diff --git a/packages/hydrojudge/src/check.ts b/packages/hydrojudge/src/check.ts
index 8ac5d357..531a4d8c 100644
--- a/packages/hydrojudge/src/check.ts
+++ b/packages/hydrojudge/src/check.ts
@@ -3,11 +3,24 @@ import { findFileSync } from '@hydrooj/utils/lib/utils';
 import checkers from './checkers';
 import compile from './compile';
 import { SystemError } from './error';
+import { Execute } from './interface';
+import { CopyInFile } from './sandbox/interface';
 import { parseFilename } from './utils';
 
 const testlibSrc = findFileSync('@hydrooj/hydrojudge/vendor/testlib/testlib.h');
 
-export async function check(config): Promise<[number, number, string]> {
+interface CheckConfig {
+    checker_type: string;
+    stdin: string,
+    stdout: string,
+    user_stdout: string,
+    user_stderr: string,
+    score: number,
+    copyIn?: Record<string, CopyInFile>,
+    detail: boolean,
+}
+
+export async function check(config: CheckConfig): Promise<[number, number, string]> {
     if (!checkers[config.checker_type]) throw new SystemError('Unknown checker type {0}', [config.checker_type]);
     const {
         code, status, score, message,
@@ -24,7 +37,7 @@ export async function check(config): Promise<[number, number, string]> {
     return [status, score, message];
 }
 
-export async function compileChecker(getLang: Function, checkerType: string, checker: string, copyIn: any) {
+export async function compileChecker(getLang: Function, checkerType: string, checker: string, copyIn: any): Promise<Execute> {
     if (!checkers[checkerType]) throw new SystemError('Unknown checker type {0}.', [checkerType]);
     if (checkerType === 'testlib') copyIn['testlib.h'] = { src: testlibSrc };
     const file = await fs.readFile(checker);
diff --git a/packages/hydrojudge/src/checkers.ts b/packages/hydrojudge/src/checkers.ts
index 9477db01..add33411 100644
--- a/packages/hydrojudge/src/checkers.ts
+++ b/packages/hydrojudge/src/checkers.ts
@@ -2,8 +2,19 @@
 import { STATUS } from '@hydrooj/utils/lib/status';
 import { SystemError } from './error';
 import { run } from './sandbox';
+import { CopyInFile } from './sandbox/interface';
 import { parse } from './testlib';
 
+interface CheckConfig {
+    input: string,
+    output: string,
+    user_stdout: string,
+    user_stderr: string,
+    score: number,
+    copyIn: Record<string, CopyInFile>,
+    detail: boolean,
+}
+
 interface CheckResult {
     status: number,
     score: number,
@@ -11,7 +22,7 @@ interface CheckResult {
     code?: number,
 }
 
-type Checker = (config: any) => Promise<CheckResult>;
+type Checker = (config: CheckConfig) => Promise<CheckResult>;
 
 const checkers: Record<string, Checker> = {
     async default(config) {
@@ -22,7 +33,7 @@ const checkers: Record<string, Checker> = {
                 ...config.copyIn,
             },
         });
-        let status;
+        let status: number;
         let message: any = '';
         if (stdout) {
             status = STATUS.STATUS_WRONG_ANSWER;
diff --git a/packages/hydrojudge/src/daemon.ts b/packages/hydrojudge/src/daemon.ts
index 97ffdf4e..858f12fe 100644
--- a/packages/hydrojudge/src/daemon.ts
+++ b/packages/hydrojudge/src/daemon.ts
@@ -23,19 +23,19 @@ import { Queue, sleep } from './utils';
 declare global {
     namespace NodeJS {
         interface Global {
-            onDestory: Function[]
+            onDestroy: Function[]
             hosts: any
         }
     }
 }
-if (!global.onDestory) global.onDestory = [];
+if (!global.onDestroy) global.onDestroy = [];
 if (!global.hosts) global.hosts = [];
 let exit = false;
 
