diff --git a/optuna_dashboard/ts/action.ts b/optuna_dashboard/ts/action.ts
index dfe28f44..4db8c0b9 100644
--- a/optuna_dashboard/ts/action.ts
+++ b/optuna_dashboard/ts/action.ts
@@ -42,7 +42,7 @@ import {
   StudyDetails,
   StudySummary,
   Trial,
-} from "./types"
+} from "./types/optuna"
 
 // eslint-disable-next-line @typescript-eslint/explicit-module-boundary-types
 export const actionCreator = () => {
diff --git a/optuna_dashboard/ts/apiClient.ts b/optuna_dashboard/ts/apiClient.ts
index 6df9d1ff..ba5878cd 100644
--- a/optuna_dashboard/ts/apiClient.ts
+++ b/optuna_dashboard/ts/apiClient.ts
@@ -2,7 +2,6 @@ import * as plotly from "plotly.js-dist-min"
 import axios from "axios"
 import * as Optuna from "@optuna/types"
 import {
-  API_ENDPOINT,
   Artifact,
   FeedbackComponentType,
   FormWidgets,
@@ -16,7 +15,7 @@ import {
   StudySummary,
   Trial,
   TrialParam,
-} from "./types"
+} from "./types/optuna"
 
 const axiosInstance = axios.create({ baseURL: API_ENDPOINT })
 
diff --git a/optuna_dashboard/ts/components/App.tsx b/optuna_dashboard/ts/components/App.tsx
index 090f78c0..4459ff93 100644
--- a/optuna_dashboard/ts/components/App.tsx
+++ b/optuna_dashboard/ts/components/App.tsx
@@ -16,7 +16,6 @@ import { CompareStudies } from "./CompareStudies"
 import { StudyDetail } from "./StudyDetail"
 import { StudyList } from "./StudyList"
 import { QueryClient, QueryClientProvider } from "@tanstack/react-query"
-import { URL_PREFIX } from "ts/types"
 
 const queryClient = new QueryClient({
   defaultOptions: {
diff --git a/optuna_dashboard/ts/components/AppDrawer.tsx b/optuna_dashboard/ts/components/AppDrawer.tsx
index 551a5137..f0a31c8b 100644
--- a/optuna_dashboard/ts/components/AppDrawer.tsx
+++ b/optuna_dashboard/ts/components/AppDrawer.tsx
@@ -41,7 +41,6 @@ import HistoryIcon from "@mui/icons-material/History"
 import LanIcon from "@mui/icons-material/Lan"
 import { Switch } from "@mui/material"
 import { actionCreator } from "../action"
-import { URL_PREFIX } from "ts/types"
 
 const drawerWidth = 240
 
diff --git a/optuna_dashboard/ts/components/Artifact/ArtifactCardMedia.tsx b/optuna_dashboard/ts/components/Artifact/ArtifactCardMedia.tsx
index 69586a4a..8ffc70ba 100644
--- a/optuna_dashboard/ts/components/Artifact/ArtifactCardMedia.tsx
+++ b/optuna_dashboard/ts/components/Artifact/ArtifactCardMedia.tsx
@@ -6,7 +6,7 @@ import {
 import { WaveSurferArtifactViewer } from "./WaveSurferArtifactViewer"
 import InsertDriveFileIcon from "@mui/icons-material/InsertDriveFile"
 import { CardMedia, Box } from "@mui/material"
-import { Artifact } from "ts/types"
+import { Artifact } from "ts/types/optuna"
 
 export const ArtifactCardMedia: FC<{
   artifact: Artifact
diff --git a/optuna_dashboard/ts/components/Artifact/DeleteArtifactDialog.tsx b/optuna_dashboard/ts/components/Artifact/DeleteArtifactDialog.tsx
index 26056ad9..50e23df8 100644
--- a/optuna_dashboard/ts/components/Artifact/DeleteArtifactDialog.tsx
+++ b/optuna_dashboard/ts/components/Artifact/DeleteArtifactDialog.tsx
@@ -8,7 +8,7 @@ import {
   DialogActions,
 } from "@mui/material"
 import { actionCreator } from "../../action"
-import { Artifact } from "ts/types"
+import { Artifact } from "ts/types/optuna"
 
 export const useDeleteTrialArtifactDialog = (): [
   (studyId: number, trialId: number, artifact: Artifact) => void,
diff --git a/optuna_dashboard/ts/components/Artifact/StudyArtifactCards.tsx b/optuna_dashboard/ts/components/Artifact/StudyArtifactCards.tsx
index d4e3599a..361a8153 100644
--- a/optuna_dashboard/ts/components/Artifact/StudyArtifactCards.tsx
+++ b/optuna_dashboard/ts/components/Artifact/StudyArtifactCards.tsx
@@ -27,7 +27,7 @@ import {
   isThreejsArtifact,
 } from "./ThreejsArtifactViewer"
 import { ArtifactCardMedia } from "./ArtifactCardMedia"
-import { StudyDetail } from "ts/types"
+import { StudyDetail } from "ts/types/optuna"
 
