
diff --git a/internal/service/problem/queryVersion.go b/internal/service/problem/query_version.go
similarity index 100%
rename from internal/service/problem/queryVersion.go
rename to internal/service/problem/query_version.go
diff --git a/internal/service/problem/service.go b/internal/service/problem/service.go
index f4be009..f3fb43e 100644
--- a/internal/service/problem/service.go
+++ b/internal/service/problem/service.go
@@ -15,7 +15,7 @@ type Service interface {
 	Create(data *CreateData) (*model.Problem, e.Status)
 	Update(problem *model.Problem) (*model.Problem, e.Status)
 	Query(pid uint, associations bool, shouldEnable bool) (*model.Problem, e.Status)
-	QueryFuzz(search string, associations bool, shouldEnable bool) ([]*model.Problem, e.Status)
+	QueryFuzz(keyword string, tag string, associations bool, shouldEnable bool) ([]*model.Problem, e.Status)
 
 	CreateVersion(data *CreateVersionData) (*model.ProblemVersion, e.Status)
 	UpdateVersion(pvid uint, values interface{}) e.Status
diff --git a/internal/service/problem/updateVersion.go b/internal/service/problem/update_version.go
similarity index 100%
rename from internal/service/problem/updateVersion.go
rename to internal/service/problem/update_version.go