 const terminate = async () => {
     log.info('正在保存数据');
     try {
-        await Promise.all(global.onDestory.map((f) => f()));
+        await Promise.all(global.onDestroy.map((f: Function) => f()));
         process.exit(1);
     } catch (e) {
         if (exit) process.exit(1);
diff --git a/packages/hydrojudge/src/hosts/hydro.ts b/packages/hydrojudge/src/hosts/hydro.ts
index dc8f79e8..13784927 100644
--- a/packages/hydrojudge/src/hosts/hydro.ts
+++ b/packages/hydrojudge/src/hosts/hydro.ts
@@ -63,7 +63,7 @@ class JudgeTask {
         this.source = this.request.source;
         this.tmpdir = path.resolve(getConfig('tmp_dir'), this.host, this.rid);
         this.clean = [];
-        await Lock.aquire(`${this.host}/${this.source}/${this.rid}`);
+        await Lock.acquire(`${this.host}/${this.source}/${this.rid}`);
         fs.ensureDirSync(this.tmpdir);
         tmpfs.mount(this.tmpdir, getConfig('tmpfs_size'));
         log.info('Submission: %s/%s/%s', this.host, this.source, this.rid);
@@ -170,7 +170,7 @@ export default class Hydro {
     }
 
     async cacheOpen(source: string, files: any[], next?) {
-        await Lock.aquire(`${this.config.host}/${source}`);
+        await Lock.acquire(`${this.config.host}/${source}`);
         try {
             return this._cacheOpen(source, files, next);
         } finally {
@@ -245,7 +245,7 @@ export default class Hydro {
         this.ws = new WebSocket(`${this.config.server_url.replace(/^http/i, 'ws')}judge/conn/websocket?t=${res.data.entropy}`);
         this.ws.on('open', () => {
             this.ws.send(this.config.cookie);
-            global.onDestory.push(() => this.ws.close());
+            global.onDestroy.push(() => this.ws.close());
             const content = this.config.minPriority !== undefined
                 ? `{"key":"prio","prio":${this.config.minPriority}}`
                 : '{"key":"ping"}';
diff --git a/packages/hydrojudge/src/interface.ts b/packages/hydrojudge/src/interface.ts
index 00fa83ac..99c7fc4e 100644
--- a/packages/hydrojudge/src/interface.ts
+++ b/packages/hydrojudge/src/interface.ts
@@ -1,12 +1,8 @@
-export interface SFile {
-    src?: string,
-    content?: string,
-    fileId?: string,
-}
+import { CopyInFile } from './sandbox/interface';
 export interface Execute {
     execute: string,
     clean: Function,
-    copyIn: Record<string, SFile>,
+    copyIn: Record<string, CopyInFile>,
     time?: number,
 }
 export interface CompileErrorInfo {
diff --git a/packages/hydrojudge/src/judge/default.ts b/packages/hydrojudge/src/judge/default.ts
index a3f6b9cd..d3a863a0 100644
--- a/packages/hydrojudge/src/judge/default.ts
+++ b/packages/hydrojudge/src/judge/default.ts
@@ -9,6 +9,9 @@ import { CompileError, FormatError } from '../error';
 import { run } from '../sandbox';
 import signals from '../signals';
 import { parseFilename } from '../utils';
+import {
+    Case, Context, ContextSubTask, SubTask,
+} from './interface';
 
 const Score = {
     sum: (a: number, b: number) => (a + b),
@@ -16,8 +19,8 @@ const Score = {
     min: Math.min,
 };
 
-function judgeCase(c, sid: string) {
-    return async (ctx, ctxSubtask, runner?: Function) => {
+function judgeCase(c: Case, sid: string) {
+    return async (ctx: Context, ctxSubtask: ContextSubTask, runner?: Function) => {
         if (ctx.errored || (ctx.failed[sid] && ctxSubtask.subtask.type === 'min')
             || (ctxSubtask.subtask.type === 'max' && ctxSubtask.score === ctxSubtask.subtask.score)
             || ((ctxSubtask.subtask.if || []).filter((i: string) => ctx.failed[i]).length)
@@ -72,7 +75,6 @@ function judgeCase(c, sid: string) {
                     stdout: c.output,
                     user_stdout: stdout,
                     user_stderr: stderr,
-                    checker: ctx.config.checker,
                     checker_type: ctx.config.checker_type,
                     score: ctxSubtask.subtask.score,
                     detail: ctx.config.detail ?? true,
@@ -109,8 +111,8 @@ function judgeCase(c, sid: string) {
     };
 }
 
-function judgeSubtask(subtask, sid: string) {
-    return async (ctx) => {
+function judgeSubtask(subtask: SubTask, sid: string) {
+    return async (ctx: Context) => {
         subtask.type = subtask.type || 'min';
         const ctxSubtask = {
             subtask,
@@ -133,7 +135,7 @@ function judgeSubtask(subtask, sid: string) {
     };
 }
 