 export const StudyArtifactCards: FC<{ study: StudyDetail }> = ({ study }) => {
   const theme = useTheme()
diff --git a/optuna_dashboard/ts/components/Artifact/ThreejsArtifactViewer.tsx b/optuna_dashboard/ts/components/Artifact/ThreejsArtifactViewer.tsx
index 141ea49e..954bca0a 100644
--- a/optuna_dashboard/ts/components/Artifact/ThreejsArtifactViewer.tsx
+++ b/optuna_dashboard/ts/components/Artifact/ThreejsArtifactViewer.tsx
@@ -9,7 +9,7 @@ import { PerspectiveCamera } from "three"
 import { Modal, Box, useTheme } from "@mui/material"
 import ClearIcon from "@mui/icons-material/Clear"
 import IconButton from "@mui/material/IconButton"
-import { Artifact } from "ts/types"
+import { Artifact } from "ts/types/optuna"
 
 export const isThreejsArtifact = (artifact: Artifact): boolean => {
   return (
diff --git a/optuna_dashboard/ts/components/Artifact/TrialArtifactCards.tsx b/optuna_dashboard/ts/components/Artifact/TrialArtifactCards.tsx
index e8f3bc8b..8f1cc971 100644
--- a/optuna_dashboard/ts/components/Artifact/TrialArtifactCards.tsx
+++ b/optuna_dashboard/ts/components/Artifact/TrialArtifactCards.tsx
@@ -27,7 +27,7 @@ import {
   isThreejsArtifact,
 } from "./ThreejsArtifactViewer"
 import { ArtifactCardMedia } from "./ArtifactCardMedia"
-import { Trial } from "ts/types"
+import { Trial } from "ts/types/optuna"
 
 export const TrialArtifactCards: FC<{ trial: Trial }> = ({ trial }) => {
   const theme = useTheme()
diff --git a/optuna_dashboard/ts/components/BestTrialsCard.tsx b/optuna_dashboard/ts/components/BestTrialsCard.tsx
index 255ba207..df92b444 100644
--- a/optuna_dashboard/ts/components/BestTrialsCard.tsx
+++ b/optuna_dashboard/ts/components/BestTrialsCard.tsx
@@ -14,7 +14,7 @@ import {
 } from "@mui/material"
 import { Link } from "react-router-dom"
 import LinkIcon from "@mui/icons-material/Link"
-import { StudyDetail, Trial, URL_PREFIX } from "ts/types"
+import { StudyDetail, Trial } from "ts/types/optuna"
 
 const useBestTrials = (studyDetail: StudyDetail | null): Trial[] => {
   return useMemo(() => studyDetail?.best_trials || [], [studyDetail])
diff --git a/optuna_dashboard/ts/components/CompareStudies.tsx b/optuna_dashboard/ts/components/CompareStudies.tsx
index 7dd26ffb..d6244a1e 100644
--- a/optuna_dashboard/ts/components/CompareStudies.tsx
+++ b/optuna_dashboard/ts/components/CompareStudies.tsx
@@ -32,7 +32,7 @@ import { GraphEdf } from "./GraphEdf"
 import { GraphHistory } from "./GraphHistory"
 import { useNavigate } from "react-router-dom"
 import { useQuery } from "../urlQuery"
-import { StudyDetails, StudySummary, URL_PREFIX } from "ts/types"
+import { StudyDetails, StudySummary } from "ts/types/optuna"
 
 const useQueriedStudies = (
   studies: StudySummary[],
diff --git a/optuna_dashboard/ts/components/CreateStudyDialog.tsx b/optuna_dashboard/ts/components/CreateStudyDialog.tsx
index dce10b05..ed4926ff 100644
--- a/optuna_dashboard/ts/components/CreateStudyDialog.tsx
+++ b/optuna_dashboard/ts/components/CreateStudyDialog.tsx
@@ -19,7 +19,7 @@ import { studySummariesState } from "../state"
 import RemoveIcon from "@mui/icons-material/Remove"
 import AddIcon from "@mui/icons-material/Add"
 import * as Optuna from "@optuna/types"
-import { StudySummary } from "ts/types"
+import { StudySummary } from "ts/types/optuna"
 
 export const useCreateStudyDialog = (): [() => void, () => ReactNode] => {
   const theme = useTheme()
diff --git a/optuna_dashboard/ts/components/GraphContour.tsx b/optuna_dashboard/ts/components/GraphContour.tsx
index e866cf1f..3d2d1a4c 100644
--- a/optuna_dashboard/ts/components/GraphContour.tsx
+++ b/optuna_dashboard/ts/components/GraphContour.tsx
@@ -20,7 +20,7 @@ import { getAxisInfo } from "../graphUtil"
 import { PlotType } from "../apiClient"
 import { useBackendRender } from "../state"
 import { usePlot } from "../hooks/usePlot"
-import { SearchSpaceItem, StudyDetail, Trial } from "ts/types"
+import { SearchSpaceItem, StudyDetail, Trial } from "ts/types/optuna"
 
 const plotDomId = "graph-contour"
 const CONTOUR_DISABLED_THRESHOLD = 100
diff --git a/optuna_dashboard/ts/components/GraphEdf.tsx b/optuna_dashboard/ts/components/GraphEdf.tsx
index 55258b7b..86be7802 100644
--- a/optuna_dashboard/ts/components/GraphEdf.tsx
+++ b/optuna_dashboard/ts/components/GraphEdf.tsx
@@ -4,7 +4,7 @@ import { Typography, useTheme, Box } from "@mui/material"
 import { Target, useFilteredTrialsFromStudies } from "../trialFilter"
 import { getCompareStudiesPlotAPI, CompareStudiesPlotType } from "../apiClient"
 import { usePlotlyColorTheme, useBackendRender } from "../state"
-import { StudyDetail, Trial } from "ts/types"
+import { StudyDetail, Trial } from "ts/types/optuna"
 
