diff --git a/docker/images/java/Dockerfile b/docker/images/java/Dockerfile
deleted file mode 100644
index 4da394f975f76f503ab0089197b954f894e3acfb..0000000000000000000000000000000000000000
--- a/docker/images/java/Dockerfile
+++ /dev/null
@@ -1 +0,0 @@
-FROM baekjoon/onlinejudge-java:1.8
\ No newline at end of file
diff --git a/package.json b/package.json
index 064cf1d3cc25657442002bf470a698069cdde7df..6ed4420b6b5118fe3ab34759756727a7d7e908d8 100644
--- a/package.json
+++ b/package.json
@@ -3,6 +3,7 @@
   "version": "2.0.0",
   "description": "Algorithm Visualizer",
   "scripts": {
+    "postinstall": "docker pull baekjoon/onlinejudge-java:1.8",
     "dev": "NODE_ENV=development node bin/www",
     "start": "NODE_ENV=production node bin/www",
     "build": "npm run build:frontend && npm run build:backend",
diff --git a/src/backend/apis/index.js b/src/backend/apis/index.js
index cfee10c0f3a0cfb126eb2467e011990e5466f0c8..5aedb7235cab87e5f9c65b0c7237945aa23a3f28 100644
--- a/src/backend/apis/index.js
+++ b/src/backend/apis/index.js
@@ -1,14 +1,16 @@
 import Promise from 'bluebird';
 import axios from 'axios';
-import fs from 'fs-extra';
+import fs from 'fs';
 import { githubClientId, githubClientSecret } from '/environment';
 
-axios.interceptors.request.use(request => {
+const instance = axios.create();
+
+instance.interceptors.request.use(request => {
   request.params = { client_id: githubClientId, client_secret: githubClientSecret, ...request.params };
   return request;
 });
 
-axios.interceptors.response.use(response => {
+instance.interceptors.response.use(response => {
   return response.data;
 }, error => {
   return Promise.reject(error.response.data);
@@ -28,43 +30,43 @@ const request = (url, process) => {
 const GET = URL => {
   return request(URL, (mappedURL, args) => {
     const [params] = args;
-    return axios.get(mappedURL, { params });
+    return instance.get(mappedURL, { params });
   });
 };
 
 const DELETE = URL => {
   return request(URL, (mappedURL, args) => {
     const [params] = args;
-    return axios.delete(mappedURL, { params });
+    return instance.delete(mappedURL, { params });
   });
 };
 
 const POST = URL => {
   return request(URL, (mappedURL, args) => {
     const [body, params] = args;
-    return axios.post(mappedURL, body, { params });
+    return instance.post(mappedURL, body, { params });
   });
 };
 
 const PUT = URL => {
   return request(URL, (mappedURL, args) => {
     const [body, params] = args;
-    return axios.put(mappedURL, body, { params });
+    return instance.put(mappedURL, body, { params });
   });
 };
 
 const PATCH = URL => {
   return request(URL, (mappedURL, args) => {
     const [body, params] = args;
-    return axios.patch(mappedURL, body, { params });
+    return instance.patch(mappedURL, body, { params });
   });
 };
 
 const GitHubApi = {
   listCommits: GET('/repos/:owner/:repo/commits'),
-  getAccessToken: code => axios.post('https://github.com/login/oauth/access_token', { code }, { headers: { Accept: 'application/json' } }),
+  getAccessToken: code => instance.post('https://github.com/login/oauth/access_token', { code }, { headers: { Accept: 'application/json' } }),
   getLatestRelease: GET('/repos/:owner/:repo/releases/latest'),
-  download: (url, path) => axios({
+  download: (url, path) => instance({
     method: 'get',
     url,
     responseType: 'stream',
diff --git a/src/backend/common/error.js b/src/backend/common/error.js
index 1a0fccfc9d471a442fc001027d6f5775b6f92d8b..fefd65021558205daf18f1f2ab7b40d0432e8108 100644
--- a/src/backend/common/error.js
+++ b/src/backend/common/error.js
@@ -1,4 +1,7 @@
 class ApplicationError extends Error {
+  toJSON() {
+    return { message: this.message };
+  }
 }
 
 class NotFoundError extends ApplicationError {
@@ -10,9 +13,17 @@ class PermissionError extends ApplicationError {
 class AuthorizationError extends ApplicationError {
 }
 