-export const judge = async (ctx) => {
+export const judge = async (ctx: Context) => {
     if (!ctx.config.subtasks.length) throw new FormatError('Problem data not found.');
     ctx.next({ status: STATUS.STATUS_COMPILING });
     if (ctx.config.template) {
diff --git a/packages/hydrojudge/src/judge/hack.ts b/packages/hydrojudge/src/judge/hack.ts
index cc39baac..1bd07402 100644
--- a/packages/hydrojudge/src/judge/hack.ts
+++ b/packages/hydrojudge/src/judge/hack.ts
@@ -8,8 +8,9 @@ import { CompileError } from '../error';
 import { run } from '../sandbox';
 import signals from '../signals';
 import { copyInDir, parseFilename } from '../utils';
+import { Context } from './interface';
 
-export const judge = async (ctx) => {
+export const judge = async (ctx: Context) => {
     if (ctx.config.template) {
         if (ctx.config.template[ctx.lang]) {
             const tpl = ctx.config.template[ctx.lang];
@@ -100,7 +101,6 @@ export const judge = async (ctx) => {
                 stdout,
                 user_stdout: stdout,
                 user_stderr: stderr,
-                checker: ctx.config.checker,
                 checker_type: ctx.config.checker_type,
                 score: 100,
                 detail: ctx.config.detail,
diff --git a/packages/hydrojudge/src/judge/index.ts b/packages/hydrojudge/src/judge/index.ts
index 76622f43..2d0af9ed 100644
--- a/packages/hydrojudge/src/judge/index.ts
+++ b/packages/hydrojudge/src/judge/index.ts
@@ -1,9 +1,10 @@
 import * as def from './default';
 import * as hack from './hack';
 import * as interactive from './interactive';
+import { Context } from './interface';
 import * as run from './run';
 import * as submit_answer from './submit_answer';
 
 export = {
     default: def, interactive, run, submit_answer, hack, objective: submit_answer,
-};
+} as Record<string, { judge(ctx: Context): Promise<void> }>;
diff --git a/packages/hydrojudge/src/judge/interactive.ts b/packages/hydrojudge/src/judge/interactive.ts
index 42d33547..f5e72c82 100644
--- a/packages/hydrojudge/src/judge/interactive.ts
+++ b/packages/hydrojudge/src/judge/interactive.ts
@@ -7,16 +7,19 @@ import { run } from '../sandbox';
 import signals from '../signals';
 import { parse } from '../testlib';
 import { findFileSync, parseFilename } from '../utils';
+import {
+    Case, Context, ContextSubTask, SubTask,
+} from './interface';
 
 const testlibSrc = findFileSync('@hydrooj/hydrojudge/vendor/testlib/testlib.h');
 const Score = {
-    sum: (a, b) => (a + b),
+    sum: (a: number, b: number) => (a + b),
     max: Math.max,
     min: Math.min,
 };
 
-function judgeCase(c) {
-    return async (ctx, ctxSubtask) => {
+function judgeCase(c: Case) {
+    return async (ctx: Context, ctxSubtask: ContextSubTask) => {
         ctx.executeInteractor.copyIn.in = c.input ? { src: c.input } : { content: '' };
         ctx.executeInteractor.copyIn.out = c.output ? { src: c.output } : { content: '' };
         const [{ code, time_usage_ms, memory_usage_kb }, resInteractor] = await run([
@@ -34,7 +37,7 @@ function judgeCase(c) {
             },
         ]);
         // TODO handle tout (maybe pass to checker?)
-        let status;
+        let status: number;
         let score = 0;
         let message: any = '';
         if (time_usage_ms > ctxSubtask.subtask.time * ctx.executeUser.time) {
@@ -70,8 +73,8 @@ function judgeCase(c) {
     };
 }
 
-function judgeSubtask(subtask) {
-    return async (ctx) => {
+function judgeSubtask(subtask: SubTask) {
+    return async (ctx: Context) => {
         subtask.type = subtask.type || 'min';
         const ctxSubtask = {
             subtask,
@@ -90,7 +93,7 @@ function judgeSubtask(subtask) {
     };
 }
 
