Productivity & Utilities
Browser-native utility tools that execute 100% locally on your computer. No user accounts, registration, or server-side communication.
Pomodoro Timer
This is a productivity tool that alternates between 25 minutes of concentration time and 5 minutes of break time, and notifies you with a sound or desktop notification when the work is completed.
Random Picker
The entered name list will be shuffled, randomly divided into teams, and representatives will be selected using a roulette wheel.
Speech to Text
The audio obtained from the microphone is transcribed in real time and output as text that can be edited and copied.
Flashcard App
Create an original vocabulary book and perform memorization efficiently based on the timing of the forgetting curve (spaced repetition).
Metronome
This is a rhythm/performance tool that plays a click sound at a precise tempo according to the specified BPM and time signature, and makes the screen blink.
Breathing Timer
This is a breathing method guidance tool that helps you meditate and relieve stress by following an animation that tells you when to breathe (inhale, hold, exhale).
Typing Test
Test your character input speed (WPM) and accuracy by accurately typing short English or Japanese Romaji texts within a time limit.
Noise Meter
The surrounding volume (sound pressure level) from the microphone is collected in real time, and the simple decibel (dB) value of the entire environment is displayed on a meter.
Screen Tester
Displays the entire screen in a single color (red, green, blue, white, black, etc.) and inspects the LCD monitor for missing dots, color unevenness, and light leakage.
Random Generator
Performs dice rolling, coin tossing, and generation of a random number list within a specified range with intuitive 3D-like animation.
Piano Synth
A piano keyboard that runs on your browser. You can enjoy simple performances by selecting a sound wave waveform and assigning keys on your mouse or PC keyboard.
Math Drill Generator
Randomly generate quizzes on addition, subtraction, multiplication, and division. It is optimized for print layout (A4), and you can also toggle display/hide of answers.
Habit Tracker
Enter the daily goals you want to make into a habit (exercise, study, etc.), check the calendar on the day you achieve them, and display a list of your continuation rates.
World Clock
Display the current time in major world cities side by side in analog and digital format, and use the slider to compare time differences (meeting candidate times, etc.).
BMI Calculator
Based on height, weight, age, and activity intensity, obesity degree (BMI), basal metabolism (BMR), and total calorie expenditure (TDEE) are calculated and drawn on a visual meter.
Pixel Art Editor
You can create pixel art on a 16x16 or 32x32 grid, set layers and animation frames, and save it as a transparent PNG or GIF animation.
Maze Generator
You can play the game by generating a random maze using an algorithm and manually aiming for the goal, or you can watch the automatic solving process of the search algorithm through animation.
Virtual Art Gallery
While viewing public domain Western masterpieces in high quality, you can customize the frame style and exhibition room lighting, and extract the colors (HEX code) of each work.
Generative Art Math
You can create and save beautiful geometric art in real time by adjusting mathematical models such as fractals, chaotic orbits, and golden angle Fibonacci spirals.
Noise Generator Healing
This is a concentration BGM synthesis tool that allows you to blend white noise, pink noise, brown noise, and the sounds of rain, wind, and waves to your desired balance.
Stopwatch Lap
This is a tool that can measure lap times and split times infinitely in 1/1000 second units, graph average laps, highest/lowest laps, and export them as CSV files.
Periodic Table Interactive
This is an educational illustrated book that visually displays detailed physical properties, electronic configuration (bohr model animation display), absorption and emission spectra, etc. by clicking on each element in the periodic table of elements.
Flight Timezone Planner
When you enter the time difference and flight time, it creates a timeline of how local time progresses during the flight, and graphically calculates your sleep and activity plan to prevent jet lag.
Rubiks Cube 3d
This is a 3D Rubik's Cube that uses CSS 3D Transforms and can be moved intuitively by dragging.
Reversi Ai
This is an Othello tool that allows you to play against a mini AI using Monte Carlo tree search and evaluation functions, and analyze the winning rate of each square in a heat map in real time.
Sudoku Solver
This is a tool that allows you to play Sudoku puzzles of different difficulty levels, or automatically answers input puzzles using a backtracking algorithm, and visualizes the search process with animation.
Sound Recorder Sampler
This is a portable sampler that allows you to record environmental sounds and voices from a microphone, and then assign them to a keyboard or drum pad to enjoy sampled performances.
Kanban Board
A secure Kanban board task management tool that saves in LocalStorage, allowing you to move cards intuitively using drag and drop.
Ear Age Test
This is a tool that uses the Web Audio API to generate high-frequency sounds from 8kHz to 20kHz to easily measure and test ear age based on the hearing limit.
Simon Says Game
This is a classic brain training game (Simon) in which you memorize the pattern order of panels with lights and sounds, and correctly reproduce sequences that gradually become longer.
Conway Game Of Life
This is a tool that allows you to simulate Conway's Game of Life on your browser and observe the dynamic changes of cell birth and death.
Slide Puzzle 15
This is a tool that allows you to play the classic 15 puzzles, or create a split puzzle from your own images, and enjoy the automatic shortest strategy animation using the A* algorithm.
Mindmap Creator
It is a mind map editor that allows you to easily add nodes with key operations, organize the layout intuitively, and export it as SVG or PNG.
Digital Bookshelf
This is a completely local digital bookshelf where you can take pictures of the covers of the manga and novels you have purchased, register them, and manage your collection by arranging them in order of volume number.
Secure Client-Side Sandbox
All tools displayed in this category run locally in your browser sandbox. None of the inputs, file data, or processing logs are sent to any remote servers or APIs.
Productivity & Utilities: Comprehensive Guide
Pomodoro timers, habit tracking, unit converters, and offline PWA tools
From focus-boosting Pomodoro timers and personal habit trackers to unit converters, QR code generators, and mind maps, ZeroTools provides a distraction-free suite of daily productivity tools. Every utility supports offline PWA installation, ensuring seamless workflow continuity anywhere.
Offline-First PWA Architecture
Install directly to your home screen or desktop and use all tools without an active internet connection.
Private Data Persistence
Your daily notes and habit tracking metrics remain strictly on your physical device.
Fast, Lightweight & Responsive
Zero background bloat ensures instant tool startup and smooth performance on mobile and desktop.
1IndexedDB Local Storage for Private Habit & Task Management
Track habits, manage Kanban boards, and organize reading lists with data persisted securely in your browser's IndexedDB. Your productivity logs remain on your device with no mandatory account creation.
2Distraction-Free Focus & Daily Utility Workflow
Leverage scientific 25-minute Pomodoro cycles, breathing timers, white noise generators, and quick calculation tools with clean, ad-free, and popup-free interfaces.