+class CompileError extends ApplicationError {
+}
+
+class RuntimeError extends ApplicationError {
+}
+
 export {
   ApplicationError,
   NotFoundError,
   PermissionError,
   AuthorizationError,
+  CompileError,
+  RuntimeError,
 };
\ No newline at end of file
diff --git a/src/backend/controllers/categories.js b/src/backend/controllers/categories.js
index 7b1815845fad79d7578e5ef7959cf1479e19ce4c..3b7b1155484bac2e718179ae58867aa03d706388 100644
--- a/src/backend/controllers/categories.js
+++ b/src/backend/controllers/categories.js
@@ -1,5 +1,5 @@
 import express from 'express';
-import fs from 'fs-extra';
+import fs from 'fs';
 import path from 'path';
 import { NotFoundError } from '/common/error';
 import { exec } from 'child_process';
diff --git a/src/backend/controllers/compilers.js b/src/backend/controllers/compilers.js
deleted file mode 100644
index 3ae6df17d0afb881dcc8615fe1380c477933f6c4..0000000000000000000000000000000000000000
--- a/src/backend/controllers/compilers.js
+++ /dev/null
@@ -1,44 +0,0 @@
-import Promise from 'bluebird';
-import express from 'express';
-import fs from 'fs-extra';
-import uuid from 'uuid';
-import path from 'path';
-import { GitHubApi } from '/apis';
-
-const router = express.Router();
-
-const getLibPath = (...args) => path.resolve(__dirname, '..', 'public', 'libs', ...args);
-const createTempDir = () => {
-  const dirPath = path.resolve(__dirname, '..', 'public', 'codes', uuid.v4());
-  fs.mkdirSync(dirPath);
-  return dirPath;
-};
-
-const downloadLibs = () => {
-  GitHubApi.getLatestRelease('algorithm-visualizer', 'tracers').then(release => {
-    return Promise.each(release.assets, asset => GitHubApi.download(asset.browser_download_url, getLibPath(asset.name)));
-  });
-};
-downloadLibs(); // TODO: download again when webhooked
-
-const getJsWorker = (req, res, next) => {
-  res.sendFile(getLibPath('js.js'));
-};
-
-const compileJava = (req, res, next) => {
-  const dirPath = createTempDir();
-  fs.writeFileSync(dirPath, req.body);
-  /* TODO:
-  1. Write into a source file
-  2. Execute in Docker
-  3. Read the output file
-   */
-};
-
-router.route('/js')
-  .get(getJsWorker);
-
-router.route('/java')
-  .post(compileJava);
-
-export default router;
\ No newline at end of file
diff --git a/src/backend/controllers/index.js b/src/backend/controllers/index.js
index 9795620eca56a853ca0b1d04c9761742bf2f3f88..39cf1ef732e6a305b2b707314464a407f5a264b0 100644
--- a/src/backend/controllers/index.js
+++ b/src/backend/controllers/index.js
@@ -1,3 +1,3 @@
 export { default as auth } from './auth';
 export { default as categories } from './categories';
-export { default as compilers } from './compilers';
+export { default as tracers } from './tracers';
diff --git a/src/backend/controllers/tracers.js b/src/backend/controllers/tracers.js
new file mode 100644
index 0000000000000000000000000000000000000000..0aa448f13a76504a09970212b007ab08fcbab731
--- /dev/null
+++ b/src/backend/controllers/tracers.js
@@ -0,0 +1,56 @@
+import Promise from 'bluebird';
+import express from 'express';
+import fs from 'fs-extra';
+import uuid from 'uuid';
+import path from 'path';
+import child_process from 'child_process';
+import { GitHubApi } from '/apis';
+import { __PROD__ } from '/environment';
+import { CompileError, RuntimeError } from '/common/error';
+
+const router = express.Router();
+
+const getLibPath = (...args) => path.resolve(__dirname, '..', 'public', 'libs', ...args);
+
+const downloadLibs = () => {
+  GitHubApi.getLatestRelease('algorithm-visualizer', 'tracers').then(release => {
+    return Promise.each(release.assets, asset => GitHubApi.download(asset.browser_download_url, getLibPath(asset.name)));
+  });
+};
+if (__PROD__) downloadLibs(); // TODO: download again when webhooked
+
+const getJsWorker = (req, res, next) => {
+  res.sendFile(getLibPath('js.js'));
+};
+
+const execute = (imageId, srcPath, command, ErrorClass) => new Promise((resolve, reject) => {
+  const libPath = getLibPath();
+  const dockerCommand = `docker run --rm -w=/usr/judge -t -v=${libPath}:/usr/bin/tracers:ro -v=${srcPath}:/usr/judge:rw -e MAX_TRACES=1000000 -e MAX_TRACERS=100 ${imageId}`;
+  child_process.exec(`${dockerCommand} ${command}`, (error, stdout, stderr) => {
+    if (error) return reject(new ErrorClass(stdout));
+    resolve();
+  });
+});
+
+const trace = ({ imageId, compileCommand, runCommand }) => (req, res, next) => {
+  const { code } = req.body;
+  const srcPath = path.resolve(__dirname, '..', 'public', 'codes', uuid.v4());
+  fs.outputFile(path.resolve(srcPath, 'code.java'), code)
+    .then(() => execute(imageId, srcPath, compileCommand, CompileError))
+    .then(() => execute(imageId, srcPath, runCommand, RuntimeError))
+    .then(() => res.sendFile(path.resolve(srcPath, 'traces.json')))
+    .catch(next)
+    .finally(() => fs.remove(srcPath));
+};
+
+router.route('/js')
+  .get(getJsWorker);
+
+router.route('/java')
+  .post(trace({
+    imageId: 'baekjoon/onlinejudge-java:1.8',
+    compileCommand: 'javac -cp /usr/bin/tracers/java.jar code.java',
+    runCommand: 'java -cp /usr/bin/tracers/java.jar:. Main',
+  }));
+
+export default router;
\ No newline at end of file
diff --git a/src/frontend/apis/index.js b/src/frontend/apis/index.js
index a0427f7c7c1975c39602cdc38864ce3a7ad8add7..93a0e5d484b566fc9ff568c2ba5b751b2ac70a90 100644
--- a/src/frontend/apis/index.js
+++ b/src/frontend/apis/index.js
@@ -69,18 +69,19 @@ const GitHubApi = {
 };
 