-export const judge = async (ctx) => {
+export const judge = async (ctx: Context) => {
     ctx.next({ status: STATUS.STATUS_COMPILING });
     [ctx.executeUser, ctx.executeInteractor] = await Promise.all([
         (() => {
diff --git a/packages/hydrojudge/src/judge/interface.ts b/packages/hydrojudge/src/judge/interface.ts
new file mode 100644
index 00000000..e1f54ee9
--- /dev/null
+++ b/packages/hydrojudge/src/judge/interface.ts
@@ -0,0 +1,101 @@
+import PQueue from 'p-queue';
+import { LangConfig } from '@hydrooj/utils/lib/lang';
+import { Execute } from '../interface';
+
+export type Context = JudgeTaskInterface & RuntimeContext;
+
+export interface JudgeTaskInterface {
+    next(arg0: {
+        status?: number;
+        message?: string;
+        progress?: number;
+        case?: {
+            status: number;
+            score?: number;
+            time_ms: number;
+            memory_kb: number;
+            message: string;
+        };
+    }, arg1?: number): void;
+    end(arg0: {
+        status: number;
+        score: number;
+        time_ms: number;
+        memory_kb: number;
+    }): void;
+    getLang: (name: string) => LangConfig;
+
+    stat: Record<string, Date>;
+    lang: string;
+    code: string;
+    tmpdir: string;
+    input?: string;
+    clean: Function[];
+    config: Config;
+}
+
+export interface RuntimeContext {
+    total_score?: number;
+    total_status?: number;
+    total_time_usage_ms?: number;
+    total_memory_usage_kb?: number;
+
+    queue?: PQueue;
+    errored?: boolean;
+    rerun?: number;
+    failed?: Record<string, boolean>;
+
+    execute?: Execute;
+    checker?: Execute;
+    executeInteractor?: Execute;
+    executeUser?: Execute;
+}
+
+type ExtraFile = string[];
+
+export interface Config {
+    time: string;
+    memory: string;
+
+    subtasks?: SubTask[];
+    count?: number;
+    checker_type?: string;
+    detail?: boolean;
+    filename?: string;
+
+    judge_extra_files?: ExtraFile;
+    user_extra_files?: ExtraFile;
+    template?: Record<string, [string, string]>;
+
+    checker?: string;
+    validator?: string;
+    std?: string;
+    hack?: string;
+    interactor?: string;
+
+    outputs?: {
+        output: string,
+        score: number,
+    }[];
+}
+
+export interface SubTask {
+    time: number;
+    memory: number;
+    type: 'sum' | 'max' | 'min';
+    score: number;
+    cases: Record<string, Case>;
+    if: string[];
+}
+
+export interface ContextSubTask {
+    subtask: SubTask;
+    score: number;
+    status: number;
+}
+
+export interface Case {
+    id: number;
+    input: string;
+    output: string;
+}
diff --git a/packages/hydrojudge/src/judge/run.ts b/packages/hydrojudge/src/judge/run.ts
index fba3ca8b..f5bde47f 100644
--- a/packages/hydrojudge/src/judge/run.ts
+++ b/packages/hydrojudge/src/judge/run.ts
@@ -6,8 +6,9 @@ import { CompileError } from '../error';
 import { run } from '../sandbox';
 import signals from '../signals';
 import { compilerText, parseMemoryMB, parseTimeMS } from '../utils';
+import { Context } from './interface';
 
-export const judge = async (ctx) => {
+export const judge = async (ctx: Context) => {
     ctx.stat.judge = new Date();
     ctx.next({ status: STATUS.STATUS_COMPILING });
     try {
diff --git a/packages/hydrojudge/src/judge/submit_answer.ts b/packages/hydrojudge/src/judge/submit_answer.ts
index 7a724fbe..1e87800f 100644
--- a/packages/hydrojudge/src/judge/submit_answer.ts
+++ b/packages/hydrojudge/src/judge/submit_answer.ts
@@ -1,8 +1,9 @@
 import { STATUS } from '@hydrooj/utils/lib/status';
+import { Context } from './interface';
 
 export async function judge({
     next, end, config, code,
-}) {
+}: Context) {
     next({ status: STATUS.STATUS_JUDGING, progress: 0 });
     code = code.replace(/\r/g, '');
     const outputs = code.split('\n');
diff --git a/packages/hydrojudge/src/log.ts b/packages/hydrojudge/src/log.ts
index dbc9a0bf..193f384d 100644
--- a/packages/hydrojudge/src/log.ts
+++ b/packages/hydrojudge/src/log.ts
@@ -91,7 +91,7 @@ export class Logger {
     private createMethod(name: LogType, prefix: string, minLevel: number) {
         this[name] = (...args: [any, ...any[]]) => {
             if (this.level < minLevel) return;
-            this.stream.write(`${prefix + this.displayName + this.format(...args)}\n`);
+            this.stream.write(`${prefix} ${this.displayName} ${this.format(...args)}\n`);
         };
     }
 