 const getPlotDomId = (objectiveId: number) => `graph-edf-${objectiveId}`
 
diff --git a/optuna_dashboard/ts/components/GraphHistory.tsx b/optuna_dashboard/ts/components/GraphHistory.tsx
index c06ea58e..784acc9b 100644
--- a/optuna_dashboard/ts/components/GraphHistory.tsx
+++ b/optuna_dashboard/ts/components/GraphHistory.tsx
@@ -23,7 +23,7 @@ import {
 import { usePlotlyColorTheme } from "../state"
 import { useNavigate } from "react-router-dom"
 import * as Optuna from "@optuna/types"
-import { StudyDetail, Trial, URL_PREFIX } from "ts/types"
+import { StudyDetail, Trial } from "ts/types/optuna"
 
 const plotDomId = "graph-history"
 
diff --git a/optuna_dashboard/ts/components/GraphHyperparameterImportances.tsx b/optuna_dashboard/ts/components/GraphHyperparameterImportances.tsx
index 2828ce44..4e20008a 100644
--- a/optuna_dashboard/ts/components/GraphHyperparameterImportances.tsx
+++ b/optuna_dashboard/ts/components/GraphHyperparameterImportances.tsx
@@ -10,7 +10,7 @@ import {
 } from "../state"
 import { PlotType } from "../apiClient"
 import { usePlot } from "../hooks/usePlot"
-import { ParamImportance, StudyDetail } from "ts/types"
+import { ParamImportance, StudyDetail } from "ts/types/optuna"
 
 const plotDomId = "graph-hyperparameter-importances"
 
diff --git a/optuna_dashboard/ts/components/GraphIntermediateValues.tsx b/optuna_dashboard/ts/components/GraphIntermediateValues.tsx
index 65085a97..db223946 100644
--- a/optuna_dashboard/ts/components/GraphIntermediateValues.tsx
+++ b/optuna_dashboard/ts/components/GraphIntermediateValues.tsx
@@ -2,7 +2,7 @@ import * as plotly from "plotly.js-dist-min"
 import React, { FC, useEffect } from "react"
 import { Box, Typography, useTheme, CardContent, Card } from "@mui/material"
 import { usePlotlyColorTheme } from "../state"
-import { Trial } from "ts/types"
+import { Trial } from "ts/types/optuna"
 
 const plotDomId = "graph-intermediate-values"
 
diff --git a/optuna_dashboard/ts/components/GraphParallelCoordinate.tsx b/optuna_dashboard/ts/components/GraphParallelCoordinate.tsx
index d26f10c7..cbbf1e2b 100644
--- a/optuna_dashboard/ts/components/GraphParallelCoordinate.tsx
+++ b/optuna_dashboard/ts/components/GraphParallelCoordinate.tsx
@@ -20,7 +20,7 @@ import { useMergedUnionSearchSpace } from "../searchSpace"
 import { PlotType } from "../apiClient"
 import { useBackendRender } from "../state"
 import { usePlot } from "../hooks/usePlot"
-import { SearchSpaceItem, StudyDetail, Trial } from "ts/types"
+import { SearchSpaceItem, StudyDetail, Trial } from "ts/types/optuna"
 
 const plotDomId = "graph-parallel-coordinate"
 
diff --git a/optuna_dashboard/ts/components/GraphParetoFront.tsx b/optuna_dashboard/ts/components/GraphParetoFront.tsx
index cac556b4..8e47844e 100644
--- a/optuna_dashboard/ts/components/GraphParetoFront.tsx
+++ b/optuna_dashboard/ts/components/GraphParetoFront.tsx
@@ -18,7 +18,7 @@ import { PlotType } from "../apiClient"
 import { useBackendRender } from "../state"
 import { usePlot } from "../hooks/usePlot"
 import * as Optuna from "@optuna/types"
-import { StudyDetail, Trial, URL_PREFIX } from "ts/types"
+import { StudyDetail, Trial } from "ts/types/optuna"
 
 const plotDomId = "graph-pareto-front"
 
diff --git a/optuna_dashboard/ts/components/GraphRank.tsx b/optuna_dashboard/ts/components/GraphRank.tsx
index 80125b25..fea3f4cd 100644
--- a/optuna_dashboard/ts/components/GraphRank.tsx
+++ b/optuna_dashboard/ts/components/GraphRank.tsx
@@ -16,7 +16,7 @@ import { useMergedUnionSearchSpace } from "../searchSpace"
 import { PlotType } from "../apiClient"
 import { usePlotlyColorTheme, useBackendRender } from "../state"
 import { usePlot } from "../hooks/usePlot"
-import { SearchSpaceItem, StudyDetail, Trial } from "ts/types"
+import { SearchSpaceItem, StudyDetail, Trial } from "ts/types/optuna"
 
 const plotDomId = "graph-rank"
 