 let jsWorker = null;
-const CompilerApi = {
-  js: code => new Promise((resolve, reject) => {
+const TracerApi = {
+  js: ({ code }) => new Promise((resolve, reject) => {
     if (jsWorker) jsWorker.terminate();
-    jsWorker = new Worker('/api/compilers/js');
+    jsWorker = new Worker('/api/tracers/js');
     jsWorker.onmessage = e => resolve(e.data);
     jsWorker.onerror = reject;
     jsWorker.postMessage(code);
   }),
+  java: POST('/tracers/java'),
 };
 
 export {
   CategoryApi,
   GitHubApi,
-  CompilerApi,
+  TracerApi,
 };
\ No newline at end of file
diff --git a/src/frontend/components/ToastContainer/stylesheet.scss b/src/frontend/components/ToastContainer/stylesheet.scss
index 0bcd13e3203e1d400beca4d9a4b5d9266e95459f..e790e9531f925ee3af514c3592771335ba2defe9 100644
--- a/src/frontend/components/ToastContainer/stylesheet.scss
+++ b/src/frontend/components/ToastContainer/stylesheet.scss
@@ -13,6 +13,7 @@
   padding: 16px;
   margin: 8px;
   font-size: $font-size-large;
+  white-space: pre-line;
 
   &.success {
     border-color: rgb(0, 150, 0);
diff --git a/src/frontend/core/tracerManager.jsx b/src/frontend/core/tracerManager.jsx
index b426d819a2d42bb3dddd1ec1a3c3460a4d1650de..d8223a231cc2a2424a6758c86efcdc75dff9dfb2 100644
--- a/src/frontend/core/tracerManager.jsx
+++ b/src/frontend/core/tracerManager.jsx
@@ -3,7 +3,7 @@ import Promise from 'bluebird';
 import { extension } from '/common/util';
 import { Array1DData, Array2DData, ChartData, Data, GraphData, LogData } from '/core/datas';
 import { Array1DRenderer, Array2DRenderer, ChartRenderer, GraphRenderer, LogRenderer, Renderer } from '/core/renderers';
-import { CompilerApi } from '/apis';
+import { TracerApi } from '/apis';
 
 class TracerManager {
   constructor() {
@@ -63,7 +63,7 @@ class TracerManager {
 
   setFile(file) {
     this.file = file;
-    this.runInitial();
+    if (extension(file.name) === 'js') this.runInitial();
   }
 
   reset(traces = []) {
@@ -155,8 +155,12 @@ class TracerManager {
   execute() {
     const { name, content } = this.file;
     const ext = extension(name);
-    if (ext in CompilerApi) {
-      return CompilerApi[ext](content).then(traces => this.reset(traces));
+    if (ext in TracerApi) {
+      return TracerApi[ext]({ code: content })
+        .then(traces => this.reset(traces))
+        .catch(e => {
+          throw e.err;
+        });
     } else {
       return Promise.reject(new Error('Language Not Supported'));
     }