diff --git a/packages/hydrojudge/src/sandbox.ts b/packages/hydrojudge/src/sandbox.ts
index 906cfdb6..f022904f 100644
--- a/packages/hydrojudge/src/sandbox.ts
+++ b/packages/hydrojudge/src/sandbox.ts
@@ -1,10 +1,14 @@
-import Axios from 'axios';
 import cac from 'cac';
 import fs from 'fs-extra';
+import { ParseEntry } from 'shell-quote';
 import { STATUS } from '@hydrooj/utils/lib/status';
 import { getConfig } from './config';
 import { FormatError, SystemError } from './error';
 import { Logger } from './log';
+import { SandboxClient } from './sandbox/client';
+import {
+    Cmd, CopyInFile, SandboxResult, SandboxStatus,
+} from './sandbox/interface';
 import { cmd, parseMemoryMB } from './utils';
 
 const argv = cac().parse();
@@ -12,16 +16,41 @@ const logger = new Logger('sandbox');
 let callId = 0;
 let supportOptional = false;
 
-const statusMap = {
-    'Time Limit Exceeded': STATUS.STATUS_TIME_LIMIT_EXCEEDED,
-    'Memory Limit Exceeded': STATUS.STATUS_MEMORY_LIMIT_EXCEEDED,
-    'Output Limit Exceeded': STATUS.STATUS_RUNTIME_ERROR,
-    Accepted: STATUS.STATUS_ACCEPTED,
-    'Nonzero Exit Status': STATUS.STATUS_RUNTIME_ERROR,
-    'Internal Error': STATUS.STATUS_SYSTEM_ERROR,
-    'File Error': STATUS.STATUS_SYSTEM_ERROR,
-    Signalled: STATUS.STATUS_RUNTIME_ERROR,
-};
+const statusMap: Map<SandboxStatus, number> = new Map([
+    [SandboxStatus.TimeLimitExceeded, STATUS.STATUS_TIME_LIMIT_EXCEEDED],
+    [SandboxStatus.MemoryLimitExceeded, STATUS.STATUS_MEMORY_LIMIT_EXCEEDED],
+    [SandboxStatus.OutputLimitExceeded, STATUS.STATUS_RUNTIME_ERROR],
+    [SandboxStatus.Accepted, STATUS.STATUS_ACCEPTED],
+    [SandboxStatus.NonzeroExitStatus, STATUS.STATUS_RUNTIME_ERROR],
+    [SandboxStatus.InternalError, STATUS.STATUS_SYSTEM_ERROR],
+    [SandboxStatus.FileError, STATUS.STATUS_SYSTEM_ERROR],
+    [SandboxStatus.Signalled, STATUS.STATUS_RUNTIME_ERROR],
+]);
+
+interface Parameter {
+    time?: number;
+    stdin?: string;
+    stdout?: string;
+    stderr?: string;
+    execute?: string;
+    memory?: number;
+    processLimit?: number;
+    copyIn?: Record<string, CopyInFile>;
+    copyOut?: string[];
+    copyOutCached?: string[];
+}
+
+function checkStringArray(args: ParseEntry[]): args is string[] {
+    return args.every((arg: ParseEntry) => typeof arg === 'string');
+}
+
+function parseArgs(execute: string): string[] {
+    const args = cmd(execute.replace(/\$\{dir\}/g, '/w'));
+    if (!checkStringArray(args)) {
+        throw new SystemError(`${execute} contains invalid operator`);
+    }
+    return args;
+}
 
 function proc({
     execute = '',
@@ -29,14 +58,14 @@ function proc({
     memory = parseMemoryMB(getConfig('memoryMax')),
     processLimit = getConfig('processLimit'),
     stdin = '', copyIn = {}, copyOut = [], copyOutCached = [],
-} = {}) {
+}: Parameter = {}): Cmd {
     if (!supportOptional) {
         copyOut = (copyOut as string[]).map((i) => (i.endsWith('?') ? i.substr(0, i.length - 1) : i));
     }
     const size = parseMemoryMB(getConfig('stdio_size'));
     const rate = getConfig('rate');
     return {
-        args: cmd(execute.replace(/\$\{dir\}/g, '/w')),
+        args: parseArgs(execute),
         env: getConfig('env').split('\n'),
         files: [
             stdin ? { src: stdin } : { content: '' },
@@ -44,7 +73,7 @@ function proc({
             { name: 'stderr', max: Math.floor(1024 * 1024 * size) },
         ],
         cpuLimit: Math.floor(time * 1000 * 1000 * rate),
-        realCpuLimit: Math.floor(time * 3000 * 1000 * rate),
+        clockLimit: Math.floor(time * 3000 * 1000 * rate),
         memoryLimit: Math.floor(memory * 1024 * 1024),
         strictMemoryLimit: getConfig('strict_memory'),
         // stackLimit: memory * 1024 * 1024,
@@ -55,11 +84,11 @@ function proc({
     };
 }
 
