Client-side · files never leave your browser
Pure client-side tools for devs, designers, and everyone
PDF merge/split/compress, HEIC → JPG, image-to-PDF, color converter, JWT, regex, JSON, mock API, Taiwan test data… all running in your browser. Files never upload.
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Reference
Percentile calculator
Paste response times → p50/p90/p95/p99 + Apdex
Developer & API
JWT decoder / generator
Decode header / payload / expiry, re-sign with secret
Developer & API
cURL ↔ fetch ↔ Python converter
Paste a cURL command → emit fetch / Python requests / HTTPie
Developer & API
CSS / XPath selector tester
Paste HTML + selector → live highlight of matches
Developer & API
Regex builder & live tester
Pattern + sample text → live highlight + capture groups
Developer & API
Mock API designer
Design endpoints → export Mockoon / Playwright / Postman / json-server config
Developer & API
Hash Tools (MD5 / SHA-1/256/384/512)
Live text hashing + file integrity checks — 5 algorithms side-by-side. WebCrypto + hand-rolled MD5, pure frontend
Developer & API
UUID Generator (v4 / v7 batch)
Generate 1-1000 UUIDs (random v4 or time-ordered v7) at once; tunable case / hyphens / braces. Backend & test data must-have
Developer & API
Regex Replace + Group Preview
Three-pane live editor: pattern / replacement / input; preview captures ($1, $2) and named groups ($<name>); all 6 flags toggleable
Developer & API
Cron Expression Visualiser
5-field breakdown + natural-language description + next-N firings. Supports @daily aliases, month / dow names, step and range
Developer & API
Password Strength + Crack Time
Pure-frontend entropy estimate + 5 attacker profiles (rate-limited online → GPU offline). Weak-pattern detection; passwords never leave the browser
Developer & API
AI Token Counter (GPT / Claude / Gemini)
Estimate tokens + cost + context-window fit across 5 leading AI models. Heuristic (no 1MB WASM), ±10% accurate for typical prose
Developer & API
JSON → TypeScript
Infer TypeScript types from any JSON live: name nested types, merge shapes across array elements, mark optional fields, support readonly
Data / Format / Text
Taiwan test data generator
Valid TW national ID, BAN, mobile, Luhn credit cards
Data / Format / Text
JSON formatter + Schema validator
Format / minify / sort + JSON Schema validation
Data / Format / Text
Unix time & timezone converter
Seconds / ms / ISO interop with timezone-aware display
Data / Format / Text
Markdown batch translator
Bring-your-own OpenAI / Anthropic / Google API key. Batch-translate .md files while preserving frontmatter / code / links
Data / Format / Text
QR Code generator (with Logo)
URL / WiFi / vCard / Email payloads, custom colours, centre logo, PNG / SVG output. Free, no watermark
Data / Format / Text
Code Beautifier / Minifier (10 languages)
Prettier-backed formatter for JS / TS / CSS / HTML / JSON / Markdown / YAML, plus one-click minify for JSON / CSS / HTML. Auto-detects language
Data / Format / Text
Markdown Editor (live preview)
Side-by-side live preview with GFM tables / task lists / code blocks; export to HTML snippet or styled standalone HTML file
Data / Format / Text
URL / Base64 / HTML encoder
Six formats, two-way conversion — URL, URI component, Base64, Base64URL, HTML entities, Unicode escape. Backend / scraping / debugging swiss-army
Data / Format / Text
JSON deep diff (visual)
Side-by-side deep diff of two JSON docs with path-based highlight (added / removed / changed), array by-index comparison. Backend / API / config diff power tool
Data / Format / Text
CSV / TSV viewer + converter
RFC 4180 parser, tabular preview with per-column stats (unique / empty / numeric), one-click export to JSON / TSV / Markdown / CSV
Data / Format / Text
Lorem Ipsum (Latin / Chinese / Tech)
Three banks: classic Lorem Ipsum, Traditional Chinese filler (for CJK mockups), and product-tech vocabulary. Output by words / sentences / paragraphs; seedable
Data / Format / Text
Unix Timestamp ↔ Timezones
Paste epoch (s / ms) or ISO; see live conversion across multiple timezones plus a relative-time description. Backend log debug must-have
Data / Format / Text
Text Diff (line-by-line)
Plain-text LCS line diff with side-by-side view, colour-coded added / removed / changed, ignore-whitespace / case toggles, unified diff export
Data / Format / Text
Case Converter
Convert between camelCase / PascalCase / snake_case / kebab-case / CONSTANT_CASE / Title / Sentence / dot / path — 9 forms at once
Data / Format / Text
Slugify (URL-friendly, CJK-aware)
Turn any title into a URL slug: strip accents, collapse punctuation, normalise case. CJK characters preserved by default (or drop them)
Data / Format / Text
Emoji Info Lookup
250+ curated emoji with category filter; click for codepoint / shortcode / HTML entity. Paste an emoji to reverse-lookup
Visual / CSS
cubic-bezier editor