diff --git a/optuna_dashboard/ts/components/GraphSlice.tsx b/optuna_dashboard/ts/components/GraphSlice.tsx
index 4e897b46..917d9254 100644
--- a/optuna_dashboard/ts/components/GraphSlice.tsx
+++ b/optuna_dashboard/ts/components/GraphSlice.tsx
@@ -22,7 +22,7 @@ import { useMergedUnionSearchSpace } from "../searchSpace"
 import { PlotType } from "../apiClient"
 import { usePlotlyColorTheme, useBackendRender } from "../state"
 import { usePlot } from "../hooks/usePlot"
-import { SearchSpaceItem, StudyDetail, Trial } from "ts/types"
+import { SearchSpaceItem, StudyDetail, Trial } from "ts/types/optuna"
 
 const plotDomId = "graph-slice"
 
diff --git a/optuna_dashboard/ts/components/GraphTimeline.tsx b/optuna_dashboard/ts/components/GraphTimeline.tsx
index bf71ba93..d0b54389 100644
--- a/optuna_dashboard/ts/components/GraphTimeline.tsx
+++ b/optuna_dashboard/ts/components/GraphTimeline.tsx
@@ -7,7 +7,7 @@ import { PlotType } from "../apiClient"
 import { useBackendRender } from "../state"
 import { usePlot } from "../hooks/usePlot"
 import * as Optuna from "@optuna/types"
-import { StudyDetail, Trial } from "ts/types"
+import { StudyDetail, Trial } from "ts/types/optuna"
 
 const plotDomId = "graph-timeline"
 const maxBars = 100
diff --git a/optuna_dashboard/ts/components/Note.tsx b/optuna_dashboard/ts/components/Note.tsx
index 7bcb34be..f54a3963 100644
--- a/optuna_dashboard/ts/components/Note.tsx
+++ b/optuna_dashboard/ts/components/Note.tsx
@@ -53,7 +53,7 @@ import { darcula } from "react-syntax-highlighter/dist/esm/styles/prism"
 import { actionCreator } from "../action"
 import { useRecoilValue } from "recoil"
 import { artifactIsAvailable, isFileUploading, useArtifacts } from "../state"
-import { Note } from "ts/types"
+import { Note } from "ts/types/optuna"
 
 const placeholder = `## What is this feature for?
 
diff --git a/optuna_dashboard/ts/components/Preferential/PreferentialGraph.tsx b/optuna_dashboard/ts/components/Preferential/PreferentialGraph.tsx
index 98514ba2..4e135d91 100644
--- a/optuna_dashboard/ts/components/Preferential/PreferentialGraph.tsx
+++ b/optuna_dashboard/ts/components/Preferential/PreferentialGraph.tsx
@@ -26,7 +26,7 @@ import { ElkNode } from "elkjs/lib/elk-api.js"
 import { useStudyDetailValue } from "../../state"
 import { getArtifactUrlPath } from "./PreferentialTrials"
 import { PreferentialOutputComponent } from "./PreferentialOutputComponent"
-import { StudyDetail, Trial } from "ts/types"
+import { StudyDetail, Trial } from "ts/types/optuna"
 
 const elk = new ELK()
 const nodeWidth = 400
diff --git a/optuna_dashboard/ts/components/Preferential/PreferentialHistory.tsx b/optuna_dashboard/ts/components/Preferential/PreferentialHistory.tsx
index a603ffdd..9f5c090b 100644
--- a/optuna_dashboard/ts/components/Preferential/PreferentialHistory.tsx
+++ b/optuna_dashboard/ts/components/Preferential/PreferentialHistory.tsx
@@ -21,7 +21,7 @@ import { formatDate } from "../../dateUtil"
 import { actionCreator } from "../../action"
 import { useStudyDetailValue } from "../../state"
 import { PreferentialOutputComponent } from "./PreferentialOutputComponent"
-import { PreferenceHistory, StudyDetail, Trial } from "ts/types"
+import { PreferenceHistory, StudyDetail, Trial } from "ts/types/optuna"
 
 type TrialType = "worst" | "none"
 
diff --git a/optuna_dashboard/ts/components/Preferential/PreferentialOutputComponent.tsx b/optuna_dashboard/ts/components/Preferential/PreferentialOutputComponent.tsx
index 3dc70c45..af45c6ec 100644
--- a/optuna_dashboard/ts/components/Preferential/PreferentialOutputComponent.tsx
+++ b/optuna_dashboard/ts/components/Preferential/PreferentialOutputComponent.tsx
@@ -1,7 +1,7 @@
 import React, { FC, useMemo } from "react"
 import { ArtifactCardMedia } from "../Artifact/ArtifactCardMedia"
 import { MarkdownRenderer } from "../Note"
-import { Artifact, FeedbackComponentType, Trial } from "ts/types"
+import { Artifact, FeedbackComponentType, Trial } from "ts/types/optuna"
 
 export const PreferentialOutputComponent: FC<{
   trial: Trial
diff --git a/optuna_dashboard/ts/components/Preferential/PreferentialTrials.tsx b/optuna_dashboard/ts/components/Preferential/PreferentialTrials.tsx
index b900202d..095e65ba 100644
--- a/optuna_dashboard/ts/components/Preferential/PreferentialTrials.tsx
+++ b/optuna_dashboard/ts/components/Preferential/PreferentialTrials.tsx
@@ -41,7 +41,7 @@ import {
   FeedbackComponentType,
   StudyDetail,
   Trial,
-} from "ts/types"
+} from "ts/types/optuna"
 