-async function adaptResult(result, params) {
+async function adaptResult(result: SandboxResult, params: Parameter) {
     const rate = getConfig('rate');
     // FIXME: Signalled?
     const ret: any = {
-        status: statusMap[result.status] || STATUS.STATUS_ACCEPTED,
+        status: statusMap.get(result.status) || STATUS.STATUS_ACCEPTED,
         time_usage_ms: result.time / 1000000 / rate,
         memory_usage_kb: result.memory / 1024,
         files: result.files,
@@ -78,8 +107,8 @@ async function adaptResult(result, params) {
     return ret;
 }
 
-export async function runMultiple(execute) {
-    let res;
+export async function runMultiple(execute: Parameter[]) {
+    let res: SandboxResult[];
     const size = parseMemoryMB(getConfig('stdio_size'));
     try {
         const body = {
@@ -107,35 +136,35 @@ export async function runMultiple(execute) {
         body.cmd[1].files[1] = null;
         const id = callId++;
         if (argv.options.showSandbox) logger.debug('%d %s', id, JSON.stringify(body));
-        res = await Axios.create({ baseURL: getConfig('sandbox_host') }).post('/run', body);
-        if (argv.options.showSandbox) logger.debug('%d %s', id, JSON.stringify(res.data));
+        res = await new SandboxClient(getConfig('sandbox_host')).run(body);
+        if (argv.options.showSandbox) logger.debug('%d %s', id, JSON.stringify(res));
     } catch (e) {
         if (e instanceof FormatError) throw e;
         throw new SystemError('Sandbox Error', [e]);
     }
-    return await Promise.all(res.data.map((i) => adaptResult(i, {})));
+    return await Promise.all(res.map((r) => adaptResult(r, {})));
 }
 
 export async function del(fileId: string) {
-    const res = await Axios.create({ baseURL: getConfig('sandbox_host') }).delete(`/file/${fileId}`);
-    return res.data;
+    await new SandboxClient(getConfig('sandbox_host')).deleteFile(fileId);
 }
 
