Browser tool
Image Converter & Resizer
Convert JPG, PNG, HEIC, and HEIF images to one or more WebP, AVIF, or JPEG XL sizes without uploading them.
Useful for: Preparing phone photos and transparent images for blogs, websites, and other web projects.
Built by frontend engineer Wataru Ito
Wataru’s Web Lab
Useful browser tools, playful web experiments, and practical frontend notes. I build things that solve real tasks, then write about how they work, what failed, and what I learned along the way.
Featured Tools
Focused tools you can use directly in your browser.
Browser tool
Background Remover & Image Cutout
Remove backgrounds from JPG, PNG, HEIC, WebP, AVIF, or JPEG XL images and export a transparent result.
Useful for: Creating product cutouts, profile images, stickers, and transparent assets for websites.
Browser tool
Image Upscaler
Enlarge JPEG, PNG, WebP, and AVIF images by 2× to 8× with Pica interpolation and light sharpening.
Useful for: Making small images larger without uploading them or generating imaginary detail with AI.
Browser tool
JSON, YAML, TOML & Query String Converter
Convert structured data between JSON, YAML, TOML, and nested Query Strings in either direction.
Useful for: Moving API payloads, configuration data, and search parameters between formats without uploading them.
Browser tool
Word Counter & Frequency Analyzer
Count words in real time, rank repeated terms, and highlight every exact occurrence in your draft.
Useful for: Reviewing repetition and word choice without uploading or saving the text.
Browser tool
Text to Image Generator
Turn multiline text into a polished square, portrait, or landscape image with local Canvas export.
Useful for: Creating social graphics for Twitter / X, Pinterest, Facebook, Instagram, and TikTok.
Browser tool
Emoji Copy & Paste
Search the complete Unicode Emoji 17.0 set by name, meaning, code point, or keyword.
Useful for: Adding the right emoji to merge requests, Slack, email, release notes, and documentation in seconds.
Browser tool
Micro Habit Development Sheet
Build a printable 22-day tracker for one small habit, with room for up to three daily actions.
Useful for: Making a tiny action visible and marking each day with checks, colors, or stickers.
Browser tool
Mandala Mind Map
A private, browser-based 9×9 canvas for goals, plans, and ideas.
Useful for: Expanding one central thought into eight themes and 64 practical actions or supporting ideas.
Games
Quick browser games with no signup required.
Word game
LEXAGON
Close word circuits from four sides to twelve by placing each missing letter in the glowing loop.
Good for: A tactile word puzzle where every completed edge powers the next side of a growing polygon.
Number game
Orbit
Rotate rings, align matching planets, and merge them to create 256 in a spatial 2048-style puzzle.
Good for: A tactile spatial-number puzzle: every turn reshapes the whole orbit, not just one tile.
Number game
Arithmix
Hunt through a luminous number grid and solve rapid-fire arithmetic prompts before time runs out.
Good for: A fast, tactile number hunt spanning mental arithmetic and prime numbers.
Number game
Number Crossword
Fill a sparse grid of crossing one-digit equations and make every line agree.
Good for: A relaxed arithmetic crossword where shared digits connect each equation.
Number game
Sort Break
Race through Bubble Sort one comparison at a time. Definitely not interview prep.
Good for: A tiny sorting brain break with guided comparisons.
Number game
Free Sort
Drag number cards into ascending order, or select any two cards to swap them.
Good for: A tactile sorting puzzle with free reordering and no prescribed algorithm.
Number game
Make 10
Trace neighboring numbers and combine them to hit the target before the 60-second timer runs out.
Good for: A quick arithmetic path puzzle with addition, subtraction, multiplication, and division.
Number game
Perfect Grid
Swap numbered tiles until every row, column, and diagonal reaches the same target sum.
Good for: A focused number puzzle with three grid sizes and no hints to give away the solution.
Word game
Daily Anagram
Unscramble ten familiar words and track completed numbered puzzles in your browser.
Good for: A quick word challenge with hundreds of selectable puzzle sets.
Word game
Anagram Solver
Enter 3–12 letters and find exact English anagrams, with common words shown first.
Good for: Checking a letter mix or exploring alternate arrangements.
Word game
Word Grid
Connect neighboring letters in a 4×4 grid and find as many familiar words as you can.
Good for: A relaxed word search with no timer and hundreds of selectable boards.
Word game
Sevenfold
Build a chain of words, follow the last letter, and loop through all seven letters back to the start.
Good for: A relaxed word chain with hundreds of selectable loops and no timer.
Creative
Creative coding, visual experiments, and interactive studies.
Interactive solar system
Orbital Garden
A three-dimensional solar system you can gently touch, distort, explore, and watch return to harmony.
Fluid study
Red Ink
Three drops of red ink slowly spread through a white vessel of water.
Coding study
AutoMata
A color-field study in which neighboring cells evolve together through flocking-like rules.
3D study variation
Kira Kira 3D
The color-flocking logic of AutoMata, expanded into a three-dimensional field of points.
Coding study variation
AutoMata: Red Field
A living field of red, crimson, magenta, and pink circles that breathe with their neighbors.
Study variation
Angle Field
A field of small lines turns with its neighbors while the background drifts through color.
Things I’d Rather Not Forget
Build notes, technical lessons, travel, parenting, and other things worth keeping.
Three Image Tools I Wanted for Myself
9/9/2026A birthday poster led to three small browser tools: remove a background, convert an image, and make it bigger. No account, and your image stays on your device.
Micro Habit Development Sheet: A Sticker Chart for Grown-Ups
9/8/2026A small printable habit sheet, inspired by the sticker charts that somehow work on kids—and sometimes on their parents too.
An Unexpected Path into Web Development
8/21/2026Why philosophy, art, and a builder's mindset have felt unexpectedly useful in my path into front-end development.
What Is the Best Primary Key?
5/11/2026Auto-increment IDs are fast and simple—but are they the best choice for a primary key? A practical breakdown of UUID v4, UUID v7, ULID, cuid2, Nano ID, and when each makes sense.
Is JavaScript pass-by-value or pass-by-reference?
3/25/2026A pragmatic explanation of how JavaScript handles values and references, with clear examples and mental models for understanding assignment and equality.
Other Notes
Occasional field notes from family travel and life between Japan and the United States.
In Japan? Get a Melon. A Whole One.
8/21/2026Tokyo has many luxuries, but few are as gloriously excessive—or as delicious—as a whole Sembikiya muskmelon.
Osaka with Kids: Universal Studios & More
3/20/2026A practical guide for families traveling to Osaka with children, featuring Universal Studios Japan, Kids Plaza, and Hug Museum. Tips for planning, access, and making the most of your visit.
Eat Japan with Kids
3/18/2026A practical guide to family-friendly dining in Japan, highlighting affordable and tasty chain restaurants that are welcoming to children.