 const SettingsPage: FC<{
   studyDetail: StudyDetail
diff --git a/optuna_dashboard/ts/components/RenameStudyDialog.tsx b/optuna_dashboard/ts/components/RenameStudyDialog.tsx
index 05766f36..0765be3f 100644
--- a/optuna_dashboard/ts/components/RenameStudyDialog.tsx
+++ b/optuna_dashboard/ts/components/RenameStudyDialog.tsx
@@ -10,7 +10,7 @@ import {
 } from "@mui/material"
 import { actionCreator } from "../action"
 import { DebouncedInputTextField } from "./Debounce"
-import { StudySummary } from "ts/types"
+import { StudySummary } from "ts/types/optuna"
 
 export const useRenameStudyDialog = (
   studies: StudySummary[]
diff --git a/optuna_dashboard/ts/components/Settings.tsx b/optuna_dashboard/ts/components/Settings.tsx
index 036f8e32..feae3124 100644
--- a/optuna_dashboard/ts/components/Settings.tsx
+++ b/optuna_dashboard/ts/components/Settings.tsx
@@ -12,7 +12,7 @@ import {
 } from "@mui/material"
 import ClearIcon from "@mui/icons-material/Clear"
 import { usePlotBackendRendering, usePlotlyColorThemeState } from "../state"
-import { PlotlyColorThemeDark, PlotlyColorThemeLight } from "ts/types"
+import { PlotlyColorThemeDark, PlotlyColorThemeLight } from "ts/types/optuna"
 
 interface SettingsProps {
   handleClose: () => void
diff --git a/optuna_dashboard/ts/components/StudyDetail.tsx b/optuna_dashboard/ts/components/StudyDetail.tsx
index 9277b836..898856df 100644
--- a/optuna_dashboard/ts/components/StudyDetail.tsx
+++ b/optuna_dashboard/ts/components/StudyDetail.tsx
@@ -34,7 +34,6 @@ import { PreferentialTrials } from "./Preferential/PreferentialTrials"
 import { PreferentialHistory } from "./Preferential/PreferentialHistory"
 import { PreferentialAnalytics } from "./Preferential/PreferentialAnalytics"
 import { PreferentialGraph } from "./Preferential/PreferentialGraph"
-import { URL_PREFIX } from "ts/types"
 
 type ParamTypes = {
   studyId: string
diff --git a/optuna_dashboard/ts/components/StudyHistory.tsx b/optuna_dashboard/ts/components/StudyHistory.tsx
index 029c4d64..d112486a 100644
--- a/optuna_dashboard/ts/components/StudyHistory.tsx
+++ b/optuna_dashboard/ts/components/StudyHistory.tsx
@@ -27,7 +27,7 @@ import {
 import FormControlLabel from "@mui/material/FormControlLabel"
 import { artifactIsAvailable } from "../state"
 import * as Optuna from "@optuna/types"
-import { Trial } from "ts/types"
+import { Trial } from "ts/types/optuna"
 
 export const StudyHistory: FC<{ studyId: number }> = ({ studyId }) => {
   const theme = useTheme()
diff --git a/optuna_dashboard/ts/components/StudyList.tsx b/optuna_dashboard/ts/components/StudyList.tsx
index d4086888..b2dddd2b 100644
--- a/optuna_dashboard/ts/components/StudyList.tsx
+++ b/optuna_dashboard/ts/components/StudyList.tsx
@@ -39,7 +39,7 @@ import { useCreateStudyDialog } from "./CreateStudyDialog"
 import { useDeleteStudyDialog } from "./DeleteStudyDialog"
 import { useRenameStudyDialog } from "./RenameStudyDialog"
 import { useQuery } from "../urlQuery"
-import { StudySummary, URL_PREFIX } from "ts/types"
+import { StudySummary } from "ts/types/optuna"
 
 export const StudyList: FC<{
   toggleColorMode: () => void
diff --git a/optuna_dashboard/ts/components/TrialFormWidgets.tsx b/optuna_dashboard/ts/components/TrialFormWidgets.tsx
index ba0c3506..f870ccad 100644
--- a/optuna_dashboard/ts/components/TrialFormWidgets.tsx
+++ b/optuna_dashboard/ts/components/TrialFormWidgets.tsx
@@ -25,7 +25,7 @@ import {
   ObjectiveUserAttrRef,
   Trial,
   UserAttrFormWidget,
-} from "ts/types"
+} from "ts/types/optuna"
 
 type WidgetState = {
   isValid: boolean
diff --git a/optuna_dashboard/ts/components/TrialList.tsx b/optuna_dashboard/ts/components/TrialList.tsx
index 3398c62f..c6ea1028 100644
--- a/optuna_dashboard/ts/components/TrialList.tsx
+++ b/optuna_dashboard/ts/components/TrialList.tsx
@@ -31,7 +31,7 @@ import { TrialFormWidgets } from "./TrialFormWidgets"
 import { TrialArtifactCards } from "./Artifact/TrialArtifactCards"
 import { useQuery } from "../urlQuery"
 import { useVirtualizer } from "@tanstack/react-virtual"
-import { FormWidgets, StudyDetail, Trial, URL_PREFIX } from "ts/types"
+import { FormWidgets, StudyDetail, Trial } from "ts/types/optuna"
 