-export async function run(execute, params?) {
-    let result;
+export async function run(execute: string | Parameter[], params?: Parameter) {
+    let result: SandboxResult;
     if (typeof execute === 'object') return await runMultiple(execute);
     try {
+        const client = new SandboxClient(getConfig('sandbox_host'));
         if (!supportOptional) {
-            const res = await Axios.create({ baseURL: getConfig('sandbox_host') }).get('/version');
-            supportOptional = res.data.copyOutOptional;
+            const res = await client.version();
+            supportOptional = res.copyOutOptional;
             if (!supportOptional) logger.warn('Sandbox version tooooooo low! Please upgrade to at least 1.2.0');
         }
         const body = { cmd: [proc({ execute, ...params })] };
         const id = callId++;
         if (argv.options.showSandbox) logger.debug('%d %s', id, JSON.stringify(body));
-        const res = await Axios.create({ baseURL: getConfig('sandbox_host') }).post('/run', body);
-        if (argv.options.showSandbox) logger.debug('%d %s', id, JSON.stringify(res.data));
-        [result] = res.data;
+        const res = await client.run(body);
+        if (argv.options.showSandbox) logger.debug('%d %s', id, JSON.stringify(res));
+        [result] = res;
     } catch (e) {
         if (e instanceof FormatError) throw e;
         // FIXME request body larger than maxBodyLength limit
diff --git a/packages/hydrojudge/src/sandbox/client.ts b/packages/hydrojudge/src/sandbox/client.ts
new file mode 100644
index 00000000..0bfc51bb
--- /dev/null
+++ b/packages/hydrojudge/src/sandbox/client.ts
@@ -0,0 +1,30 @@
+import axios, { AxiosInstance } from 'axios';
+import { SandboxRequest, SandboxResult, SandboxVersion } from './interface';
+
+export class SandboxClient {
+    private client: AxiosInstance;
+
+    constructor(baseURL: string) {
+        this.client = axios.create({ baseURL });
+    }
+
+    public run(req: SandboxRequest): Promise<SandboxResult[]> {
+        return this.client.post('/run', req).then((res) => res.data);
+    }
+
+    public getFile(fileId: string): Promise<Buffer> {
+        return this.client.get(`/file/${fileId}`).then((res) => res.data);
+    }
+
+    public deleteFile(fileId: string): Promise<never> {
+        return this.client.delete(`/file/${fileId}`);
+    }
+
+    public listFiles(): Promise<Record<string, string>> {
+        return this.client.get('/file').then((res) => res.data);
+    }
+
+    public version(): Promise<SandboxVersion> {
+        return this.client.get('/version').then((res) => res.data);
+    }
+}
diff --git a/packages/hydrojudge/src/sandbox/interface.ts b/packages/hydrojudge/src/sandbox/interface.ts
new file mode 100644
index 00000000..095ebb51
--- /dev/null
+++ b/packages/hydrojudge/src/sandbox/interface.ts
@@ -0,0 +1,143 @@
+export interface SandboxVersion {
+    buildVersion: string;
+    goVersion: string;
+    platform: string;
+    os: string;
+    copyOutOptional?: boolean;
+    pipeProxy?: boolean;
+}
+
+export interface LocalFile {
+    src: string;
+}
+
+export interface MemoryFile {
+    content: string | Buffer;
+}
+
+export interface PreparedFile {
+    fileId: string;
+}
+
+export interface Collector {
+    name: string;
+    max: number;
+    pipe?: boolean;
+}
+
+export type CopyInFile = LocalFile | MemoryFile | PreparedFile;
+export type CmdFile = LocalFile | MemoryFile | PreparedFile | Collector | null;
+
+/**
+ * Cmd defines a single command to be executed by sandbox server
+ */
+export interface Cmd {
+    args: string[];
+    env?: string[];
+    /** files defines open file descriptor for the command */
+    files?: CmdFile[];
+    tty?: boolean;
+
+    /** cpuLimit and clockLimit defines time limitations in ns */
+    cpuLimit?: number;
+    clockLimit?: number;
+    /** memoryLimit and stackLimit defines memory limitation in bytes */
+    memoryLimit?: number;
+    stackLimit?: number;
+    procLimit?: number;
+    /** cpuRateLimit defines cpu share limits in 1/1000 cpus if enabled in sandbox server */
+    cpuRateLimit?: number;
+    /** cpuSetLimit defines cpu set limit if enabled in sandbox server */
+    cpuSetLimit?: string;
+    /** strictMemoryLimit set rlimit_data limit for memoryLimit */
+    strictMemoryLimit?: boolean;
+
+    /** files to be copied into sandbox before execution */
+    copyIn?: Record<string, CopyInFile>;
+
+    /**
+     * files to be copied out from sandbox after execution.
+     * append '?' to make the file optional and do not cause FileError when missing
+     */
+    copyOut?: string[];
+    /** similar to copyOut but fileId returned instead */
+    copyOutCached?: string[];
+    /** copyOut limit in byte */
+    copyOutMax?: number;
+}
+
+/**
+ * SandboxRequest defines a single request to sandbox server
+ */
+export interface SandboxRequest {
+    requestId?: string;
+    cmd: Cmd[];
+    pipeMapping?: PipeMap[];
+}
+
+export enum SandboxStatus {
+    Accepted = 'Accepted',
+    MemoryLimitExceeded = 'Memory Limit Exceeded',
+    TimeLimitExceeded = 'Time Limit Exceeded',
+    OutputLimitExceeded = 'Output Limit Exceeded',
+    FileError = 'File Error',
+    NonzeroExitStatus = 'Nonzero Exit Status',
+    Signalled = 'Signalled',
+    InternalError = 'Internal Error',
+}
+
+export interface PipeIndex {
+    index: number;
+    fd: number;
+}
+
+export interface PipeMap {
+    in: PipeIndex;
+    out: PipeIndex;
+    /** enable pipe proxy */
+    proxy?: boolean;
+    /** if proxy enabled, save transmitted content */
+    name?: string;
+    max?: number;
+}
+
+export enum FileErrorType {
+    CopyInOpenFile = 'CopyInOpenFile',
+    CopyInCreateFile = 'CopyInCreateFile',
+    CopyInCopyContent = 'CopyInCopyContent',
+    CopyOutOpen = 'CopyOutOpen',
+    CopyOutNotRegularFile = 'CopyOutNotRegularFile',
+    CopyOutSizeExceeded = 'CopyOutSizeExceeded',
+    CopyOutCreateFile = 'CopyOutCreateFile',
+    CopyOutCopyContent = 'CopyOutCopyContent',
+    CollectSizeExceeded = 'CollectSizeExceeded',
+}
+
+export interface FileError {
+    name: string;
+    type: FileErrorType;
+    message?: string;
+}
+
+/**
+ * SandboxResult defines result from sandbox server
+ */
+export interface SandboxResult {
+    status: SandboxStatus;
+    /** contains error message if status is not Accept */
+    error?: string;
+    /** signal number if status is Signalled, otherwise exit status */
+    exitStatus: number;
+    /** cpu time in ns */
+    time: number;
+    /** peak memory in byte */
+    memory: number;
+    /** wall clock time in ns */
+    runTime: number;
+    /** copyOut file name to content (UTF-8 encoded and invalid character replaced) */
+    files?: Record<string, string>;
+    /** copyOutCached file name to fileId */
+    fileIds?: Record<string, string>;
+    /** contains detailed error if status is FileError */
+    fileError?: FileError[];
+}
diff --git a/packages/hydrojudge/src/sysinfo.ts b/packages/hydrojudge/src/sysinfo.ts
index 42699f77..90147e18 100644
--- a/packages/hydrojudge/src/sysinfo.ts
+++ b/packages/hydrojudge/src/sysinfo.ts
@@ -3,6 +3,7 @@ import fs from 'fs-extra';
 import { noop } from 'lodash';
 import { get as _get } from '@hydrooj/utils/lib/sysinfo';
 import { getConfig } from './config';
+import { Context } from './judge/interface';
 import { judge } from './judge/run';
 import * as tmpfs from './tmpfs';
 
