All the web tools you need, completely free.
Word counters, password generators, QR code creators and more —
free tools to make everyday tasks easier.
Why Yuustudio?
Local Processing First
Text and image workflows avoid uploads and run in the browser when practical. Network use such as IP lookup or AI model downloads is identified clearly.
Free & No Sign-up
No account or installation is required. Supported formats, capacity, and accuracy limits are documented inside each tool.
Japanese & English
Full UI and documentation in both Japanese and English. Switch languages anytime using the toggle in the header.
Tools
AI Background Remover
Remove image backgrounds locally with AI, then refine edges with brush and lasso controls.
AI Denoiser & Upscaler
Load Real-ESRGAN only when needed and run local denoise plus 1×/2×/4× PNG output.
Image Optimizer Studio
Convert JPEG/PNG/WebP with exact dimensions, quality control, size comparison, and verified browser format support.
QR Code Generator & Reader
Create and decode-validate URL, text, and Wi-Fi QR codes, scan via camera/image, and export PNG or SVG.
Timer, Stopwatch & Counter
A preset countdown, lap stopwatch, and persistent counter with configurable goal progress.
Word Counter
Count characters, words, and lines in real time. Perfect for articles and reports.
Password Generator
Generate 8–128 characters with cryptographic randomness, required classes, ambiguous-character removal, and strength checks.
Images to PDF
Reorder and rotate up to 100 images, then set A4/Letter paper, margins, fit, DPI, and PDF quality.
JSON Formatter
Format, minify, and sort JSON with error context, structure statistics, and file download.
Unit Converter
Convert units across 10 categories with adjustable precision and an all-unit comparison table.
Base64 Converter
Convert text and files with Base64 or Base64URL, including Data URLs and binary reconstruction.
IP Address Checker
Check your public IP, IPv4/IPv6 version, connection country, browser, and device details on demand.
Hash Generator
Hash text or files up to 256 MiB with SHA-1/256/384/512 and verify expected checksums.
YAML ⇄ JSON Converter
Bidirectional conversion with multiple YAML documents, schema choice, error locations, sorting, and indent control.
CSV ⇄ JSON Converter
Accurate CSV/JSON conversion with quoted newlines, type inference, width warnings, preview, and BOM.
Markdown to HTML
Sanitized GFM preview with heading outline, document statistics, and complete HTML export.
Regex Tester
Run regex in a time-limited worker with captures, replacement, positions, and TSV/JSON export.
Image & PDF OCR
Extract text from images and the first 24 PDF pages with languages, quality modes, progress, cancel, and TXT export.
JSON Schema Validator (schema validation)
High-performance Ajv schema validation with timing metrics and structured error output.
Case Converter (text casing)
Convert text into 11 prose and programming case formats with individual copy controls.
Text Diff (line comparison)
Compare by line or word, ignore case/whitespace, inspect stats, and copy or save a unified diff.
Slug Generator (SEO URL slug)
Batch-create unique URL slugs with Unicode, stop-word, length, and encoded-path controls.
UUID Generator (unique IDs)
Generate up to 1,000 RFC 4122 UUID v4 values with cryptographic randomness, formatting, validation, and export.
URL Encoder (encode/decode)
Convert components, complete URLs, and form values, then inspect query parameters and URL structure.
JWT Decoder (token inspection)
Inspect JWT header, payload, time claims, and expiry locally with a clear unverified-signature warning.
Cron Parser (schedule preview)
Validate five-field Unix cron and preview 20 runs in a selected timezone with a readable summary.
Timezone Converter (time shift)
Convert across IANA timezones with DST-aware logic and detect ambiguous or nonexistent local times.
Image Crop + Rotate
Free/fixed crop, rotate, flip, zoom, downscale, and export to PNG, JPEG, or WebP.
Guides & Articles
About Yuustudio
Yuustudio is a free web tool portal developed and maintained by a university student majoring in Information Engineering. It offers 28+ tools including word counters, password generators, QR code creators, JSON formatters, image compressors, AI background removers, and more — all designed to streamline everyday tasks.
Text and image conversions prioritize local processing without uploading input files. Features that require communication, such as IP lookup or AI model downloads, are identified before use. Automated tests cover core conversion logic, while supported formats and limits are kept aligned between implementation and documentation.
Japanese and English interfaces and documentation are provided, and bug reports are accepted through the contact page. Existing tools are improved before adding more, and features that cannot be maintained to a useful standard are retired.