 const states: Optuna.TrialState[] = [
   "Complete",
diff --git a/optuna_dashboard/ts/components/TrialTable.tsx b/optuna_dashboard/ts/components/TrialTable.tsx
index 59dc2816..58dd7e0c 100644
--- a/optuna_dashboard/ts/components/TrialTable.tsx
+++ b/optuna_dashboard/ts/components/TrialTable.tsx
@@ -5,7 +5,7 @@ import DownloadIcon from "@mui/icons-material/Download"
 
 import { DataGridColumn, DataGrid } from "./DataGrid"
 import { Link } from "react-router-dom"
-import { StudyDetail, Trial, URL_PREFIX } from "ts/types"
+import { StudyDetail, Trial } from "ts/types/optuna"
 
 export const TrialTable: FC<{
   studyDetail: StudyDetail | null
diff --git a/optuna_dashboard/ts/components/UserDefinedPlot.tsx b/optuna_dashboard/ts/components/UserDefinedPlot.tsx
index e35f12ef..615b3e19 100644
--- a/optuna_dashboard/ts/components/UserDefinedPlot.tsx
+++ b/optuna_dashboard/ts/components/UserDefinedPlot.tsx
@@ -1,7 +1,7 @@
 import * as plotly from "plotly.js-dist-min"
 import React, { FC, useEffect } from "react"
 import { Box } from "@mui/material"
-import { PlotlyGraphObject } from "ts/types"
+import { PlotlyGraphObject } from "ts/types/optuna"
 
 export const UserDefinedPlot: FC<{
   graphObject: PlotlyGraphObject
diff --git a/optuna_dashboard/ts/dominatedTrials.ts b/optuna_dashboard/ts/dominatedTrials.ts
index 8c9f9374..e33b70b9 100644
--- a/optuna_dashboard/ts/dominatedTrials.ts
+++ b/optuna_dashboard/ts/dominatedTrials.ts
@@ -1,5 +1,5 @@
 import * as Optuna from "@optuna/types"
-import { Trial } from "./types"
+import { Trial } from "./types/optuna"
 
 const filterFunc = (
   trial: Trial,
diff --git a/optuna_dashboard/ts/graphUtil.ts b/optuna_dashboard/ts/graphUtil.ts
index 3db1e7f3..ecf6240a 100644
--- a/optuna_dashboard/ts/graphUtil.ts
+++ b/optuna_dashboard/ts/graphUtil.ts
@@ -1,4 +1,4 @@
-import { SearchSpaceItem, Trial } from "./types"
+import { SearchSpaceItem, Trial } from "./types/optuna"
 import * as Optuna from "@optuna/types"
 
 const PADDING_RATIO = 0.05
diff --git a/optuna_dashboard/ts/hooks/useParamImportance.ts b/optuna_dashboard/ts/hooks/useParamImportance.ts
index c96129da..36cb9f86 100644
--- a/optuna_dashboard/ts/hooks/useParamImportance.ts
+++ b/optuna_dashboard/ts/hooks/useParamImportance.ts
@@ -3,7 +3,7 @@ import { useSnackbar } from "notistack"
 import { getParamImportances } from "../apiClient"
 import { useQuery } from "@tanstack/react-query"
 import { AxiosError } from "axios"
-import { ParamImportance } from "ts/types"
+import { ParamImportance } from "ts/types/optuna"
 
 export const useParamImportance = ({
   numCompletedTrials,
diff --git a/optuna_dashboard/ts/searchSpace.ts b/optuna_dashboard/ts/searchSpace.ts
index 6363844a..abff8822 100644
--- a/optuna_dashboard/ts/searchSpace.ts
+++ b/optuna_dashboard/ts/searchSpace.ts
@@ -1,5 +1,5 @@
 import { useMemo } from "react"
-import { SearchSpaceItem } from "./types"
+import { SearchSpaceItem } from "./types/optuna"
 import * as Optuna from "@optuna/types"
 
 export const mergeUnionSearchSpace = (
diff --git a/optuna_dashboard/ts/state.ts b/optuna_dashboard/ts/state.ts
index a991c3a3..84a1d74a 100644
--- a/optuna_dashboard/ts/state.ts
+++ b/optuna_dashboard/ts/state.ts
@@ -11,7 +11,7 @@ import {
   StudyDetail,
   StudyDetails,
   StudySummary,
-} from "./types"
+} from "./types/optuna"
 
 export const studySummariesState = atom<StudySummary[]>({
   key: "studySummaries",
diff --git a/optuna_dashboard/ts/trialFilter.ts b/optuna_dashboard/ts/trialFilter.ts
index 2dabab04..111367b0 100644
--- a/optuna_dashboard/ts/trialFilter.ts
+++ b/optuna_dashboard/ts/trialFilter.ts
@@ -1,6 +1,6 @@
 import { useMemo, useState } from "react"
 import * as Optuna from "@optuna/types"
-import { SearchSpaceItem, StudyDetail, Trial } from "./types"
+import { SearchSpaceItem, StudyDetail, Trial } from "./types/optuna"
 