@@ -11,7 +12,7 @@ export { update } from '@hydrooj/utils/lib/sysinfo';
 async function stackSize() {
     let output = '';
     try {
-        const context: any = {
+        const context: Context = {
             lang: 'cc',
             code: `#include <iostream>
 using namespace std;
@@ -33,8 +34,19 @@ int main(){
                 if (data.case) output = data.case.message;
             },
             end: () => { },
+            getLang: () => ({
+                compile: '/usr/bin/g++ -Wall -std=c++14 -o foo.cc foo.cc -lm',
+                execute: 'foo',
+                code_file: 'foo.cc',
+                highlight: 'cpp astyle-c',
+                monaco: 'cpp',
+                display: 'C++',
+                time_limit_rate: 1,
+                domain: [],
+                key: '',
+            }),
+            tmpdir: path.resolve(getConfig('tmp_dir'), 'sysinfo'),
         };
-        context.tmpdir = path.resolve(getConfig('tmp_dir'), 'sysinfo');
         fs.ensureDirSync(context.tmpdir);
         tmpfs.mount(context.tmpdir, '32m');
         await judge(context).catch((e) => console.error(e));
diff --git a/packages/hydrojudge/src/tmpfs.ts b/packages/hydrojudge/src/tmpfs.ts
index 5c05ea6a..4b732652 100644
--- a/packages/hydrojudge/src/tmpfs.ts
+++ b/packages/hydrojudge/src/tmpfs.ts
@@ -6,11 +6,15 @@ import log from './log';
 const linux = os.platform() === 'linux';
 if (!linux) log.warn('Not running on linux. tmpfs disabled.');
 
+const userInfo = os.userInfo();
+const uid = userInfo.uid;
+if (uid !== 0) log.warn('Not running by root. tmpfs disabled.');
+
 export function mount(path: string, size = '32m') {
     fs.ensureDirSync(path);
-    if (linux) child.execSync(`mount tmpfs ${path} -t tmpfs -o size=${size}`);
+    if (linux && uid === 0) child.execSync(`mount tmpfs ${path} -t tmpfs -o size=${size}`);
 }
 
 export function umount(path: string) {
-    if (linux) child.execSync(`umount ${path}`);
+    if (linux && uid === 0) child.execSync(`umount ${path}`);
 }
diff --git a/packages/hydrojudge/src/utils.ts b/packages/hydrojudge/src/utils.ts
index 53e1e0e5..f84378d4 100644
--- a/packages/hydrojudge/src/utils.ts
+++ b/packages/hydrojudge/src/utils.ts
@@ -16,7 +16,7 @@ export function parseFilename(filePath: string) {
     return t[t.length - 1];
 }
 
-const encrypt = (algorithm, content) => {
+const encrypt = (algorithm: string, content: crypto.BinaryLike) => {
     const hash = crypto.createHash(algorithm);
     hash.update(content);
     return hash.digest('hex');
@@ -56,7 +56,7 @@ export class Queue<T> extends EventEmitter {
 export namespace Lock {
     const data = {};
 
-    export async function aquire(key: string) {
+    export async function acquire(key: string) {
         // eslint-disable-next-line no-await-in-loop
         while (data[key]) await sleep(100);
         data[key] = true;