Visual CSS easing curve editor — drag two control points, output CSS / Tailwind v4 / Framer Motion / @keyframes
Visual / CSS
CSS gradient editor
Linear / radial / conic gradient editor — live preview, output CSS / Tailwind v4 arbitrary class / SVG
Visual / CSS
Type scale + Fluid clamp() generator
Modular ratio + dual-viewport clamp() to compute a full type scale. Outputs Tailwind v4 @theme / CSS vars / SCSS
Visual / CSS
box-shadow editor (multi-layer + Material elevation)
Visual multi-layer CSS shadow editor with Tailwind 5-level + Material Design 9-elevation presets
Visual / CSS
Glassmorphism + Neumorphism generator
Glass (backdrop-filter) + Neumorphism (paired light/dark shadows for raised/inset) — both in one tool, with 3 preview backgrounds
Visual / CSS
CSS clip-path editor
Drag points to build polygon / circle / ellipse / inset shapes; 9 presets (triangle / hexagon / star / arrow…); export CSS / Tailwind v4 / SVG path
Visual / CSS
Mermaid Diagram Editor
Write flowcharts / sequence / gantt / mindmap / class / pie diagrams in plain text with live preview; download as SVG or PNG
Visual / CSS
CSS Grid Generator
Edit rows / cols / gap / named areas; live preview + one-click CSS export. Includes Holy Grail, Dashboard 12-col presets
Color / Accessibility
Color format converter
Live two-way conversion between hex / rgb / hsl / oklch / oklab + nearest Tailwind class
Color / Accessibility
Tailwind palette generator
Generate the full 50-950 shade ramp from one brand colour. Outputs Tailwind v4 @theme, v3 config, and CSS variables
Color / Accessibility
WCAG + APCA contrast checker
Live WCAG 2.1 ratio + APCA Lc for any foreground/background pair, with one-click fix suggestion when failing
Color / Accessibility
Colour-blindness Simulator (8 + normal)
Brettel / Machado matrix simulation of 8 deficiencies. Compare palettes or your own image side-by-side. Designer-grade accessibility check
Image / PDF / Media
Image ↔ Base64
Drop images → data URI / raw base64 / HTML / CSS one-click copy; paste base64 → preview + download
Image / PDF / Media
HEIC → JPG / PNG / WebP
Convert iPhone .heic photos to common formats, batch processing + ZIP download, all in your browser
Image / PDF / Media
Image compress to size
Binary-search JPEG quality to hit a target file size (300KB / 500KB / 2MB / etc.) — for job sites, government forms, upload limits
Image / PDF / Media
Image Crop (free / aspect / circular)
Visual drag-to-crop with locked aspect ratios (1:1 / 16:9 / 3:2…), circular mask for avatars, export PNG / JPG / WebP with custom output width
Image / PDF / Media
Image Resize (fit / longest-edge / scale)
Four modes: fit-inside box, cap longest edge, percentage scale, force exact size. Outputs JPG / PNG / WebP, never enlarges by default
Image / PDF / Media
Favicon all-in-one generator
Three input modes (emoji / text / upload) → favicon.ico, every PNG size, PWA maskable, HTML snippet, manifest, packaged ZIP
Image / PDF / Media
SVG Optimizer
Pure-frontend SVG slimmer: strip comments / metadata / editor attributes / default values / empty groups, round decimals; side-by-side preview + savings %
Image / PDF / Media
Image → PDF
Drag-sort multiple images into one PDF — paper size / orientation / N-up / margin / quality, pure client-side
Image / PDF / Media
PDF merge / split / extract
Combine multiple PDFs, split into multiple files by range (ZIP), or extract selected pages — pure client-side
Image / PDF / Media
PDF compress
Two modes — lossless light (keeps text) or rasterize heavy (50-80% smaller, text becomes images)
Image / PDF / Media
PDF page editor
Thumbnail grid — select, rotate, delete, duplicate, reorder pages, then export. Pure client-side
Image / PDF / Media
PDF unlock / remove password
Strip print / copy restrictions (no password needed), or decrypt an encrypted PDF with the password you already know
Image / PDF / Media
PDF watermark + page numbers
Text or image watermark with diagonal tiling, opacity & rotation; auto page numbers. Pure front-end — files never leave the browser
Image / PDF / Media
PDF → Images (PNG / JPG / WebP)
Render each PDF page as a high-resolution image; pick page range + scale, multi-page output zipped. Pure frontend, ideal for contracts / reports / confidential docs
Image / PDF / Media
Images → GIF Animation
Combine multiple images into a GIF; drag to reorder, tune delay / loop / size / palette colours. Pure-frontend gifenc encoder, no upload
Image / PDF / Media
Video → GIF
Drop an MP4 / WebM / MOV; pick a time window and fps; in-browser seek + canvas + gifenc emit a GIF. No upload
Reference
Test framework cheatsheet
Robot Framework / Playwright / Appium quick reference
Reference
HTTP Status Codes
60+ HTTP status codes in one place. Filter by class, search by digits or keywords; RFC refs + common-misuse notes (401 vs 403, 302 vs 307)
Reference
npm Bundle Size Lookup
Look up minified / gzip size, dependency count, tree-shakeability. Compare multiple packages side-by-side for dep decisions