 type TargetKind = "objective" | "user_attr" | "params"
 
diff --git a/optuna_dashboard/ts/types/index.d.ts b/optuna_dashboard/ts/types/index.d.ts
index c28142ae..9175a554 100644
--- a/optuna_dashboard/ts/types/index.d.ts
+++ b/optuna_dashboard/ts/types/index.d.ts
@@ -6,196 +6,3 @@ declare module "*.svg"
 declare const APP_BAR_TITLE: string
 declare const API_ENDPOINT: string
 declare const URL_PREFIX: string
-
-import * as Optuna from "@optuna/types"
-
-type PreferenceFeedbackMode = "ChooseWorst"
-
-type GraphVisibility = {
-  history: boolean
-  paretoFront: boolean
-  parallelCoordinate: boolean
-  intermediateValues: boolean
-  edf: boolean
-  contour: boolean
-  importances: boolean
-  slice: boolean
-}
-
-type TrialParam = {
-  name: string
-  param_internal_value: number
-  param_external_value: string
-  param_external_type: string
-  distribution: Optuna.Distribution
-}
-
-type ParamImportance = {
-  name: string
-  importance: number
-  distribution: Optuna.Distribution
-}
-
-type SearchSpaceItem = {
-  name: string
-  distribution: Optuna.Distribution
-}
-
-type Note = {
-  version: number
-  body: string
-}
-
-type Artifact = {
-  artifact_id: string
-  filename: string
-  mimetype: string
-  encoding: string
-}
-
-type Trial = {
-  trial_id: number
-  study_id: number
-  number: number
-  state: Optuna.TrialState
-  values?: number[]
-  intermediate_values: Optuna.TrialIntermediateValue[]
-  datetime_start?: Date
-  datetime_complete?: Date
-  params: TrialParam[]
-  fixed_params: {
-    name: string
-    param_external_value: string
-  }[]
-  user_attrs: Optuna.Attribute[]
-  constraints: number[]
-  note: Note
-  artifacts: Artifact[]
-}
-
-type StudySummary = {
-  study_id: number
-  study_name: string
-  directions: Optuna.StudyDirection[]
-  user_attrs: Optuna.Attribute[]
-  is_preferential: boolean
-  datetime_start?: Date
-}
-
-type ObjectiveChoiceWidget = {
-  type: "choice"
-  description: string
-  user_attr_key?: string
-  choices: string[]
-  values: number[]
-}
-
-type ObjectiveSliderWidget = {
-  type: "slider"
-  description: string
-  user_attr_key?: string
-  min: number
-  max: number
-  step: number | null
-  labels:
-    | {
-        value: number
-        label: string
-      }[]
-    | null
-}
-
-type ObjectiveTextInputWidget = {
-  type: "text"
-  description: string
-  optional: boolean
-  user_attr_key?: string
-}
-
-type ObjectiveUserAttrRef = {
-  type: "user_attr"
-  key: string
-}
-
-type ObjectiveFormWidget =
-  | ObjectiveChoiceWidget
-  | ObjectiveSliderWidget
-  | ObjectiveTextInputWidget
-  | ObjectiveUserAttrRef
-
-type UserAttrFormWidget =
-  | ObjectiveChoiceWidget
-  | ObjectiveSliderWidget
-  | ObjectiveTextInputWidget
-
-type FormWidgets =
-  | {
-      output_type: "objective"
-      widgets: ObjectiveFormWidget[]
-    }
-  | {
-      output_type: "user_attr"
-      widgets: UserAttrFormWidget[]
-    }
-
-type PlotlyGraphObject = {
-  id: string
-  graph_object: string
-}
-
-type FeedbackComponentNote = {
-  output_type: "note"
-}
-
-type FeedbackComponentArtifact = {
-  output_type: "artifact"
-  artifact_key: string
-}
-
-type FeedbackComponentType = FeedbackComponentArtifact | FeedbackComponentNote
-
-type StudyDetail = {
-  id: number
-  name: string
-  directions: Optuna.StudyDirection[]
-  user_attrs: Optuna.Attribute[]
-  datetime_start: Date
-  best_trials: Trial[]
-  trials: Trial[]
-  intersection_search_space: SearchSpaceItem[]
-  union_search_space: SearchSpaceItem[]
-  union_user_attrs: Optuna.AttributeSpec[]
-  has_intermediate_values: boolean
-  note: Note
-  is_preferential: boolean
-  objective_names?: string[]
-  form_widgets?: FormWidgets
-  feedback_component_type: FeedbackComponentType
-  preferences?: [number, number][]
-  preference_history?: PreferenceHistory[]
-  plotly_graph_objects: PlotlyGraphObject[]
-  artifacts: Artifact[]
-  skipped_trial_numbers: number[]
-}
-
-type StudyDetails = {
-  [study_id: string]: StudyDetail
-}
-
-type PreferenceHistory = {
-  id: string
-  candidates: number[]
-  clicked: number
-  feedback_mode: PreferenceFeedbackMode
-  timestamp: Date
-  preferences: [number, number][]
-  is_removed: boolean
-}
-
-type PlotlyColorThemeDark = "default"
-type PlotlyColorThemeLight = "default" | "seaborn" | "presentation" | "ggplot2"
-
-type PlotlyColorTheme = {
-  dark: PlotlyColorThemeDark
-  light: PlotlyColorThemeLight
-}
diff --git a/optuna_dashboard/ts/types/optuna.ts b/optuna_dashboard/ts/types/optuna.ts
new file mode 100644
index 00000000..01844f72
--- /dev/null
+++ b/optuna_dashboard/ts/types/optuna.ts
@@ -0,0 +1,198 @@
+import * as Optuna from "@optuna/types"
+
+export type PreferenceFeedbackMode = "ChooseWorst"
+
+export type GraphVisibility = {
+  history: boolean
+  paretoFront: boolean
+  parallelCoordinate: boolean
+  intermediateValues: boolean
+  edf: boolean
+  contour: boolean
+  importances: boolean
+  slice: boolean
+}
+
+export type TrialParam = {
+  name: string
+  param_internal_value: number
+  param_external_value: string
+  param_external_type: string
+  distribution: Optuna.Distribution
+}
+
+export type ParamImportance = {
+  name: string
+  importance: number
+  distribution: Optuna.Distribution
+}
+
+export type SearchSpaceItem = {
+  name: string
+  distribution: Optuna.Distribution
+}
+
+export type Note = {
+  version: number
+  body: string
+}
+
+export type Artifact = {
+  artifact_id: string
+  filename: string
+  mimetype: string
+  encoding: string
+}
+
+export type Trial = {
+  trial_id: number
+  study_id: number
+  number: number
+  state: Optuna.TrialState
+  values?: number[]
+  intermediate_values: Optuna.TrialIntermediateValue[]
+  datetime_start?: Date
+  datetime_complete?: Date
+  params: TrialParam[]
+  fixed_params: {
+    name: string
+    param_external_value: string
+  }[]
+  user_attrs: Optuna.Attribute[]
+  constraints: number[]
+  note: Note
+  artifacts: Artifact[]
+}
+
+export type StudySummary = {
+  study_id: number
+  study_name: string
+  directions: Optuna.StudyDirection[]
+  user_attrs: Optuna.Attribute[]
+  is_preferential: boolean
+  datetime_start?: Date
+}
+
+export type ObjectiveChoiceWidget = {
+  type: "choice"
+  description: string
+  user_attr_key?: string
+  choices: string[]
+  values: number[]
+}
+
+export type ObjectiveSliderWidget = {
+  type: "slider"
+  description: string
+  user_attr_key?: string
+  min: number
+  max: number
+  step: number | null
+  labels:
+    | {
+        value: number
+        label: string
+      }[]
+    | null
+}
+
+export type ObjectiveTextInputWidget = {
+  type: "text"
+  description: string
+  optional: boolean
+  user_attr_key?: string
+}
+
+export type ObjectiveUserAttrRef = {
+  type: "user_attr"
+  key: string
+}
+
+export type ObjectiveFormWidget =
+  | ObjectiveChoiceWidget
+  | ObjectiveSliderWidget
+  | ObjectiveTextInputWidget
+  | ObjectiveUserAttrRef
+
+export type UserAttrFormWidget =
+  | ObjectiveChoiceWidget
+  | ObjectiveSliderWidget
+  | ObjectiveTextInputWidget
+
+export type FormWidgets =
+  | {
+      output_type: "objective"
+      widgets: ObjectiveFormWidget[]
+    }
+  | {
+      output_type: "user_attr"
+      widgets: UserAttrFormWidget[]
+    }
+
+export type PlotlyGraphObject = {
+  id: string
+  graph_object: string
+}
+
+export type FeedbackComponentNote = {
+  output_type: "note"
+}
+
+export type FeedbackComponentArtifact = {
+  output_type: "artifact"
+  artifact_key: string
+}
+
+export type FeedbackComponentType =
+  | FeedbackComponentArtifact
+  | FeedbackComponentNote
+
+export type StudyDetail = {
+  id: number
+  name: string
+  directions: Optuna.StudyDirection[]
+  user_attrs: Optuna.Attribute[]
+  datetime_start: Date
+  best_trials: Trial[]
+  trials: Trial[]
+  intersection_search_space: SearchSpaceItem[]
+  union_search_space: SearchSpaceItem[]
+  union_user_attrs: Optuna.AttributeSpec[]
+  has_intermediate_values: boolean
+  note: Note
+  is_preferential: boolean
+  objective_names?: string[]
+  form_widgets?: FormWidgets
+  feedback_component_type: FeedbackComponentType
+  preferences?: [number, number][]
+  preference_history?: PreferenceHistory[]
+  plotly_graph_objects: PlotlyGraphObject[]
+  artifacts: Artifact[]
+  skipped_trial_numbers: number[]
+}
+
+export type StudyDetails = {
+  [study_id: string]: StudyDetail
+}
+
+export type PreferenceHistory = {
+  id: string
+  candidates: number[]
+  clicked: number
+  feedback_mode: PreferenceFeedbackMode
+  timestamp: Date
+  preferences: [number, number][]
+  is_removed: boolean
+}
+
+export type PlotlyColorThemeDark = "default"
+export type PlotlyColorThemeLight =
+  | "default"
+  | "seaborn"
+  | "presentation"
+  | "ggplot2"
+
+export type PlotlyColorTheme = {
+  dark: PlotlyColorThemeDark
+  light: PlotlyColorThemeLight
+}